Achieving Sustainable Production of Milk Volume 3: Dairy Herd Management and Welfare 1786760525, 9781786760524

Table of contents :
Contents
Series list
Preface
References
Introduction
Part 1 Welfare of dairy cattle
Part 2 Nutrition of dairy cattle
Part 3 Health of dairy cattle
Part 1 Welfare of dairy cattle
Chapter 01 Understanding the behaviour of dairy cattle
1 Introduction
2 Studying the preferences of cattle: an overview
3 Cattle perception
4 Social, nutritional and reproductive behaviour
5 Locomotion and resting
6 Behaviour during transport and slaughter
7 Conclusions
8 Future trends
9 Where to look for further information
10 References
Chapter 02 Key issues in the welfare of dairy cattle
1 Introduction: an overview of interest in and determinants of animal welfare in dairy farming
2 Husbandry practices in dairy farming: housing, handling and farming procedures
3 Husbandry practices in dairy farming: health, productivity and breeding
4 Applying different perspectives on animal welfare to the case of dairy farming
5 Recommendations for improving animal welfare in dairy farming in the light of expected future developments
6 Summary
7 Where to look for further information
8 Acknowledgements
9 References
Chapter 03 Housing and the welfare of dairy cattle
1 Introduction
2 Types of housing system
3 Stall design
4 Flooring and locomotion
5 Social competition, social dominance and overstocking
6 Group versus individual housing for un-weaned calves: effects on health, locomotion and rest
7 Group versus individual housing for un-weaned calves: behaviour and weight gain
8 Reflections on housing un-weaned calves individually, in groups and with cows
9 Conclusions
10 Where to look for further information
11 References
Chapter 04 Genetic selection for dairy cow welfare and resilience to climate change
1 Introduction
2 Selection indices
3 Selection for milk production, energy balance and fertility
4 New breeding objectives: health traits
5 New breeding objectives: dairy cows and climate change
6 Genomic selection, inbreeding and gene editing
7 Summary
8 Where to look for further information
9 Acknowledgements
10 References
Chapter 05 Ensuring the welfare of culled dairy cows during transport and slaughter
1 Introduction
2 Legislation and codes of practice
3 Pre-transport conditions that influence the welfareof cows during transport
4 Welfare of culled cows during transport
5 The effects of livestock markets on cow welfare
6 Welfare of cows at the slaughter plant
7 Conclusions
8 Where to look for further information
9 References
Chapter 06 Ensuring the health and welfare of dairy calves and heifers
1 Introduction
2 Newborn calf vitality
3 Colostrum management
4 Health management
5 Housing considerations
6 Feeding management
7 Managing weaned calves
8 Summary
9 Where to look for further information
10 References
Part 2 Nutrition of dairy cattle
Chapter 07 The rumen microbiota and its role in dairy cow production and health
1 Introduction
2 Diversity and function of rumen microbiota
3 Factors influencing composition of rumen microbiota
4 Current trends and innovations in studying the rumen microbiome: ‘omics’ approaches
5 Current trends and innovations in studying the rumen microbiota: linkage with host phenotypes
6 Altering rumen function by manipulating microbiota
7 Knowledge gaps and future directions
8 Conclusions
9 Where to look for further information
10 References
Chapter 08 Biochemical and physiological determinants of feed efficiency in dairy cattle
1 Introduction
2 The physiological and biochemical makeup of a dairy animal
3 Development of the research field: a brief overview
4 A case study on the biochemical determinants of feed efficiency
5 Mechanisms and effects of simple genetic variation
6 Summary and conclusions
7 Future trends in research
8 Where to look for further information
9 References
Chapter 09 Feed evaluation and formulation to maximise nutritional efficiency in dairy cattle
1 Introduction
2 Evaluation of feed energy value
3 Alternative methods to predict digestibility and energy value
4 Discounts of digestibility and associative effects
5 Conversion of digestible nutrients to metabolisable energy and net energy concentration
6 Evaluation of feed protein value
7 Estimation of microbial protein
8 Determination of rumen undegraded protein (RUP)
9 Evaluation of feed protein systems
10 Summary and future perspectives
11 Where to look for further information
12 References
Chapter 10 Sustainable nutrition management of dairy cattle in intensive systems
1 Introduction
2 Phosphorus issues 
3 Nitrogen issues
4 Carbon: a case study of enteric methane emissions and nutritional management in the intensive dairy production systems of California and Wisconsin
5 Conclusions
6 References
Chapter 11 Nutrition management of grazing dairy cows in temperate environments
1 Introduction
2 Economic factors affecting grazing system design
3 Using supplementary feed to manage pasture
4 Nutrition of grazing dairy cows: pasture as a feed
5 Choosing the right supplementary feed
6 Choosing the right genetics for a grazing system
7 Supplement effects on milk production
8 Practical nutrition management on the farm
9 Conclusions and implications
10 Where to look for further information
11 References
Chapter 12 The use and abuse of cereals, legumes and crop residues in rations for dairy cattle
1 Introduction
2 Current and future levels of animal sourced food (ASF) production
3 Dairy ration compositions and current and projected feed demand and supply
4 Context specificity of feed demand and supply
5 Ration composition and ceilings to milk productivity
6 Optimizing the feed–animal interface: ration balancing in intensive and extensive dairy systems
7 Summary
8 Where to look for further information
9 References
Chapter 13 Feed supplements for dairy cattle
1 Introduction
2 Dietary buffers to control rumen acidity
3 Antibiotics for improved production
4 Fat supplementation
5 Immunological control of the rumen microbial population
6 Plant extracts to manipulate rumen fermentation, boost production and decrease emissions
7 Direct-fed microbials, probiotics and exogenous fibrolytic enzymes
8 Other supplements to control GHG emissions
9 Conclusion
10 Where to look for further information
11 References
Part 3 Health of dairy cattle
Chapter 14 Disorder of digestion and metabolism in dairy cattle: the case of subacute rumen acidosis
1 Introduction
2 Prevalence, aetiology and biological consequences of ruminal acidosis
3 Regulation of ruminal pH
4 The dogma of ruminal acidosis
5 Case study: SARA risk in the post-partum phase of the transition period
6 Other examples of SARA risk induced by low feed intake
7 Conclusion and future trends
8 Where to look for further information
9 References
Chapter 15 Management of dairy cows in transition and at calving
1 Introduction
2 Problems with using disease events to monitor herd transition management
3 Alternative data sources for monitoring herd transition management
4 Introduction to management factors that influence transition outcomes
5 Cow-level factors
6 Housing and environmental factors
7 Factors related to the decisions and actions of human caretakers
8 Case study: use of the transition cow risk assessment instrument 
9 Summary and future trends
10 Where to look for further information
11 References
Chapter 16 Causes, prevention and management of infertility in dairy cows
1 Introduction
2 Bovine parturition and uterine health
3 Bovine post-partum metabolic environment and ovarian activity
4 Oestrus in dairy cows
5 Establishing pregnancy in dairy cows
6 Heat stress and bovine fertility
7 Heifer fertility
8 Genetics and bovine fertility
9 Future trends and conclusion
10 Where to look for further information
11 References
Chapter 17 Aetiology, diagnosis and control of mastitis in dairy herds
1 Introduction
2 Indicators of mastitis: somatic cell count
3 Indicators of mastitis: non-cell inflammation markers
4 Contagious pathogens causing mastitis
5 Environmental pathogens: Escherichia coli, Klebsiella and environmental streptococci
6 Other pathogens: Prototheca, coagulase-negative staphylococci and other microorganisms
7 Management and control of mastitis
8 Dry cow therapy
9 The use of antibiotics
10 Where to look for further information
11 References
Chapter 18 Preventing and managing lameness in dairy cows
1 Introduction
2 Lameness in dairy cows: associated pain, prevalence and incidence
3 Recording causes and ensuring prompt and effective treatment
4 Lesion aetiology and categories of risk for the four main causes of lameness in dairy cows
5 Risk assessments and cost-effective interventions
6 Conclusions: how assessment, evaluation and facilitation is driving improvement
7 Where to look for further information
8 References
Chapter 19 Control of infectious diseases in dairy cattle
1 Introduction
2 The impact of infectious diseases
3 Principles of risk analysis and management
4 Hazard and risk identification
5 Risk assessment and evaluation
6 Risk management
7 Risk communication
8 Ensuring effective implementation
9 Trends in infectious disease control strategies
10 Conclusion
11 Where to look for further information
12 Abbreviations
13 References
Chapter 20 Prevention and control of parasitic helminths in dairy cattle: key issues and challenges
1 Introduction
2 Helminth threats to grazing dairy cattle
3 Anthelmintic resistance
4 Progress in the development of evidence-based control programmes to reduce selection pressure for anthelmintic resistance
5 The development of robust diagnostics to support evidence-based control
6 Vaccine development
7 Future trends in research: contributions to enhanced and sustainable production
8 Concluding remarks
9 Where to look for further information
10 References
Chapter 21 Genetic variation in immunity and disease resistance in dairy cows and other livestock
1 Introduction
2 Genetic variation in resistance to disease
3 The sources of genetic variation in resistance to disease
4 Strategies for breeding to increase resistance to disease
5 Case study 1: resistance to cattle tick infestation
6 Case study 2: mastitis in cattle
7 Case study 3: bovine respiratory disease (BRD) complex
8 Case study 4: additive and non-additive genetic variation
9 Conclusions
10 Where to look for further information
11 References
Chapter 22 Responsible and sustainable use of medicines in dairy herd health
1 Introduction
2 Antimicrobial resistance
3 Inappropriate behaviours and practices
4 Making progress towards change
5 Delivering results
6 Future trends and conclusion
7 Where to look for further information
8 Acknowledgements
9 References
Chapter 23 Dairy herd health management: an overview
1 Introduction
2 The development of dairy herd health management (HHM)
3 Motivation for implementing HHM
4 Measuring: data for HHM
5 Monitoring: approaches to monitoring in HHM
6 Managing: delivering progress in HHM through planning, training and support for schemes
7 The potential benefits of HHM
8 Conclusions
9 Where to look for further information
10 References
Index

Citation preview

http://dx.doi.org/10.0000/00000.0000 © Burleigh Dodds Science Publishing Limited, 2016. All rights reserved.

Achieving sustainable production of milk Volume 3: Dairy herd management and welfare

It is widely recognised that agriculture is a significant contributor to global warming and climate change. Agriculture needs to reduce its environmental impact and adapt to current climate change whilst still feeding a growing population, i.e. become more ‘climate-smart’. Burleigh Dodds Science Publishing is playing its part in achieving this by bringing together key research on making the production of the world’s most important crops and livestock products more sustainable. Based on extensive research, our publications specifically target the challenge of climate-smart agriculture. In this way we are using ‘smart publishing’ to help achieve climate-smart agriculture. Burleigh Dodds Science Publishing is an independent and innovative publisher delivering high quality customer-focused agricultural science content in both print and online formats for the academic and research communities. Our aim is to build a foundation of knowledge on which researchers can build to meet the challenge of climate-smart agriculture. For more information about Burleigh Dodds Science Publishing simply call us on +44 (0) 1223 839365, email [email protected] or alternatively please visit our website at www.bdspublishing.com.

Related titles: Achieving sustainable production of milk Volume 1: Milk composition, genetics and breeding Print (ISBN 978-1-78676-044-9); Online (ISBN 978-1-78676-046-3, 978-1-78676-047-0) Achieving sustainable production of milk Volume 2: Safety, quality and sustainability Print (ISBN 978-1-78676-048-7); Online (ISBN 978-1-78676-050-0, 978-1-78676-051-7) Ensuring safety and quality in the production of beef Volume 1: Safety Print (ISBN 978-1-78676-056-2); Online (ISBN 978-1-78676-058-6, 978-1-78676-059-3) Ensuring safety and quality in the production of beef Volume 2: Quality Print (ISBN 978-1-78676-060-9); Online (ISBN 978-1-78676-062-3, 978-1-78676-063-0) Chapters are available individually from our online bookshop: https://shop.bdspublishing.com

BURLEIGH DODDS SERIES IN AGRICULTURAL SCIENCE NUMBER 10

Achieving sustainable production of milk Volume 3: Dairy herd management and welfare Edited by Emeritus Professor John Webster, University of Bristol, UK

Published by Burleigh Dodds Science Publishing Limited 82 High Street, Sawston, Cambridge CB22 3HJ, UK www.bdspublishing.com Burleigh Dodds Science Publishing, 1518 Walnut Street, Suite 900, Philadelphia, PA 19102-3406, USA First published 2017 by Burleigh Dodds Science Publishing Limited © Burleigh Dodds Science Publishing, 2017. All rights reserved. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission and sources are indicated. Reasonable efforts have been made to publish reliable data and information but the authors and the publisher cannot assume responsibility for the validity of all materials. Neither the authors not the publisher, nor anyone else associated with this publication shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher. The consent of Burleigh Dodds Science Publishing Limited does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from Burleigh Dodds Science Publishing Limited for such copying. Permissions may be sought directly from Burleigh Dodds Science Publishing at the above address. Alternatively, please email: [email protected] or telephone (+44) (0) 1223 839365. Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identification and explanation, without intent to infringe. Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of product liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Library of Congress Control Number: 2016962692 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 978-1-78676-052-4 (print) ISBN 978-1-78676-054-8 (online) ISBN 978-1-78676-055-5 (online) ISSN 2059-6936 (print) ISSN 2059-6944 (online) Typeset by Deanta Global Publishing Services, Chennai, India Printed by Lightning Source

Contents Series list

xii

Preface

xvi

Introduction xx Part 1  Welfare of dairy cattle 1 Understanding the behaviour of dairy cattle 3 C. J. C. Phillips, University of Queensland, Australia 1 Introduction 3 2 Studying the preferences of cattle: an overview 5 3 Cattle perception 6 4 Social, nutritional and reproductive behaviour 7 5 Locomotion and resting 11 6 Behaviour during transport and slaughter 13 7 Conclusions 14 8 Future trends 14 9 Where to look for further information 15 10 References 17 2 Key issues in the welfare of dairy cattle 21 Jan Hultgren, Swedish University of Agricultural Sciences, Sweden 1 Introduction: an overview of interest in and determinants of animal welfare in dairy farming 21 2 Husbandry practices in dairy farming: housing, handling and farming procedures 25 3 Husbandry practices in dairy farming: health, productivity and breeding 31 4 Applying different perspectives on animal welfare to the case of dairy farming 34 5 Recommendations for improving animal welfare in dairy farming in the light of expected future developments 38 6 Summary 41 7 Where to look for further information 41 8 Acknowledgements 42 9 References 43 3 Housing and the welfare of dairy cattle 53 Jeffrey Rushen, University of British Columbia, Canada 1 Introduction 53 2 Types of housing system 54 3 Stall design 57 4 Flooring and locomotion 62 5 Social competition, social dominance and overstocking 64 6 Group versus individual housing for un-weaned calves: effects on health, locomotion and rest 68

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

vi

Contents

7 Group versus individual housing for un-weaned calves: behaviour and weight gain 72 8 Reflections on housing un-weaned calves individually, in groups and with cows 73 9 Conclusions 74 10 Where to look for further information 74 11 References 75 4 Genetic selection for dairy cow welfare and resilience to climate change 81 Jennie E. Pryce, Agriculture Victoria and La Trobe University, Australia; and Yvette de Haas, Wageningen UR, The Netherlands 1 Introduction 81 2 Selection indices 82 3 Selection for milk production, energy balance and fertility 83 4 New breeding objectives: health traits 86 5 New breeding objectives: dairy cows and climate change 91 6 Genomic selection, inbreeding and gene editing 92 7 Summary 96 8 Where to look for further information 96 9 Acknowledgements 97 10 References 97 5 Ensuring the welfare of culled dairy cows during transport and slaughter 103 Carmen Gallo and Ana Strappini, Animal Welfare Programme, Faculty of Veterinary Science, Universidad Austral de Chile, Chile 1 Introduction 103 2 Legislation and codes of practice 104 3 Pre-transport conditions that influence the welfare of cows during transport 106 4 Welfare of culled cows during transport 107 5 The effects of livestock markets on cow welfare 111 6 Welfare of cows at the slaughter plant 114 7 Conclusions 117 8 Where to look for further information 118 9 References 118 6 Ensuring the health and welfare of dairy calves and heifers 123 Emily Miller-Cushon, University of Florida, USA; Ken Leslie, University of Guelph, Canada; and Trevor DeVries, University of Guelph, Canada 1 Introduction 123 2 Newborn calf vitality 124 3 Colostrum management 129 4 Health management 131 5 Housing considerations 136 6 Feeding management 139 7 Managing weaned calves 142 8 Summary 145 9 Where to look for further information 146 10 References 146

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Contentsvii

Part 2  Nutrition of dairy cattle 7 The rumen microbiota and its role in dairy cow production and health 157 Anusha Bulumulla, Mi Zhou and Le Luo Guan, University of Alberta, Canada 1 Introduction 157 2 Diversity and function of rumen microbiota 158 3 Factors influencing composition of rumen microbiota 161 4 Current trends and innovations in studying the rumen microbiome: ‘omics’ approaches 163 5 Current trends and innovations in studying the rumen microbiota: linkage with host phenotypes 165 6 Altering rumen function by manipulating microbiota 168 7 Knowledge gaps and future directions 169 8 Conclusions 171 9 Where to look for further information 171 10 References 172 8 Biochemical and physiological determinants of feed efficiency in dairy cattle 181 John McNamara, Washington State University, USA 1 Introduction 181 2 The physiological and biochemical makeup of a dairy animal 182 3 Development of the research field: a brief overview 186 4 A case study on the biochemical determinants of feed efficiency 188 5 Mechanisms and effects of simple genetic variation 193 6 Summary and conclusions 195 7 Future trends in research 196 8 Where to look for further information 196 9 References 197 9 Feed evaluation and formulation to maximise nutritional efficiency in dairy cattle 199 Pekka Huhtanen, Swedish University of Agricultural Sciences, Sweden 1 Introduction 199 2 Evaluation of feed energy value 200 3 Alternative methods to predict digestibility and energy value 201 4 Discounts of digestibility and associative effects 205 5 Conversion of digestible nutrients to metabolisable energy and net energy concentration 206 6 Evaluation of feed protein value 207 7 Estimation of microbial protein 208 8 Determination of rumen undegraded protein (RUP) 210 9 Evaluation of feed protein systems 213 10 Summary and future perspectives 215 11 Where to look for further information 216 12 References 216 10 Sustainable nutrition management of dairy cattle in intensive systems 223 Michel A. Wattiaux, Matias A. Aguerre and Sanjeewa D. Ranathunga, University of Wisconsin-Madison, USA 1 Introduction 223 2 Phosphorus issues 224 © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

viii

Contents

3 Nitrogen issues 228 4 Carbon: a case study of enteric methane emissions and nutritional management in the intensive dairy production systems of California and Wisconsin 238 5 Conclusions 244 6 References 244 11 Nutrition management of grazing dairy cows in temperate environments 251 J. R. Roche, DairyNZ, New Zealand 1 Introduction 251 2 Economic factors affecting grazing system design 252 3 Using supplementary feed to manage pasture 253 4 Nutrition of grazing dairy cows: pasture as a feed 255 5 Choosing the right supplementary feed 260 6 Choosing the right genetics for a grazing system 262 7 Supplement effects on milk production 263 8 Practical nutrition management on the farm 265 9 Conclusions and implications 267 10 Where to look for further information 268 11 References 268 12 The use and abuse of cereals, legumes and crop residues in rations for dairy cattle 273 Michael Blümmel, International Livestock Research Institute (ILRI), Ethiopia; A. Muller, Research Institute of Organic Agriculture (FiBL), and ETH Zürich Switzerland; C. Schader, Research Institute of Organic Agriculture (FiBL), Switzerland; M. Herrero, Commonwealth Scientific and Industrial Research Organization, Australia; and M. R. Garg, National Dairy Development Board (NDDB), India 1 Introduction 273 2 Current and future levels of animal sourced food (ASF) production 274 3 Dairy ration compositions and current and projected feed demand and supply 276 4 Context specificity of feed demand and supply 282 5 Ration composition and ceilings to milk productivity 284 6 Optimizing the feed–animal interface: ration balancing in intensive and extensive dairy systems 286 7 Summary 290 8 Where to look for further information 290 9 References 291 13 Feed supplements for dairy cattle 295 C. Jamie Newbold, Aberystwyth University, UK 1 Introduction 295 2 Dietary buffers to control rumen acidity 297 3 Antibiotics for improved production 298 4 Fat supplementation 300 5 Immunological control of the rumen microbial population 303

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Contentsix

6 Plant extracts to manipulate rumen fermentation, boost production and decrease emissions 304 7 Direct-fed microbials, probiotics and exogenous fibrolytic enzymes 308 8 Other supplements to control GHG emissions 311 9 Conclusion 311 10 Where to look for further information 312 11 References 312 Part 3  Health of dairy cattle 14 Disorder of digestion and metabolism in dairy cattle: the case of subacute rumen acidosis 329 Gregory B. Penner, University of Saskatchewan, Canada 1 Introduction 329 2 Prevalence, aetiology and biological consequences of ruminal acidosis 330 3 Regulation of ruminal pH 333 4 The dogma of ruminal acidosis 341 5 Case study: SARA risk in the post-partum phase of the transition period 341 6 Other examples of SARA risk induced by low feed intake 345 7 Conclusion and future trends 346 8 Where to look for further information 347 9 References 347 15 Management of dairy cows in transition and at calving 353 Kenneth Nordlund, University of Wisconsin-Madison, USA 1 Introduction 353 2 Problems with using disease events to monitor herd transition management 355 3 Alternative data sources for monitoring herd transition management 355 4 Introduction to management factors that influence transition outcomes 358 5 Cow-level factors 359 6 Housing and environmental factors 364 7 Factors related to the decisions and actions of human caretakers 368 8 Case study: use of the transition cow risk assessment instrument 370 9 Summary and future trends 375 10 Where to look for further information 376 11 References 377 16 Causes, prevention and management of infertility in dairy cows 385 Alexander C. O. Evans, University College Dublin, Ireland; and Shenming Zeng, China Agriculture University, China 1 Introduction 385 2 Bovine parturition and uterine health 386 3 Bovine post-partum metabolic environment and ovarian activity 387 4 Oestrus in dairy cows 388 5 Establishing pregnancy in dairy cows 389 6 Heat stress and bovine fertility 391 7 Heifer fertility 392

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

x

Contents

8 Genetics and bovine fertility 393 9 Future trends and conclusion 393 10 Where to look for further information 393 11 References 394 17 Aetiology, diagnosis and control of mastitis in dairy herds 399 P. Moroni, Cornell University, USA and Università degli Studi di Milano, Italy; F. Welcome, Cornell University, USA; and M.F. Addis, Porto Conte Ricerche, Italy 1 Introduction 399 2 Indicators of mastitis: somatic cell count 401 3 Indicators of mastitis: non-cell inflammation markers 403 4 Contagious pathogens causing mastitis 404 5 Environmental pathogens: Escherichia coli, Klebsiella and environmental streptococci 407 6 Other pathogens: Prototheca, coagulase-negative staphylococci and other microorganisms 410 7 Management and control of mastitis 413 8 Dry cow therapy 414 9 The use of antibiotics 416 10 Where to look for further information 418 11 References 419 18 Preventing and managing lameness in dairy cows 431 Nick Bell, The Royal Veterinary College, UK 1 Introduction 431 2 Lameness in dairy cows: associated pain, prevalence and incidence 432 3 Recording causes and ensuring prompt and effective treatment 437 4 Lesion aetiology and categories of risk for the four main causes of lameness in dairy cows 443 5 Risk assessments and cost-effective interventions 446 6 Conclusions: how assessment, evaluation and facilitation is driving improvement 448 7 Where to look for further information 449 8 References 450 19 Control of infectious diseases in dairy cattle 457 Wendela Wapenaar, Simon Archer and John Remnant, University of Nottingham, UK; and Alan Murphy, Minster Veterinary Practice, UK 1 Introduction 457 2 The impact of infectious diseases 458 3 Principles of risk analysis and management 463 4 Hazard and risk identification 464 5 Risk assessment and evaluation 466 6 Risk management 471 7 Risk communication 475 8 Ensuring effective implementation 478 9 Trends in infectious disease control strategies 481 10 Conclusion 482

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Contentsxi

11 Where to look for further information 483 12 Abbreviations 483 13 References 484 20 Prevention and control of parasitic helminths in dairy cattle: key issues and challenges 487 Jacqueline B. Matthews, Moredun Research Institute, UK 1 Introduction 487 2 Helminth threats to grazing dairy cattle 488 3 Anthelmintic resistance 489 4 Progress in the development of evidence-based control programmes to reduce selection pressure for anthelmintic resistance 492 5 The development of robust diagnostics to support evidence-based control 493 6 Vaccine development 497 7 Future trends in research: contributions to enhanced and sustainable production 499 8 Concluding remarks 500 9 Where to look for further information 501 10 References 502 21 Genetic variation in immunity and disease resistance in dairy cows and other livestock 509 Michael Stear, Karen Fairlie-Clarke and Nicholas Jonsson, University of Glasgow, UK; Bonnie Mallard, University of Guelph, Canada; and David Groth, Curtin University, Australia 1 Introduction 509 2 Genetic variation in resistance to disease 512 3 The sources of genetic variation in resistance to disease 513 4 Strategies for breeding to increase resistance to disease 517 5 Case study 1: resistance to cattle tick infestation 520 6 Case study 2: mastitis in cattle 521 7 Case study 3: bovine respiratory disease (BRD) complex 522 8 Case study 4: additive and non-additive genetic variation 524 9 Conclusions 525 10 Where to look for further information 525 11 References 525 22 Responsible and sustainable use of medicines in dairy herd health 533 David C. Barrett, Kristen K. Reyher, Andrea Turner and David A. Tisdall, University of Bristol, UK 1 Introduction 533 2 Antimicrobial resistance 536 3 Inappropriate behaviours and practices 538 4 Making progress towards change 541 5 Delivering results 545 6 Future trends and conclusion 548 7 Where to look for further information 548

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

xii

Contents

8 Acknowledgements 548 9 References 548 23 Dairy herd health management: an overview 551 Jonathan Statham, Bishopton Veterinary Group and RAFT Solutions Ltd, UK 1 Introduction 551 2 The development of dairy herd health management (HHM) 552 3 Motivation for implementing HHM 554 4 Measuring: data for HHM 555 5 Monitoring: approaches to monitoring in HHM 561 6 Managing: delivering progress in HHM through planning, training and support for schemes 563 7 The potential benefits of HHM 565 8 Conclusions 567 9 Where to look for further information 567 10 References 568 Index571

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Series list Title

Series number

Achieving sustainable cultivation of maize - Vol 1 001 From improved varieties to local applications  Edited by: Dr Dave Watson, CGIAR Maize Research Program Manager, CIMMYT, Mexico Achieving sustainable cultivation of maize - Vol 2 002 Cultivation techniques, pest and disease control  Edited by: Dr Dave Watson, CGIAR Maize Research Program Manager, CIMMYT, Mexico Achieving sustainable cultivation of rice - Vol 1 003 Breeding for higher yield and quality Edited by: Prof. Takuji Sasaki, Tokyo University of Agriculture, Japan Achieving sustainable cultivation of rice - Vol 2 004 Cultivation, pest and disease management Edited by: Prof. Takuji Sasaki, Tokyo University of Agriculture, Japan Achieving sustainable cultivation of wheat - Vol 1 005 Breeding, quality traits, pests and diseases Edited by: Prof. Peter Langridge, The University of Adelaide, Australia Achieving sustainable cultivation of wheat - Vol 2 006 Cultivation techniques Edited by: Prof. Peter Langridge, The University of Adelaide, Australia Achieving sustainable cultivation of tomatoes 007 Edited by: Dr Autar Mattoo, USDA-ARS, USA & Prof. Avtar Handa, Purdue University, USA Achieving sustainable production of milk - Vol 1 008 Milk composition, genetics and breeding Edited by: Dr Nico van Belzen, International Dairy Federation (IDF), Belgium Achieving sustainable production of milk - Vol 2 009 Safety, quality and sustainability Edited by: Dr Nico van Belzen, International Dairy Federation (IDF), Belgium Achieving sustainable production of milk - Vol 3 010 Dairy herd management and welfare Edited by: Prof. John Webster, University of Bristol, UK Ensuring safety and quality in the production of beef - Vol 1 011 Safety Edited by: Prof. Gary Acuff, Texas A&M University, USA & Prof.James Dickson, Iowa State University, USA Ensuring safety and quality in the production of beef - Vol 2 012 Quality Edited by: Prof. Michael Dikeman, Kansas State University, USA Achieving sustainable production of poultry meat - Vol 1 013 Safety, quality and sustainability Edited by: Prof. Steven C. Ricke, University of Arkansas, USA Achieving sustainable production of poultry meat - Vol 2 014 Breeding and nutrition Edited by: Prof. Todd Applegate, University of Georgia, USA Achieving sustainable production of poultry meat - Vol 3 015 Health and welfare Edited by: Prof. Todd Applegate, University of Georgia, USA

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

xiv

Series list

Achieving sustainable production of eggs - Vol 1 016 Safety and quality Edited by: Prof. Julie Roberts, University of New England, Australia Achieving sustainable production of eggs - Vol 2 017 Animal welfare and sustainability Edited by: Prof. Julie Roberts, University of New England, Australia Achieving sustainable cultivation of apples 018 Edited by: Dr Kate Evans, Washington State University, USA Integrated disease management of wheat and barley 019 Edited by: Prof. Richard Oliver, Curtin University, Australia Achieving sustainable cultivation of cassava - Vol 1 020 Cultivation techniques Edited by: Dr Clair Hershey, formerly International Center for Tropical Agriculture (CIAT), Colombia Achieving sustainable cultivation of cassava - Vol 2 021 Genetics, breeding, pests and diseases Edited by: Dr Clair Hershey, formerly International Center for Tropical Agriculture (CIAT), Colombia Achieving sustainable production of sheep 022 Edited by: Prof. Johan Greyling, University of the Free State, South Africa Achieving sustainable production of pig meat - Vol 1 023 Safety, quality and sustainability Edited by: Prof. Alan Mathew, Purdue University, USA Achieving sustainable production of pig meat - Vol 2 024 Animal breeding and nutrition Edited by: Prof. Julian Wiseman, University of Nottingham, UK Achieving sustainable production of pig meat - Vol 3 025 Animal health and welfare Edited by: Prof. Julian Wiseman, University of Nottingham, UK Achieving sustainable cultivation of potatoes - Vol 1 026 Breeding, nutritional and sensory quality Edited by: Prof. Gefu Wang-Pruski, Dalhousie University, Canada Achieving sustainable cultivation of oil palm - Vol 1 027 Introduction, breeding and cultivation techniques Edited by: Prof. Alain Rival, Center for International Cooperation in Agricultural Research for Development (CIRAD), France Achieving sustainable cultivation of oil palm - Vol 2 028 Diseases, pests, quality and sustainability Edited by: Prof. Alain Rival, Center for International Cooperation in Agricultural Research for Development (CIRAD), France Achieving sustainable cultivation of soybeans - Vol 1 029 Breeding and cultivation techniques Edited by: Prof. Henry Nguyen, University of Missouri, USA Achieving sustainable cultivation of soybeans - Vol 2 030 Diseases, pests, food and non-food uses Edited by: Prof. Henry Nguyen, University of Missouri, USA Achieving sustainable cultivation of sorghum - Vol 1 031 Genetics, breeding and production techniques Edited by: Prof. Bill Rooney, Texas A&M University, USA

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Series listxv Achieving sustainable cultivation of sorghum - Vol 2 032 Sorghum utilisation around the world Edited by: Prof. Bill Rooney, Texas A&M University, USA Achieving sustainable cultivation of potatoes - Vol 2 033 Production and storage, crop protection and sustainability Edited by: Dr Stuart Wale, Potato Dynamics Ltd, UK Achieving sustainable cultivation of mangoes 034 Edited by: Prof. Víctor Galán Saúco, Instituto Canario de Investigaciones Agrarias (ICIA), Spain & Dr Ping Lu, Charles Darwin University, Australia Achieving sustainable cultivation of grain legumes - Vol 1 035 Advances in breeding and cultivation techniques Edited by: Dr Shoba Sivasankar et al., CGIAR Research Program on Grain Legumes, ICRISAT, India Achieving sustainable cultivation of grain legumes - Vol 2 036 Improving cultivation of particular grain legumes Edited by: Dr Shoba Sivasankar et al., CGIAR Research Program on Grain Legumes, ICRISAT, India Achieving sustainable cultivation of sugarcane - Vol 1 037 Cultivation techniques, quality and sustainability Edited by: Prof. Philippe Rott, University of Florida, USA Achieving sustainable cultivation of sugarcane - Vol 2 038 Breeding, pests and diseases Edited by: Prof. Philippe Rott, University of Florida, USA Achieving sustainable cultivation of coffee 039 Breeding and quality traits Edited by: Dr Philippe Lashermes, Institut de Recherche pour le Développement (IRD), France Achieving sustainable cultivation of bananas - Vol 1 040 Cultivation techniques Edited by: Prof. Gert Kema, Wageningen University, The Netherlands & Prof. André Drenth, University of Queensland, Australia Global Tea Science 041 Current status and future needs Edited by: Dr V. S. Sharma, Formerly UPASI Tea Research Institute, India & Dr M. T. Kumudini Gunasekare, Coordinating Secretariat for Science Technology and Innovation (COSTI), Sri Lanka Integrated weed management 042 Edited by: Emeritus Prof. Rob Zimdahl, Colorado State University, USA Achieving sustainable cultivation of cocoa - Vol 1 043 Genetics, breeding, cultivation and quality Edited by: Prof. Pathmanathan Umaharan, Cocoa Research Centre – The University of the West Indies, Trinidad and Tobago Achieving sustainable cultivation of cocoa - Vol 2 044 Diseases, pests and sustainability Edited by: Prof. Pathmanathan Umaharan, Cocoa Research Centre – The University of the West Indies, Trinidad and Tobago Water management for sustainable agriculture 045 Edited by: Prof. Theib Oweis, Formerly ICARDA, Lebanon Improving organic animal farming 046 Edited by: Dr Mette Vaarst, Aarhus University, Denmark & Dr Stephen Roderick, Duchy College, Cornwall, UK Improving organic crop cultivation 047 Edited by: Prof. Ulrich Köpke, University of Bonn, Germany

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Series list

Managing soil health for sustainable agriculture - Vol 1 048 Fundamentals Edited by: Dr Don Reicosky, USDA-ARS, USA Managing soil health for sustainable agriculture - Vol 2 049 Monitoring and management Edited by: Dr Don Reicosky, USDA-ARS, USA Rice insect pests and their management 050 E. A. Heinrichs, Francis E. Nwilene, Michael J. Stout, Buyung A. R. Hadi & Thais Freitas Improving grassland and pasture management in temperate agriculture 051 Edited by: Prof. Athole Marshall & Dr Rosemary Collins, University of Aberystwyth, UK Precision agriculture for sustainability 052 Edited by: Dr John Stafford, Silsoe Solutions, UK

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Preface ‘If you want to run a successful business, you have to look after your workers.’ These words were spoken by the director of a conspicuously successful dairy enterprise while standing among his workers, handsome, healthy, robust Friesian cows at pasture in in the South West of England. The three volumes in this collection review the science that underpins the successful management of successful and sustainable dairy production. Volume 1 reviews research on milk composition, genetics and breeding. Volume 2 discusses safety, quality and sustainability. Volume 3 reviews our scientific understanding underpinning the nutrition, health and welfare of all cattle in the dairy herd. In essence, Volumes 1 and 2 are about milk, Volume 3 is about cows. As I have written elsewhere (almost), ‘Understanding the dairy cow is a matter of heart and mind. It is essential to examine her scientifically as a complex and elegant machine for the production of milk, the nearest thing in nature to a complete food. It is equally essential to recognize her as a sentient creature with rights to a reasonable standard of living and a gentle death. In both senses of the word, this understanding is not static. The more we study the workings of the dairy cow, the more efficiently we can exploit her capacity to provide milk from grasses, cereals and an enormous range of plant by-products that we cannot or choose not to eat ourselves. The more we study her nutrition, health, behaviour and environmental requirements the better we can ensure her welfare and sustained performance’ (Webster 1993). The selection of chapters and specific topics for this book has been based on the central principle that efficient, quality milk production depends on healthy, contented cows, which further implies that good welfare requires a sense of wellbeing that is both physical and mental. If we are to promote this sense of wellbeing, we need at the outset, a proper understanding of cow behaviour and the motivations that govern behaviour. We need then to address each of the key elements of welfare by ensuring the necessary provisions. These are perhaps, most clearly and succinctly expressed by the ‘Five Freedoms and Provisions’ of the UK Farm Animal Welfare Council (FAWC 1993). 1 Freedom from thirst, hunger and malnutrition – by ready access to fresh water and a diet to maintain full health and vigour. 2 Freedom from discomfort – by providing a suitable environment including shelter and a comfortable resting area. 3 Freedom from pain, injury and disease – by prevention or rapid diagnosis and treatment. 4 Freedom to express normal behaviour - by providing sufficient space, proper facilities and the company of the animal’s own kind. 5 Freedom from fear and distress – by ensuring conditions that avoid mental suffering. Part I – Welfare of dairy cattle reviews our understanding of cow behaviour and considers their welfare needs in terms of housing and management as adults in the dairy herd, during development as young calves and heifers and in the special circumstances of transport and slaughter. A critically important chapter also examines the consequences of genetic selection with special emphasis on traits relating to soundness and sustainability: fertility, disease resistance and environmental impact. This complements the section in Volume 1 that considers genetics primarily in the context of productivity. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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The spectacular increase in milk production achieved through genetic selection has greatly increased demands on the modern intensively managed dairy cow. Indeed, it may reasonably be claimed that, in these circumstances, the capacity of the mammary gland to produce milk conspicuously exceeds the upstream capacity of the cow to provide it with nutrients. Part 2 – Nutrition of dairy cattle therefore places special emphasis on the new science that addresses the special problems associated with driving the digestive and metabolic processes at high speed. We review the Improved understanding of the nature of microbial digestion in the rumen that has led to the development of improved diets and feed additives designed to optimise nutrient supply and minimise the risk of disorders of digestion and metabolism. Special attention is given to management of high yielding cows in intensive systems to minimise two of the most important risks; rumen acidosis in lactating cows consuming large quantities of concentrate feed and the multiple physiological stresses associated with the transition period from late pregnancy to the onset of the next lactation. Part 3 – Health of dairy cattle deals first and at greatest length with the big three causes of ill health, poor welfare and impaired performance in dairy cows: infertility, mastitis and lameness. All of these should rightly be considered as production diseases, since their prevalence is irrefutably linked to management practices. Chapters in this section explore how the management of these conditions can be (and has been) improved through a combination of treatments based on new science, better understanding of aetiology and improved management through education and the implementation of well-designed herd health programmes. Applications of new science to the control of infectious and parasitic diseases include genetic selection for specific and non-specific elements of immunity and alternatives to antibiotics. We have it on reliable authority that new wine should not be put into old bottles. It may be equally unwise to invite an old scientist to review and edit new research. If this had been a book on the applications of molecular genetics, I would have been quite lost. However, it is all about living dairy cows: organisms that are highly complex but which have remained fundamentally the same for a long time. Over the last 50 years I have witnessed big shifts in fashion in dairy science. For many years, the emphasis was on increased milk production. Breeding for increased production per se has been very successful, though at significant cost in terms of infertility and productive life span. Attempts to increase performance through hormonal and other forms of biochemical manipulation have had little impact, partly through failure to anticipate public opinion and partly through failure to understand homeostasis. Research directed towards improved nutrition and digestive health has been, and continues to be, of enormous benefit to the health of dairy industry and the cows themselves. The reason for this is almost too obvious to mention. Whereas the metabolism of an individual animal operates within strictly controlled limits, the potential for manipulating feeds and feed mixtures to optimise nutrient supply while ensuring healthy digestion is almost limitless. The campaign for good health can never be entirely won. The most newsworthy problems arise from the appearance of new or re-emergent epidemics such as Foot and Mouth disease, but over time these do not begin to compare with the big three: infertility, mastitis and lameness. Here we have needed the best of science simply to hold the line in the face of increasing challenges arising from the environment and management. Most recently, scientists have been presented with new problems associated with the impact of dairy production systems on the sustainability of the living environment, in particular those associated with high output of carbon (especially methane) and nitrogenous compounds. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Prefacexix

They receive proper attention here. However, in our enthusiasm for this new science, we should never overlook the fact that these are two of the key elements of life. The poison is only in the dose. John Webster References Farm Animal Welfare Council. 1993. Second Report on Priorities for Research and Development in Farm Animal Welfare, MAFF, Tolworth UK. Webster John. 1993. Understanding the Dairy Cow, 2nd ed. Blackwell Scientific Publications, Oxford UK.

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Introduction Cow’s milk is one of the world’s most important agricultural food products. Its importance in the diet is widely acknowledged as a source of calcium, protein, vitamins and minerals. It is an essential ingredient in a wide range of foods. Demand is increasing, particularly in developing countries as a result of growing populations, increasing urbanisation and income levels as well as changes in diet. In meeting demand, more intensive dairying systems in developed countries face a range of challenges such as maintaining high standards of safety in the face of the continuing threat from zoonoses and contaminants entering the food chain, whilst continuing to improve nutritional and sensory quality. At the same time farms need to become more efficient and sustainable by using fewer inputs and reducing greenhouse gas emissions. It is essential that farming must also meet higher standards of animal health and welfare. Smallholder systems in developing countries face problems such as poor nutrition for cattle, low productivity and vulnerability to disease which impact on safety, quality, sustainability and animal welfare. Drawing on a range of international expertise, the three volumes of Achieving sustainable production of milk review key research addressing these challenges. Volumes 1 and 2 review research on the quality and safety of milk, genetics and sustainability. This volume reviews the current state of our scientific understanding of the nutrition, health and welfare of cattle in the dairy herd.

Part 1  Welfare of dairy cattle In recent years we have developed the necessary tools to gain a much deeper understanding of cow behaviour in intensive management systems. This improved understanding can facilitate the design of new, sustainable management systems which promote cattle welfare. Chapter 1 summarises current research on cattle preferences and behaviour. It considers the importance of understanding the perceptual world of cows, and then how the preferences and emotions of cows are revealed through their social, nutritional and reproductive behaviour, their movements (locomotion and resting) as well as their responses during transport and slaughter. Research to identify cows’ emotional responses to increasingly artificial environments facilitates the identification of systems that are more conducive to high levels of welfare. Building on Chapter 1, Chapter 2 provides an overview of key issues in the welfare of dairy cattle, providing a context for the following chapters in Part 1. These issues include: housing (with potential problems of confinement and restricted movement, for example), the consequences of a unilateral focus on milk yield in areas such as breeding (with implications for health), poor handling of cattle (for example in transport and slaughter), as well as disrupted social structures (for example in the treatment of heifers and calves). It reviews controversies about reconciling what we know about the natural social behaviour of cattle with the demands of more intensive production systems, and suggests priorities for future research. In modern dairy farming, lactating cows and un-weaned calves are often housed indoors, in a restricted space, at high density, and/or separate from other animals. Such

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Introductionxxi

housing conditions affect the welfare of the animals by creating risks of illness and injuries and placing restrictions on behaviour. Picking up from Chapter 2, Chapter 3 examines the physical and social aspects of dairy cattle housing. It focuses on the different housing systems available for lactating cows, and the advantages and disadvantages of these alternatives. Topics discussed include stall design, flooring and stocking densities in relation to social competition and dominance within herds. The chapter then reviews the issue of housing for un-weaned calves. It discusses how housing affects weight gain, health and aspects of behaviour such as locomotion and rest, as well as the implications of housing un-weaned calves individually, in groups or with their mothers. As identified in Chapter 2, narrow breeding goals focussed on milk production traits have been detrimental to the reproductive performance and health of dairy cattle. There is therefore a need to develop breeding strategies which allow production and nonproduction traits to be balanced against each other. Chapter 4 discusses the principles behind multi-trait selection. It reviews practices of selecting for milk production, energy balance and fertility, and then consider ways of incorporating newer breeding objectives such as health traits, feed efficiency and reduction of methane emissions, as well improving heat tolerance in cattle in the face of a changing climate. The chapter concludes by discussing the use of modern genomic selection and gene editing techniques. As the chapter points out, while genomic selection has been implemented for many traits (such as fertility and longevity), there are still obstacles to overcome in applying it to other traits of interest, associated with the heritability of the trait, the number of animals in reference populations and the cost of phenotyping. These provide priorities for future research. Each year, some cows are culled from dairy herds. Most of these cows are culled due to sickness or lameness, meaning that they are likely to experience pain and distress during marketing, transport and slaughter. Chapter 5 reviews strategies for ensuring the welfare of these cows both before and during transport as well as slaughter. The chapter summarises the legislation and codes of practice surrounding the transport and slaughter of cows, considers important pre-transport conditions which can affect the welfare of cows during transport and at the slaughterhouse. It also discusses causes and signs of distress as well as strategies to avoid welfare problems. National survey results suggest that approximately 1 out of every 10 dairy heifers in the United States die before weaning. Such statistics highlight the potential for improvements in the rearing of young dairy calves. Chapter 6 reviews strategies for managing calving, improving calf vitality and successful colostrum feeding. It also assesses prevention of neonatal disease, alleviation of pain during common procedures and provision of optimal housing. Finally, it discusses execution of accelerated feeding programs, stress-free weaning, and maintenance of efficient rearing by optimal nutrition and housing of postweaned dairy heifers. In each case, the chapter both identifies key advances in improving calf health and welfare, as well as remaining hurdles to achieving meaningful improvements in the success of heifer rearing programs, particularly as they relate to calf welfare.

Part 2  Nutrition of dairy cattle Nutrition is a key element in the efficiency and sustainability of milk production as well as in cow health and welfare. This is the subject of the chapters in Part 2. Ruminants are characterized by their capacity for pre-gastric anaerobic fermentation in the rumen

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Introduction

(foregut), which harbors a variety of microbes including bacteria, archaea, protozoa and fungi. The complex association of different microbes acts synergistically for the conversion of cellulosic feed into volatile fatty acids (VFAs) and proteins that fulfill the nutrient requirements of the animals. Chapter 7 summarizes current knowledge about rumen microbial diversity, ecology, function, and relationships with host phenotypes. It also reviews research on factors influencing composition of rumen microbiota and how this understanding can be used to alter microbiota to improve rumen function. As it points out, advanced sequencing-based technologies have led to the detailed identification of rumen microbiota/microbiotome at both taxonomic and functional levels, providing new insights into the role of the rumen in ruminant production and health. A range of biochemical and physiological factors affects feed efficiency in dairy cattle. Chapter 8 provides an overview of the physiology and biochemistry of the cow, and then focuses on what we know about the biology of lactation, with particular emphasis on the effects of genetic variation on nutrient intake metabolism. The chapter shows the role of biochemical metabolic models in exploring the effect of genetic selection or genetic variance on feed efficiencies. The chapter also includes a case study looking at the mechanisms and effects of simple genetic variations which have been shown to have a significant impact on feed efficiency. The models described in Chapter 8 play a role in accurate assessment of the nutritional value of feeds, which is essential in the formulation of diets and evaluation of different feeds. Chapter 9 discusses different methods of estimating digestibility, energy and protein value of dairy cattle feed formulations. Topics include evaluation of feed energy value and methods to predict digestibility and its effect on energy value. The chapter then assesses discounts of digestibility and associative effects and ways of calculating metabolisable energy (ME) and net energy concentration (NE). The chapter also reviews ways of evaluating protein value, including estimation of microbial protein and rumen undegraded protein (RUP). The chapter summarises the advantages and weaknesses of static empirical models and dynamic mechanistic models, emphasizing the need to evaluate models using large datasets from productions studies to improve the accuracy of predictions of nutrient efficiency. Managing dairy herd nutrition must not only meet the nutrient requirements of the animals but also contribute to the overall sustainability of dairy farm operations. As Chapter 10 points out, research to reduce enteric methane emission through feeding strategies is an important element in improving the efficiency of conversion of feed to milk, particularly with the use of a wider range of by-products such as distiller’s grain in dairy rations. Chapter 10 discusses the use and importance of phosphorus and nitrogen in cow nutrition, their broader environmental impact, and a range of sustainable solutions to reducing that impact. The chapter also explores the overall carbon footprint associated with dairy farming. It includes a case study of using nutrient management to reduce enteric methane emissions in intensive dairy production systems in California and Wisconsin. Chapter 11 reviews pasture-based systems for dairy production. When properly managed, grass-legume mixes can provide well balanced nutrition able to sustain good levels of milk production in dairy cattle so that cows need only be fed non-pasture feeds when there is insufficient pasture. To achieve good nutrition management in grazing systems, it is essential to identify genuine feed deficits to optimise pasture use and minimise reliance on supplementary feeds. As Chapter 11 points out, getting this balance right can have more impact on costs than deciding on the type of supplement to be fed. The chapter reviews the factors which must be taken into account when deciding © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Introductionxxiii

whether and how to supplement pasture with additional feed, as well as choosing the right supplementary feed to use. The production of animal feed requires a significant use of resources which reduces the sustainability of dairy farming operations. When choosing feed sources and feeding methods, it is therefore essential to consider context-specific trade-off analyses, and to take into account the relationships between use of natural resources, feed products and the livestock in question. Chapter 12 reviews key elements in trade-off analysis in making better use of existing feed resources and producing more feed biomass of higher fodder quality. It looks at current and future levels of animal sourced food (ASF) production, the relationship between feed ration composition and milk productivity, and methods of ration balancing in intensive and extensive dairy systems. The manipulation of ruminal fermentation to maximize the efficiency of feed utilization and increase ruminant productivity is of great commercial interest. Building on Chapter 7, Chapter 13 reviews the ways of manipulating rumen fermentation in dairy cattle. It considers a wide variety of approaches, looking in each case at potential benefits and limitations. Approaches include the use of dietary buffers, antibiotics and fat supplements as well as immunological control of the rumen microbial population. It also discusses the use of plant extracts to manipulate rumen fermentation, boost production and decrease emissions. Finally, it summarises research on direct fed microbials, probiotics and exogenous fibrolytic enzymes.

Part 3  Health of dairy cattle The final group of chapters looks at key aspects of the health of dairy cattle. Picking up on the discussion of nutrition in Part 2. Chapter 14 starts by considering one of the main disorders of digestion and metabolism in dairy cattle: subacute rumen acidosis (SARA). Given the high milk yields required of current dairy cattle, feeding energy dense diets is necessary to meet nutrient requirements. Typically, this entails the use of diets that are highly fermentable. However, excessive fermentation in the rumen decreases ruminal pH and leads to the onset of ruminal acidosis. The chapter explores current research on the nature, causes and prevention of SARA. As the chapter points out, management strategies that ensure adequate and consistent dry matter intake (DMI), while balancing fermentability of the diet, are most likely to ensure high milk yield while mitigating undue risk for SARA. An essential event in dairying is the birth of a calf and the transition of the mother cow from gestation and into lactation. While the transition can proceed without incident, it is also a period of substantial risk for many cows. As Chapter 15 points out, most of the clinical disease events in a diary cow’s life occur during the transition period. It is believed that almost all cows experience some immune dysfunction during the peripartum period, and that this combined with nutritional and other issues leads to a variety of metabolic and infectious disease events. Chapter 15 addresses the best way to monitor the health and management of cows during the transition period. It discusses a number of factors which can affect herd transition health, including the intrinsic characteristics of the cows, limitations and challenges associated with the housing and environment in which cows are placed, and the role of husbandry. The chapter concludes with a case study on the use of transition cow risk assessment (TCRA) techniques in a dairy operation.

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Introduction

Reproduction and fertility are central components to successful dairy enterprises and the appropriate management and understanding of the physiological events needed for fertility is crucial to sustainable dairy farming. Chapter 16 discusses the physiology of the main impediments to fertility as well as the management issues that need to be addressed in order to ensure good fertility of dairy cows. It deals with parturition and uterine health, the importance of the post-partum environment and the role of oestrus, as well as methods of establishing pregnancy and the effect of heat stress on cows’ fertility. The chapter also examines fertility of heifers and the impact of genetics on fertility. Mastitis is one of the most economically important diseases in dairy production. Associated costs include treatment, culling, decreased milk production and quality. Cow welfare is also compromised. Chapter 17 reviews the indicators of mastitis and the contagious and environmental pathogens which cause it, including Escherichia coli, Klebsiella, streptococci, Prototheca, Coagulase-negative staphylococci and other pathogens. It then discusses how mastitis can be managed and controlled on dairy farms, including good farming practices to management the cattle environment (such as appropriate bedding to minimize contamination and spread of disease). There is a particular focus on the use dry cow therapy and the appropriate use of antibiotics. Lameness in dairy cows is a major economic and welfare problem worldwide. Despite its importance, there are still significant gaps in research, particularly in disease pathogenesis, treatment and herd interventions. However, appropriate surveillance can make a substantial difference to ensuring prompt and effective treatment. Key methods include quantifying lameness levels, analysing recorded lesions causing lameness, evaluating risk factors and prioritising interventions. Chapter 18 reviews what we know about lesion aetiology and categories of risk for the main causes of lameness in dairy cows. It also assesses the evidence underpinning what makes effective control programmes for the prevention and management of lameness in dairy cows. Chapter 19 describes developments in infectious disease control in the dairy cattle industry. A risk analysis approach is presented as a framework for managing infectious disease at both global and farm level. The chapter introduces the principles of risk assessment and management, discusses hazard and risk identification as well as risk assessment and evaluation. It then considers methods of risk management and risk communication. The chapter highlights the importance of issues such disease detection, the use of diagnostic tests and their appropriate interpretation. The range of impacts of infectious disease on the dairy industry is described as well as ways to evaluate the risks they present. The chapter also discusses key challenges in successful implementation and effective communication of risk management on dairy farms. Parasitic helminth infections are one of the most important causes of production loss in livestock worldwide. Grazing dairy cattle are exposed to various worm species, all of which can impact health, welfare and productivity to varying degrees. For several decades, helminth control relied primarily on the frequent use of broad spectrum anthelmintics. However, the use of such treatments needs to be moderated in order to avoid selection pressure for anthelmintic resistance. Chapter 20 describes the likely helminth threats to grazing dairy cattle, with particular emphasis on the issue of anthelmintic resistance. It then offers a review of progress in developing evidence-based control programmes to reduce selection pressure for anthelmintic resistance. Finally, it reviews progress in the development of anti-helminth vaccines. Such vaccines are a long way off commercial availability, but recent progress suggests that these could form part of a sustainable solution to helminth control on dairy farms. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Introductionxxv

There is considerable variation in resistance to disease in livestock that enables the effective selection of healthier and more productive animals in breeding. Chapter 21 reviews what we know about the sources of variation in resistance to disease in cattle. It then considers three strategies for selecting for resistance. The first approach is by selecting for resistance to particular diseases. A second technique is selecting for animals with strong innate and or adaptive immune responses to achieve a broad-based disease resistance. A final approach is selecting for animals that perform well in an environment in which disease is endemic. The chapter illustrates these differing approaches with three case studies looking at improving resistance to cattle tick infestation, mastitis and bovine respiratory disease (BRD). The chapter also reviews additive and non-additive genetic variation, as well as new technologies such as high density SNP chips and techniques like genome-wide association studies (GWAS). As well as having an obligation to safeguard animal health and welfare, veterinarians and dairy producers also have responsibilities to protect human health from the risk of antimicrobial resistance and the food chain from medicine residues. Chapter 22 describes typical regulatory controls for veterinary medicines and current antimicrobial use in dairy production. Echoing themes in Chapters 18, 20 and 23, it argues for the need for change in the way we view and use medicines. The chapter proposes how medicine prescribing practices might be changed in the dairy industry. As an example, integrating a detailed review of actual medicine use on-farm into health planning is an effective way of reducing the numbers of animals treated, as well as ensuring that when treatments are required they are applied appropriately. This approach can greatly enhance the farmer-veterinarian working relationship, whilst making preventive medicine a reality. It enhances animal health while reducing both medicine costs and the risk of antimicrobial resistance. Using this kind of approach, the chapter also shows how key antimicrobials could be phased out over a relatively short period of time, whilst simultaneously improving animal health, welfare and milk production. The importance of ensuring animal welfare and food security, of combating antimicrobial resistance (AMR), and of increasing food production, all contribute to the need for preventative medicine. Herd health management (HHM) involves the delivery of a more co-ordinated approach where management interventions are prioritized and the veterinary surgeon acts as a central hub for the farm team. Chapter 23 reviews the principles and development of HHM. It then discusses the key steps in effective implementation, starting with data collection and measurement. It then summaries monitoring techniques before looking at management, including planning, training and support HHM for schemes. Finally, the chapter looks at the benefits of HHM in improving animal health whilst reducing costs and reliance on antibiotics.

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Part 1

Welfare of dairy cattle

Chapter 1 Understanding the behaviour of dairy cattle C. J. C. Phillips, University of Queensland, Australia 1 Introduction 2 Studying the preferences of cattle: an overview 3 Cattle perception 4 Social, nutritional and reproductive behaviour 5 Locomotion and resting 6 Behaviour during transport and slaughter 7 Conclusions 8 Future trends 9 Where to look for further information 10 References

1 Introduction Cattle evolved in the developing grassland regions of India 2 million years ago (van Vuure, 2005). Their ungulate niche was the forest fringes, where grassland and trees combined and they could take advantage of both as food sources. Although humans slaughtered all remaining Bos primigenius cattle about 500 years ago, still there remain some wild cattle that are closely related to them in south Asia, in particular the gaur cattle (Bos gaurus) (Fig. 1). Gaur cattle still occupy the forest fringes of India and Malaysia, browsing and grazing as their common ancestors with the European cattle, Bos taurus, would have done. Study of the behaviour of these close relatives of domestic cattle would increase our understanding of the needs of Bos taurus cows. The digestive system of cattle is designed for consumption of large quantities of fibrous forages that are conveyed into a fermentation vessel in the form of their modified stomach, the rumen, where microorganisms break down fibrous food over long periods of time. They evolved the capacity to regurgitate their feed into their buccal cavity. There they chew it over long periods of time (ruminating), often for as long as 8 hours per day. This helps to comminute the fibre particles to increase the surface area exposed to microorganisms and adds large quantities of saliva essential to buffer the acidic end products of microbial digestion. Cattle usually ruminate while lying down, and the need to maintain a regular flow of nutrients to the rumen for optimal microbial population

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4

Understanding the behaviour of dairy cattle

Figure 1 Gaur cattle that live in the forest fringes of Malaysia and India.

growth led to their ruminating at times when they were resting in between feeding bouts. Concentrated feeding periods occur at dawn and dusk to avoid feeding at night when the predation risk is elevated. Cattle have been domesticated for about 9000 years, and before that, primitive man hunted cattle extensively. For millennia, people have been studying cattle behaviour, particularly with a view to being able to predict their responses. However, this does not mean that we understood the reasons why cattle behave in specific ways well, and it is only very recently that we have been developing tools to study this. Eventually, this should enable us to manage cattle behaviour so that the animals have a life worth living. However, John Webster has provided us with a realistic assessment of our current ability to determine dairy cows’ emotions. ‘We must acknowledge that our interpretation of the feelings of others can only be subjective. Since I can never be entirely sure how you are feeling, I am reluctant to speak with authority on the mental state of a dairy cow’ (2016). Up until recently we have mainly had to use our intuition, based on an anthropomorphic assessment, to understand cattle behaviour. However, cattle are unlike us in many ways; in fact, one of the only characteristics shared is that of being a terrestrial mammal. Cattle evolved as prey, we as predators; they as crepuscular herbivores, we as diurnal omnivores; they as quadrupeds, ourselves as bipeds; they with olfaction as a primary communication method, ourselves with vocalisation for this purpose; they have significant sexual dimorphism, we have much less; they have the ability to vary their pelage to meet environmental conditions, we do not. Understanding the reasons for cattle behaviour is important if we want to provide good conditions for their welfare, as judged from the animal’s perspective, particularly when we keep them in conditions far removed from the ecosystem for which they evolved. Humans have chosen cattle to accompany them, as a primary food producer, to almost all parts of the globe, where they have to cope with great variation in climate. Unlike the other major food producers, poultry and pigs, we do little to modify their environment to suit their needs, and we expect them to thrive in environments as diverse as mountain pastures and feedlots. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Understanding the behaviour of dairy cattle5

2  Studying the preferences of cattle: an overview Cattle behaviour is driven by their emotional responses to their environment. These provide the means for them to learn how to respond to changes in their environment, that is, how to behave. The tools at our disposal to examine the emotions of cattle have been developed mostly in the last twenty years. Before embarking on complex tests of cows’ preferences, it is important to understand the perceptual world of cattle, in particular their vision, olfaction and gustation. For example, before testing the effects of different lighting conditions on the behaviour of cattle, their ability to distinguish different colour and intensity of different light sources should be understood (e.g. Phillips and Weiguo, 1991; Phillips and Lomas, 2001). Then, having gained an understanding that cattle have less ability than us to distinguish luminaires of varying intensity, or between the colours blue and green, but have a much broader field of vision, different lighting regimes can be developed and tested for their impact on behaviour. The knowledge that long wavelengths of light (red colours), as well as being less well perceived, stimulate activity, should deter us from using this form of artificial light in highly stocked cattle sheds. At the same time, it is important to consider the aetiology of their behaviour, and its adaptive benefit. In this respect, the ability of cattle to distinguish red from green may have had adaptive benefit in helping them to detect injured cattle that are bleeding, or cows in oestrus with reddened vulvas. Simple choice tests, where cattle have the opportunity to choose features of their environment, can also provide useful information on the optimum environment. However, they can be misleading; to use another lighting example, cattle given the opportunity to choose a lit or dark environment selected to have lights on for 54% of each 24 h day (Phillips and Arab, 1998). This could be interpreted as an ambiguous response: they did not really care whether the lights were on or not. Or it could be interpreted as cattle preferring to spend 54% of their time in the light. To overcome this problem of interpretation of choice tests, it is often necessary to compare their preference for different resources or devise methods that require them to work to obtain the resources. Furthermore, individuals may vary considerably in their preferences, which must be taken into account when devising cattle environments. For example, cubicle (free-stall) housing can be uncomfortable for big cows, as well as causing abrasion on their hocks; hence, it is important to ensure that at least some cubicles will accommodate the biggest cows in a herd. These cows will naturally be the most dominant ones and they should, therefore, be able to preferentially choose these cubicles. Such opportunities for a variety of preferences are important in any modern cow facility if welfare is to be properly afforded to all cows, not just the average cow. Measurement of physiological responses can augment our understanding of the behavioural responses of cattle to different environments. Cortisol, as the principle hormone implicated in the hypothalamo-pituitary-adrenal (HPA) axis responses of cattle to stress, has been evaluated in response to a variety of welfare situations. However, it must be remembered that this axis is activated in specific circumstances relating to stress, not in all situations in which welfare is adversely affected by the animal’s environment. Thus, although cognitive bias tests (described below) indicate that separating calves from their mother makes them more pessimistic (Daros et al., 2014), early research provided physiological evidence, suggesting that the HPA axis is not activated (Hopster et al., 1995). More recent research has led to elaboration of calves’ responses, outlined below

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(Hernandez et al., 2014), demonstrating the danger in drawing conclusions from isolated pieces of research. Furthermore, although elevated cortisol, indicating activation of the HPA axis, is evidence of exposure of cattle to stress-inducing conditions, prescribing critical concentrations is not currently possible with any degree of certainty. Heart rate is another physiological parameter that can help us to understand the response of cattle to their environment (von Borell et al., 2007). Stress elevates heart rate, for example removing calves from their dam (Hopster et al., 1995), and over prolonged periods of elevated heart rate there will be reduced variability in this parameter. The responses are predictable, at least within individuals, and it may be possible to identify whether the sympathetic or parasympathetic nervous system has been aroused. These have antagonistic influences on the sinoatrial node of the heart, regulated by noradrenaline and acetylcholine, respectively. However, caution and further research is required as the relationships with heart rate variability are complex, probably not linear and may be specific to individuals (Goldberger et al., 2001). Recently, tools have been developed to explore the emotions of cattle more directly, through a detailed knowledge of their behaviour. Cognitive bias tests work on the principle that the time cattle take to investigate uncertain, or ambiguous, cues is related to their overall level of confidence. Thus, we may conclude that when cows take longer to investigate ambiguous food cues after they have had their calf removed they are depressed (Daros et al., 2014). Providing an even more direct window into the emotions of cattle, lateralisation of their eye gaze during interactions with other cattle or humans can indicate whether they view the other animal as fearful or benign (Robins and Phillips, 2010; Phillips et al., 2015). Flight and fight responses (e.g. to predators) are processed in the right brain hemisphere, which is connected to the left eye, whereas abstract, long-term and planned tasks are processed by the left hemisphere, which is connected to the right eye. Unlike humans, cattle use their left or right eyes depending on the perceived level of threat, which may be one reason why we usually handle them on their left side, so that they are able to keep us in their left eye field of vision. A forced lateralisation test (Phillips et al., 2015) to detect anxious and subordinate cows uses an unfamiliar person standing in the middle of a lane down which cows walk after being milked, with these cows being more likely to pass the person on the right side, viewing the person in their left eye.

3  Cattle perception The perceptive faculties of cattle differ from those of humans in many ways, which is relevant to our ability to understand cattle behaviour from an anthropomorphic perspective. Positioning their eyes on the sides of their head enables them to spot predators approaching from behind; their field of vision spans 330o, compared with our own 180o. Their large eyes give them good vision in low light intensities. They have an elongated pupil and ‘area centralis’ on their retina, with a high concentration of photoreceptors, compared with our own round pupil and fovea. This provides them with excellent vision on the horizon and an ability to detect movement in vertical and horizontal planes, but limited ability to focus on nearby objects. Because of the stated facts cows appear somewhat clumsy in a crowded cubicle house. Cows’ ears are large and motile, pointing downwards when they are sad, stressed or upset but erect at other times. They hear high frequency sounds, such as predatory bats or insects, much better than us, but are considerably worse at localising

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Understanding the behaviour of dairy cattle7

sounds. Their sense of smell is extremely acute; in open grassland they needed to use covert communication if there was a risk of predation. The pheromones generated in their body fluids are used to communicate many different emotions, such as fear and sexual receptivity.

4  Social, nutritional and reproductive behaviour 4.1  Social behaviour The need for cattle to spend long periods resting to digest the relatively fibrous feed that they consume, and their heavy gut contents, leaves them vulnerable to predation, particularly at night. They have little ability to run for long distances to escape, rather a risk of predation encourages cattle to group together to protect themselves, if necessary by forming a circle with their horns facing outwards. Alternatively, they hide from predators in long grass or in trees, especially young calves that form themselves into ‘creches’, often with an adult cow keeping guard. These behaviours can still be observed in extensively kept cattle, in alpine regions, for example. In the ontogeny of cattle, social behaviour is important to facilitate aggregation, which reduces predation by concentrating potential prey into an easily defendable area and increasing the efficiency of surveillance by one or two animals that are on guard to detect the presence of predators. Isolated animals quickly become stressed. The social structure of the herd is maintained by regular communication among herd members, for example use of their tail or ears to convey emotions, which can be held erect or relaxed down depending on the animal’s mood. Generally, these indicate negative emotions when held in the relaxed position and positive emotions or alertness when held erect. Such visual signalling is safer than vocalisation in a species that evolved with a constant risk of predation. Cattle also use the pheromones referred to above, as another covert signalling mechanism, to signal fear, sexual receptivity or arousal. High-pitched vocal communication is usually reserved for extreme arousal, such as when cow and calf are separated, cows are in oestrus, or bulls are separated from the cows in a herd by a fence or hedge. Cow–calf separation is followed by calls from both that are recognised by the other (de la Torre et al., 2016). Communication by touch is evident in the form of long periods of time spent in mutual grooming. As well as this allogrooming, cows are motivated to groom themselves, which in intensive dairy housing systems may be facilitated by the provision of a rotating brush. Cows are less likely to use this when they are stressed, because of poor health or other environmental reasons, giving potential to monitor its use by individual cows to detect stress levels (Mandel et al., 2013). Social behaviour is evident in mother–calf relationships. Although this would be expected to begin in utero, little is known about the interactions at that time. Although calves are born in a relatively precocious state, because of predator risk in their phylogenetic history, they maintain close contact with their mother, but not father, and they naturally take their place in a matriarchal family group. In most farming systems, calves are separated from their dams early to allow the latter to produce milk for human consumption. The separation causes a negative mood in the calves (Daros et al., 2014), and we now know that there is an almost immediate increase in cortisol in the cows, demonstrating stress (Hernandez et al., 2014), despite the research of Hopster et al. (1995) referred to earlier. Early separation

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reduces the stress to the calf, as measured by heart rate variability (Clapp et al., 2015), and so does weaning and separating the calves from their mothers at different times. This can be done by fitting a nose flap, which allows them to temporarily stay with the cow but not suckle (Loberg et al., 2008). The cow–calf bond is learnt over time and appears to be weaker in intensely selected dairy breeds, such as the Hostein Friesian, compared with beef breeds (Le Neindre, 1989 a,b). As a young calf develops, play forms an increasingly important part of its repertoire, despite the energy cost and risks. Defined as ‘structural transformations and functional rehearsals or generalisations of behaviours or behavioural sequences’ (Fagen, 1981), it usually includes physical and/or mental elements, preparing the calf for adult life. Physical play begins in utero, in the form of kicking, rotation and practice movements towards the birth canal, serving to get the foetus ready for parturition and postnatal life (Phillips, 2002; Verbruggen et al., 2016). Other forms of play in utero include nervous reflexes, often detectable by veterinarians searching for signs of life (Jackson, 1995). Later, play is used to increase strength, endurance and survival skills. Play behaviour is stimulated by novel environments, where it serves a cognitive function, developing calves’ understanding of their surroundings. It also has a cohesive function, bringing calves together, which would help to keep them safe from predators that might pick off an individual animal. However, some types of play are associated with barren, monotonous environments, for example tongue playing in veal calves, but this may also be associated with a monotonous diet with inadequate fibre. The differential responses suggest that there may not be a universal phenomenon of play, rather a series of variously motivated behaviours. As cattle are a highly social species, with competition for access to resources, in particular mating partners, there has to be a mechanism to ensure that fighting is kept to a minimum. This mechanism is the dominance hierarchy. Within a herd, cattle know their position in relation to priority to access any resource that is limited in supply. Often in indoor housing systems this is space, and the hierarchy means that a subordinate cow can pass a dominant cow with just a simple acknowledgement of their relative positions in the hierarchy, a deferent lowering of the head usually. This hierarchy allows just a few dominant bulls, usually the largest, older and more experienced ones, to sire most of the calves in a large herd of naturally mated cows. The hierarchy operates out at pasture, as well as indoors, so that the dominant cows have access to the best pasture and often give the most milk. When moving as a herd, dominant cows usually position themselves in the middle, to protect themselves from danger, which the leaders might confront first, and to gain access to resources before the stragglers at the back. In more relaxed situations, at grazing or in cowsheds, cattle can be approached, by other cows or humans, to within a predictable distance before they flee. This ‘flight distance’ is typically about 2 metres in dairy cows that are used to people, although it does depend somewhat on the speed of the approach and familiarity of the person or cows approaching and the space availability to the herd. Cows have a good memory of their herdmates and people handling them, and abuse by stockpeople is remembered for a very long time. Cows that were brought up together as calves often remain friends throughout their lives, such is the strength of social bonding in the species. They can be seen lying together and also being milked together. In the grazing situation, cows maintain a constant distance to their nearest neighbours and then move in concert up and down a field. Weather conditions influence this movement, as they prefer to graze with their backs to wind and driving rain. The strict hierarchy in a herd explains why cows get stressed when stockpeople disrupt the structure of a herd, by mixing groups for example, or moving cows among groups © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Understanding the behaviour of dairy cattle9

according to their milk yield. Cows need regular, consistent and calm management and disruptions to this usually result in reduced milk production. Stockpeople need a close rapport with their cows to get a regular supply of high-quality milk. This may include stroking and patting them, talking to them and rewarding good behaviour; never punishing them by hitting, kicking and other such ill treatments. At the same time the herdsperson has to be respected by the cows, and effectively operates as the lead ‘cow’ in the herd, a position which is only gained by consistent benign treatment. The principles of ‘low stress stock handling’ are gaining widespread acceptance worldwide as a means to move cattle benignly, safely and quickly (Grandin, 1989).

4.2  Nutritional behaviour Cattle show considerable flexibility in their nutritional behaviour, being able to consume their daily requirements in just 4 or 5 h if the feed is in a conserved form and presented in a trough or bunk, or grazing for 13 h if they are kept on short pasture. A grazing cow will bite the pasture about 36 000 times each day (Phillips and Leaver, 1986). Depriving cows of the opportunity to bite grass or other fibrous feed by offering a highly concentrated diet may frustrate a strong motivation, as oral manipulation of feed is a behavioural need (Lindstrom and Redbo, 2000). Cows evolved to consume coarse fibre, grass or browse, and feeding a high-energy, high-protein diet with limited fibre to make them yield more milk can easily lead to digestive disorders, such as acidosis, and behavioural problems. These are evident in the form of tonguing behaviour, in which the tongue is extended from the mouth and twisted or curled, repetitively. The total time that a cow spends chewing (feed prehension bites + feed mastication bites and rumination bites) is a good index of the adequacy of fibre intake to maintain normal rumen function (Balch, 1971). In calves, a similar stereotyped behaviour problem occurs when they are prevented from suckling their mother, especially if their milk is offered to them in buckets. This is excessive licking or sucking behaviour, of their surroundings (Fig. 2) or any body part of herdmates that

Figure 2 Calf sucking bars of its pen. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Understanding the behaviour of dairy cattle

is easily sucked, such as their ear. Later, this can develop into cows sucking each other’s udders, termed intersucking, or into prepuce sucking in males. Drinking is usually accomplished by dipping the muzzle into the water, with the nares exposed, and sucking it into the buccal cavity. However, if water troughs are inadequately earthed, there might be stray voltage that causes the cows to lap the water like a dog, providing clear evidence that immersion of the muzzle causes them discomfort. Cows are particularly sensitive to electric currents, which can also disturb them in the milking parlour. Despite this, electricity is used to contain them in the field and control access to a self-feed silage pit and entry to the parlour, in the form of an electrified backing gate.

4.3  Reproductive behaviour The social structure of matriarchal groups of cattle that existed in the wild required males to leave the herd when sexually mature, to live as bachelors in small groups or alone. A need for the bulls to detect cows in oestrus from a distance appears to have led to the emergence of a homosexual mounting behaviour in cows that is unique in mammals. In this behaviour, cows that are close to oestrus ride the backs of cows that are actually in oestrus, which lasts for about 13 h. This mounting acts as a sign to the bull that is effective over long distances. Following domestication, in village systems where bulls were often kept away from the cows, there was probably further selection for this overt display of sexual receptivity, so that bulls could be brought to the cows at the right time. Oestrous cows may be mounted as many as 130 times during their period of receptivity, but typically most of these will be missed by the herdsperson as they occur at night or in the field (Esslemont et al., 1985). The emerging intensive dairy systems with large groups of cows (Fig. 3), often several thousand, and few stockpeople to look for this behaviour, is leading to difficulties in detecting oestrus, which is nowadays followed not by a bull brought to the cow but by an inseminator with a straw of semen to inject into the cow. (a)

 

(b)

 

 

Figure 3 A traditional alpine housing system for small numbers of cows (a) and a modern intensive dairy production unit (b). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Understanding the behaviour of dairy cattle11

The fundamental need for cattle to mount, a behaviour that is learnt as a calf during play mounting, also leads to problems in males, which ride each other excessively when in single groups, sometimes raping each other aggressively with resulting damage to their penises.

5  Locomotion and resting With increasing demand for milk and milk products, dairy production systems are intensifying worldwide, keeping more cows in permanently housed conditions. Although tying cows in stalls in their housing has largely disappeared because of the high labour requirement, keeping large herds in free-stall housing presents significant challenges for them to be able to rest normally and walk unhindered. In addition, cows have also been genetically modified to produce more milk, leading to larger and heavier udders. As these high-yielding cows walk, they have to move their hind limbs around the udder, creating a lateral force on the outer claws, resulting in limb disorders mostly stemming from problems in these claws (Fig. 4). Cow gait scoring systems have been developed to monitor how normal a cow’s locomotion is, but about 60% of cows with an abnormal gait do not become lame (Phillips, 1990). As a result, it is difficult to use this as a preventative assessment tool. The intensively bred dairy cow has a particularly high demand for rest when she is producing large quantities of milk (Norring et al., 2016), but may be thwarted from resting for a sufficiently long period each day if the lying space is uncomfortable or if she has to spend a long time grazing to sustain a high milk yield. Cows in strawed yards can spend 50% more time lying than those in free-stall (cubicle) housing (Phillips and Schofield, 1994), because the depth of straw and freedom of movement allow for a more natural lying behaviour. During transport, cows may also be unable to lie down for long periods. Looking at whether cows feed, drink or lie down after being prevented from doing these essential behaviours is a good way of determining their priorities, even though the motivation for some, such as drinking, may be satisfied more rapidly than others. Cows’

Figure 4 A cow with severe lameness in her hind right hoof, note arching of the back to reduce load on the rear limbs. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Understanding the behaviour of dairy cattle

Figure 5 Low-quality cubicle accommodation for cows, with cows lying back to front in the cubicles and slurry on the floor, leading to coat contamination.

Figure 6 Lunging of a lying cow while rising.

behaviour in free stalls can give a clear indication of their comfort level. If they limit their movements within the stall, do not get up regularly or lie facing the passage behind the free stalls, it suggests that they are uncomfortable (Fig. 5). Free-stall design has received much attention from agricultural engineers and improvements have been made. None can overcome the basic problem of requiring cows to lie in a space little bigger than their body outline, when their natural behaviour at pasture is to lunge forward (Fig. 6) and sideways as they get up, and to leave a reasonable distance to their nearest neighbour. However, free stalls can be made more comfortable by ensuring that there is at least one stall per cow (Fregonesi et al., 2007a), that divisions and bed sizes are suitable for lying down with ease (Ceballos et al., 2004), that enough bedding, preferably of straw rather than sand (Norring, 2008), or a rubber mat (Herlin, 1997), is provided and that it is dry (Fregonesi et al., 2007b).

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Understanding the behaviour of dairy cattle13

The duration of lying is not always a good indicator of well-being in cows; for instance, lame cows often lie down for longer than cows with sound feet (Miguel-Pachero et al., 2016). Cattle need to sleep just like other mammals, but excessive sleep, including the drowsiness that cattle typically show when they are lying with their head lifted and still, can indicate a stressful situation, such as in individual housing (Babu et al., 2004) or during transport (Atkinson, 1992). Optimum lying time in free stalls is about 12 h per day (Jensen et al., 2005; Munksgaard et al., 2005).

6  Behaviour during transport and slaughter During transport there is a temptation to load as many cattle as possible onto a truck (Fig. 7), in a ship or an aeroplane, and similarly during slaughter rapid processing of cattle can hinder the careful attention to each animal that is required for good welfare. As a result, cattle are often subjected to very poor conditions that reduce their welfare during transport and slaughter. This could affect the sustainability of cattle production systems, as the public are very concerned about this aspect of the system (Tiplady et al., 2015). A knowledge of how they behave in such circumstances should help to know when to take preventative action. During cattle sales, transport and at abattoirs, the mixing of cattle

Figure 7 A heavily stocked cattle truck. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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(especially if some have horns), rough handling (including use of the electric prodder), novelty of the environment, sudden movements, lights and sounds all combine to stress cattle, particularly dairy cows (Lanier et al., 2000). Their response is to make sudden flinching or startle movements, fall over, vocalise, become aggressive, urinate and/or defecate (Maria et al., 2004; Minka and Ayo, 2007). At the slaughter plant, cattle are isolated from conspecifics for the slaughter process, as well as again facing handling that may be rough (Bourguet et al., 2010). To reduce contamination of the carcase with gut contents and to keep trucks unsoiled by excreta, cattle may be prevented from feeding for a day or more before slaughter, creating additional stress. In addition, they often arrive fatigued from a long period standing in a truck, after making regular stepping movements to maintain their balance. At times they may fall, both on the truck and getting on and off. In situations of high stocking density they may not be able to get back up again. Once in the killing box, cattle are usually stunned with either a percussive instrument, which may be ineffective due to inaccurate placement or insufficient power, or a transcranial electrical shock, which produces only a short period of insensibility of about 35 seconds. The electrical stun can be accompanied by electroimmobilisation to stop the animal from kicking. Cattle for the halal market must die from a knife cut to the throat, sometimes after being inverted to facilitate an effective cut, a procedure likely to cause severe stress. In Asian countries they may be stunned with a sledgehammer or cast to the ground with ropes, followed by the knife cut to the throat, which if ineffective leads to cattle slapping their heads on the floor. All of these procedures constitute potentially painful and stressinducing treatments of the animals, which can be reduced by following best practice. A behaviour observed following effective stunning is vibration of the eyeball, nystagmus (Gregory et al., 2007).

7 Conclusions The tools to evaluate the emotions of dairy cows are under development, but they are urgently needed to evaluate the impact of modern, intensive systems of production on the behaviour and welfare of dairy cows. Particular challenges occur with satisfying cows’ motivation for feeding, provision of adequate facilities for resting and walking, and limiting stress responses during handling, transporting and slaughtering cows. Utilising the new tools that are becoming available should enable improved systems to be devised that more effectively meet the welfare needs of dairy cows throughout their lives. Effective management of cows by well-trained stockpeople with a good relationship with their cows in systems of production that account for the major needs of cows will lead to better welfare and more sustainable production.

8  Future trends The new techniques to assess the emotions of cows through sophisticated behaviour tests will be invaluable in developing new systems of keeping cows that provide a quality of life, which the public accept as worthwhile. Currently, the emergence of intensive dairy farming systems to meet increased milk demand is attracting significant criticism from © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Understanding the behaviour of dairy cattle15

public advocacy groups (e.g. Voiceless, 2015). The concerns centre on the early separation of calves from their dams, the slaughter of large numbers of male calves, the permanent housing of cow herds and the increasingly short life of cows. Alternatives are available, but it is not clear either whether cow and calf welfare is appropriately improved or whether the ethical concerns of the public will be assuaged. Nurse cows can be used to foster calves, allowing their high-yielding dams to produce milk. Sexing semen can allow only female calves to be born, but in this case there will be surplus female rather than male calves, as only a proportion of the cows are needed to breed herd replacements. There is a strong demand for heifer calves to be exported from the major dairy producing countries to developing countries to help them build their own dairy industries, but conditions for them both during transport and in the recipient countries often lead to poor welfare. Permanent housing has been an increasingly common phenomenon to be able to control feeding, so that high milk yields are achieved, to facilitate automatic (robotic) milking and to enable land to be used to grow crops that yield more than cows can harvest from pasture. Behavioural research has indicated that cows housed at high stocking densities spend less time in natural behaviours, in particular resting, and are more likely to develop some health and reproductive problems. The paradox is that the public often mistakenly believes that cows are happily grazing at pasture. The short life of cows, often just four to five years, is largely due to the intensive nature of modern production systems, which require cows to produce increasingly large amounts of milk in an environment that is far removed from that for which they naturally evolved. India, the nation with the world’s largest dairy herd, has a tradition of providing retirement shelters for dairy cows that have passed their productive life, which is firmly embedded in the national religion, and is supported by philanthropy locally and nationally. Such provisions may become required in Western countries if higher ethical standards are adopted. There the increasingly urban population increasingly develop their attitudes towards animal welfare from their contact with companion animals, or an understanding of cattle production systems as portrayed in the media. Behaviour tests will be an important part of the ethics and welfare assessment that is needed for alternative systems that meet public approval better than current systems. The growing number of alternatives to cows’ milk that are being accepted by the public will focus attention on developing improved systems expeditiously.

9  Where to look for further information Introductions to the subject for non-specialists: •• Albright, J. L. and Arave, C. W. 1997. The Behaviour of Cattle. CAB International, Wallingford, p. 306. •• Phillips, C. J. C. 2002. Cattle Behaviour and Welfare. Blackwell’s Scientific, Oxford, p. 264. •• Moran, J. and Doyle, R. 2015. Cow Talk: Understanding Dairy Cow Behaviour to Improve their Welfare on Asian Farms. CSIRO, Clayton South, Australia, p. 256. Seminal writing which has shaped the subject •• Hafez, E. S. E. and Bouissou, M. E. 1975. The behaviour of cattle. In E. S. E. Hafez (Ed.), The Behaviour of Domestic Animals. Baillière Tindall. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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•• Broom, D. M. and Fraser, A. F. 2015. Domestic Animal Behaviour and Welfare. CAB International, Wallingford, p. 472. •• Albright, J. L. 1993. Feeding behavior of dairy cattle. Journal of Dairy Science 76, 485–98. •• Breuer, K., Hemsworth, P. H., Barnett, J. L., Matthews, L. R. and Coleman, G. J. 2000. Behavioural response to humans and the productivity of commercial dairy cows. Applied Animal Behaviour Science 66, 273–88. •• Fregonesi, J. A. and Leaver, J. D. 2001. Behaviour, performance and health indicators of welfare for dairy cows housed in strawyard or cubicle systems. Livestock Production Science 68, 205–16. •• Whay, H. R., Main, D. C. J., Green, L. E. and Webster, A. J. F. 2003. Assessment of the welfare of dairy cattle using animal-based measurements: direct observations and investigation of farm records. Veterinary Record 153, 197–202. •• von Keyserlingk, M. A. G., Rushen, J., de Passille, A. M. and Weary, D. M. 2009. The welfare of dairy cattle – Key concepts and the role of science. Journal of Dairy Science 92, 4101–11. Key societies and professional organisations •• •• •• ••

American Society of Dairy Science International Society for Applied Ethology British Society of Animal Science European Food Safety Authority’s Panel on Animal Health and Animal Welfare

Key journals and conferences •• •• •• •• •• •• •• ••

Journal of Dairy Science Applied Animal Behaviour Science Animal Welfare Journal of Applied Animal Welfare Science Animal Animal Production Science Joint Annual Meetings, American Societies of Dairy and Animal Science International Society for Applied Ethology Annual Meeting

Major international research projects •• Welfare Quality Network •• See http://www.welfarequality.net/network/45848/7/0/40 and Knierim, U. and Winckler, C. 2009. On-farm welfare assessment in cattle: validity, reliability and feasibility issues and future perspectives with special regard to the Welfare Quality approach. Animal Welfare 18, 451–8 and de Vries, M., Bokkers, E. A. M., van Schaik, G., Botreau, R., Engel, B., Dijkstra, T. and de Boer, I. J. M. 2013. Evaluating results of the Welfare Quality multicriteria evaluation model for classification of dairy cattle welfare at the herd level. Journal of Dairy Science 96, 6264–73. •• Animal Welfare Indicators (AWIN), http://www.animal-welfare-indicators.net/ site/

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Research centres for possible collaboration and to keep up with research trends •• •• •• ••

University of British Columbia’s Animal Welfare Program Dairy Research Centre, Crichton Royal Farm, Scotland’s Rural College Animal Welfare and Behaviour, University of Bristol Institut National de la Recherche Agronomique, Centres at Clermont-Ferrand-Theix and Saint-Genes-Champanelle, France •• New Zealand and Australian OIE Collaborating Centre for Animal Welfare Science and Bioethical Analysis, including the Animal Welfare Science Centre, University of Melbourne, and the Centre for Animal Welfare and Ethics, University of Queensland

10 References Atkinson, P. J. 1992. Investigation of the effects of transport and lairage on hydration state and resting behavior of calves for transport. Veterinary Record 130, 413–16. Babu, L. K., Pandey, H. N. and Sahoo, A. 2004. Effect of individual versus group rearing on ethological and physiological responses of crossbred calves. Applied Animal Behaviour Science 87 (3–4), 177–91. Balch, C. C. 1971. Proposal to use time spent chewing as an index of the textent to which diets for ruminants possessthe physical property of fibrousness characteristic of roughages. British Journal of Nutrition 26, 383–91. Bourguet, C., Deiss, V., Tannugi, C. C. and Terlouw, E. M. 2011. Behavioural and physiological reactions of cattle in a commercial abattoir: Relationships with organisational aspects of the abattoir and animal characteristics. Meat Science 88, 156–68. Ceballos, A., Sanderson, D., Rushen, J. and Weary, D. M. 2004. Improving stall design: Use of 3-D kinematics to measure space use by dairy cows when lying down. Journal of Dairy Science 87, 2042–50. Clapp, J. B., Croarkin, S., Dolphin, C. and Lyons, S. K. 2015. Heart rate variability: a biomarker of dairy calf welfare. Animal Production Science 55, 1289–94. Daros, R. R., Costa, J. H. C., von Keyserlingk, M. A. G., Hötzel, M. J. and Weary, D. M. 2014. Separation from the dam causes negative judgement bias in dairy calves. PLoS ONE 9 (5), e98429. de la Torre, M. P.. Briefer, E. F., Ochocki, B. M., McElligott, A. G. and Reader, T. 2016. Mother-offspring recognition via contact calls in cattle, Bos taurus. Animal Behaviour 114, 147–54. Esslemont, R. J., Bailie, J. H. and Cooper, M. J. 1985. Fertility Management of Dairy Cattle, Collins, London, p. 83. Fagen, R. 1981. Animal Play Behaviour, Oxford University Press, Oxford. Fregonesi, J. A., Tucker, C. B. and Weary, D. M. 2007a. Overstocking reduces lying time in dairy cows. Journal of Dairy Science, 90, 3349–54. Fregonesi, J. A., Veira, D. M., von Keyserlingk, M. A. G. and Weary, D. M. 2007b. Effects of bedding quality on lying behavior of dairy cows. Journal of Dairy Science, 90, 5468–72. Goldberger, J. J., Challapalli, S., Tung, R., Parker, M. A. and Kadish, A. H. 2001. Relationship of heart rate variability to parasympathetic effect. Circulation, 103, 1978–83. Grandin, T. 1989. Behavioral principles of livestock handling. Professional Animal Scientist, December 1989. http://www.grandin.com/references/new.corral.html (accessed 6 July 2015). Gregory, N. G., Lee, C. J. and Widdicombe, J. P. 2007. Depth of concussion in cattle shot by penetrating captive bolt. Meat Science 77, 499–503. Herlin, A. H. 1997. Comparison of lying area surfaces for dairy cows by preference, hygiene and lying down behaviour. Swedish Journal of Agricultural Research 27, 189–96.

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Hernandez, C. E., Thierfelder, T., Svennersten-Sjaunja, K., Berg, C., Orihuela, A. and Lidfors, L. 2014. Time lag between peak concentrations of plasma and salivary cortisol following a stressful procedure in dairy cattle. Acta Veterinaria Scandinavica 56, 61, doi: 10.1186/s13028-014-0061-3. Hopster, H., O-Connell, J. M. and Blokhuis, H. J. 1995. Acute effects of cow-calf separation on heartrate, plasma-cortisol and behavior in multiparous dairy cow. Applied Animal Behaviour Science 44, 1–8. Jackson, P. G. G. 1995. Handbook of Veterinary Obstetrics, W. B. Saunders, London. Jensen, M. B., Pedersen, L. J. and Munksgaard, L. 2005. The effect of reward duration on demand functions for rest in dairy heifers and lying requirements as measured by demand functions. Applied Animal Behaviour Science 90, 207–17. Lanier, J. L., Grandin, T., Green, R. D., Avery, D. and McGee, K. 2000. The relationship between reaction to sudden, intermittent movements and sounds and temperament. Journal of Animal Science 78, 1467–74. Le Neindre, P. 1989a. Influence of cattle rearing conditions and breed. 1. Relationships of mother and young. Applied Animal Behaviour Science 23, 117–27. Le Neindre, P. 1989b. Influence of rearing conditions and breed on social behaviour and activity of cattle in novel environments. Applied Animal Behaviour Science 23, 129–40. Lindstrom, T. and Redbo, I. 2000. Effect of feeding duration and rumen fill on behaviour in dairy cows. Applied Animal Behaviour Science 70, 83–97. Loberg, J. M., Hernandez, C. E., Thierfelder, T., Jensen, M. B., Berg, C. and Lidfors, L. 2008. Weaning and separation in two steps – A way to decrease stress in dairy calves suckled by foster cows. Applied Animal Behaviour Science 111, 222–34. Lomas, C. A., Piggins, D. and Phillips, C. J. C. 1998. Visual awareness. In special issue on ‘Animal Awareness, Concepts and Implications for Domesticated Animals’, D. Piggins and C. J. C. Phillips (Ed.), Applied Animal Behaviour Science 57, 247–57. Mandel, R., Whay, H. R., Nicol, C. J. and Klement, E. 2013. The effect of food location, heat load, and intrusive medical procedures on brushing activity in dairy cows. Journal of Dairy Science 96, 6506–13. Maria, G. A., Villarroel, M., Chacon, G. and Gebresenbet, G. 2004. Scoring system for evaluating the stress to cattle of commercial loading and unloading. Veterinary Record 154, 818–21. Miguel-Pacheco, G. G.,Thomas, H. J., Kaler, J., Craigon, J. and Huxley, J. N. 2016. Effects of lameness treatment for claw horn lesions on lying behaviour in dairy cows. Applied Animal Behaviour Science 179, 11–16. Minka, N. S. and Ayo, J. O. Effects of loading behaviour and road transport stress on traumatic injuries in cattle transported by road during the hot-dry season. Livestock Science 107, 91–5. Munskgaard, L., Jensen, M. B., Pedersen, L. J., Hansen, S. W. and Matthews, L. 2005. Quantifying behavioural priorities-effects of time constraints on behavior of dairy cows. Applied Animal Behaviour Science 92, 3–14. Norring, M., Manninen, E., de Passille, A. M., J., Munksgaard, L. and Saloniemi, H. 2008. Effects of sand and straw bedding on the lying behavior, cleanliness, and hoof and hock injuries of dairy cows. Journal of Dairy Science 91, 570–6. Norring, M. and Valros, A. 2016. The effect of lying motivation on cow behaviour. Applied Animal Behaviour Science 176, 1–5. Phillips, C. J. C. and Arab, T. M. 1998. The preference of individually-penned cattle to conduct certain behaviours in the light or the dark. Applied Animal Behaviour Science 58, 183–7. Phillips, C. J. C. and Leaver, J. D. 1986. The effect of forage supplementation on the behaviour of grazing dairy cows. Applied Animal Behaviour Science 16, 233–47. Phillips, C. J. C. and Lomas, C. A. 2001. The perception of color by cattle and its influence on behavior. Journal of Dairy Science 84, 801–13. Phillips, C. J. C., Oevermans, H., Syrett, K. L., Halli, K., Jespersen, A. Y. and Pearce, G. P. 2015. Lateralisation of dairy cow behaviour responses to conspecifics and novel persons. Journal of Dairy Science 98, 2389–400.

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Understanding the behaviour of dairy cattle19 Phillips, C. J. C. and Schofield, S. A. 1994. The effect of cubicle and straw yard housing on the behaviour, production and hoof health of dairy cows. Animal Welfare 3, 37–44. Phillips, C. J. C. and Weiguo, L. 1991. Brightness discrimination by cattle relative to that of humans. Applied Animal Behaviour Science 31, 25–33. Robins, A. and Phillips, C. J. C. 2010. Lateralized visual processing in domestic cattle herds responding to novel and familiar stressors. Laterality: Asymmetries of Body, Brain and Cognition 15, 514–34. Tiplady, C., Walsh, D. and Phillips, C. J. C. 2015. Ethical issues concerning the public viewing of media broadcasts of animal cruelty. Journal of Agricultural and Environmental Ethics 28, 635–45, doi: 10.1007/s10806-015-9547-x Van Vuure, C. 2005. Retracing the Aurochs. Pensoft Publishers, Sofia. Verbruggen, S. W., Loo, J. H. W. and Hayat, T. T. A 2016. Biomechanics and Modeling in Mechanobiology 15, 995–1004. Voiceless, 2015. The Life of the Dairy Cow. https://www.voiceless.org.au/our-approach/research-andpublications/the-life-of-the-dairy-cow (accessed 7 July 2016). von Borell, E., Langbein, J., Despres, G., Hansen, S., Leterrier, C., Marchant-Forde, J., MarchantForde, R., Minero, M., Mohr, E., Prunier, A., Valance, D. and I. Veissier. 2007. Heart rate variability as a measure of autonomic regulation of cardiac activity for assessing stress and welfare in farm animals. A review. Physiology and Behaviour 92, 293–316. Webster, A. J. F. 2016. Animal Welfare: Freedoms, dominions and ‘a life worth living’. Animals 6, 35, doi: 10.3390/ani6060035 Weiguo, L. and Phillips, C. J. C. 1991. The effects of supplementary light on the behaviour and performance of calves. Applied Animal Behaviour Science 30, 27–34.

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Chapter 2 Key issues in the welfare of dairy cattle Jan Hultgren, Swedish University of Agricultural Sciences, Sweden 1 Introduction: an overview of interest in and determinants of animal welfare in dairy farming 2 Husbandry practices in dairy farming: housing, handling and farming procedures 3 Husbandry practices in dairy farming: health, productivity and breeding 4 Applying different perspectives on animal welfare to the case of dairy farming 5 Recommendations for improving animal welfare in dairy farming in the light of expected future developments 6 Summary 7 Where to look for further information 8 Acknowledgements 9 References

1 Introduction: an overview of interest in and determinants of animal welfare in dairy farming 1.1  Interest in animal welfare in dairy farming Concern about the welfare of dairy cattle is widespread. It is based on beliefs that animal well-being matters and that humans have responsibilities towards the animals in their care. This has always been recognized by people committed to the care of dairy cattle, inspiring management practices, education, publications, campaigns, guidelines and legislation throughout the history of milk farming. The more recent scientific interest in animal welfare stems largely from a public concern about modern methods and techniques in farm animal husbandry, including farming for milk. With industrialization and rationalization efforts during the last century, including changes in infrastructure, feed imports, innovations in animal genetics, breeding and mechanization of work, production systems have become more confined, and dairy farms more sparsely scattered and larger. Relating the number of dairy holdings in a country to the number of inhabitants may highlight this trend (Fig. 1). The average herd size is today well above a hundred cows in a number of countries (Anon., 2013c; Fig. 2). Farms with several tens of thousands of cows are seen in the United States, Saudi Arabia and China, and mega dairies of 100 000 cows will soon become a reality. http://dx.doi.org/10.19103/AS.2016.0006.02 © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Key issues in the welfare of dairy cattle

Dairy operations per 106 inhabitants

14,000 China Denmark Italy Japan New Zealand United Kingdom United States

12,000 10,000 8,000 6,000 4,000 2,000 0 1975

1980

1985

1990

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Figure 1 Selected national statistics of the number of dairy holdings per million inhabitants 1975–2014 (Anon., 2010c, 2013a,b,c, 2015a,b, 2016e,g,h,i,k). Data from different countries may not be directly comparable. 500

Mean cow herd size

400

300

China Denmark Italy Japan New Zealand United Kingdom United States

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0 1975

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Figure 2 Selected national statistics of mean dairy herd size 1975–2014 (Anon., 2010c, 2013a,b,c, 2015a,b, 2016e,g,h,i,k). Data from different countries may not be directly comparable.

At the beginning of the 1900s, European and North American dairy cows were generally tethered in tie-stalls when kept indoors in wintertime (Bickert, 2003), but loose housing with cubicles (free-stalls) is today the predominant way of keeping cows in large dairy operations. Nonetheless, tie-stalls are still fairly common, especially in smaller herds. In Europe and North America, dairy cows are often kept indoors permanently or kept on © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle23

outdoor dry lots with little or no access to pasture, and this is the so-called zero-grazing. In New Zealand, Australia, Ireland and South America, on the other hand, intensive dairy cattle systems involve grasslands and pastures. During a half-century of structural and technological innovation, milk yields have more than doubled (Anon., 2016f,i). Milk production has thus intensified in three different ways; more confined systems, fewer units and higher yields. Arguably, the profitability of milk farming enterprises and a quest for efficiency have been the main drivers for intensification. This trend continues today. Parallel to the intensification of milk production, urbanization has seen rapid growth, which has created a human population with limited experience of farm animals. For the first time in modern history, large groups of people seem ignorant of food animal production and lack basic understanding of the terms of intensive milk farming. Nonetheless, the concern for farm animal welfare has increased and now seems to be greater than ever. Many citizens demand to be assured that food animals have a decent life and be killed in a humane way when their productive life is over. Globally, about three-quarters of all dairy operations are household farms with 1–3 cows and these households sell milk for cash or consume it to fulfil daily needs (Anon., 2010c). Nevertheless, because of the challenges that the intensification of milk production has brought about, this chapter looks into key issues in the welfare of specialized dairy cattle on family farms or corporate dairies in intensive production, together producing most of the milk in the world, albeit representing a minority of the global cow population.

1.2  Determinants of animal welfare Several factors determine the welfare of dairy cattle. Some of these relate to the environment that surrounds dairy farms and animals, such as climatic conditions, pasture vegetation and wildlife. Others follow from contacts with conspecifics on farm. Some major challenges to animal well-being are even inherent to life itself and therefore cannot be avoided altogether. In many ways, however, animal welfare is a consequence of the husbandry conditions. Housing and handling have a major impact through confinement and other limiting conditions for the animals, but also by protecting them from harmful influences of other animals or the environment, which arguably puts a great responsibility on the stockperson or animal caretaker. Many of the determinants of the welfare of dairy cattle are dealt with in other texts, as well as the remaining chapters of this volume. This section highlights some of the most important issues. Due to the complex nature of animal welfare, its determinants are entangled in a multidimensional web of mutual dependencies (Anon., 2012c). Heritage and previous experiences will determine the basic conditions, that is, physical capacities, ability to contentment, and susceptibility to external influences. The animal may be exposed to a risk factor for poor welfare for a very short time period, which may have a decisive, adverse or favourable impact for the rest of its life. For example, trauma may cause permanent injury, and forced premature separation from the mother can cause long-term behavioural changes and possibly mental suffering to a calf (Stěhulová et al., 2008; Gaillard et al., 2014). Conversely, good treatment early in life can have favourable effects on animal welfare much later. For example, animals reared together from birth show less aggressive interactions towards each other even after one year of being grouped with other animals and are more tolerant in competitive situations compared to animals reared separately (Bouissou and Andrieu, 1978). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Moreover, welfare determinants often interact by moderating (strengthening or weakening) each other's effects. For example, an animal heavily contaminated with manure can be more sensitive to low temperatures (Anon., 2009d), and stress from high production or social submissiveness can increase its susceptibility to infectious disease (Ingvartsen et al., 2003; Proudfoot et al., 2012). Finally, different aspects of bad (or good) animal welfare can arise in several ways by exposure to what appears to be a single determinant, sometimes as an indirect effect long after exposure to the determinant. For example, a faulty stall design restricts the animals’ movements more than necessary, which can make the stall floor and animals dirty, which in turn will increase the risk of mastitis and hoof disease, which will ultimately increase the likelihood of culling at the end of lactation. In this case, the faulty stall design may be regarded as the primary determinant in a long chain of events. Along the chain, poor animal welfare results from, for example, restricted movements (abnormal behaviour, frustration, injury), contamination with manure (discomfort, pain, skin disease, reduced function), udder infection (pain, malaise, reduced function), hoof infection (pain, lameness, reduced function) and culling (reduced lifetime). In this way, cause and effect are inextricably linked and become practically indistinguishable. It is not even obvious what the primary welfare determinant is (Fig. 3). If the severity of poor welfare is plotted against time, an overall estimate of welfare is the area under the curve thus produced (Broom, 2001). An example of this is given in Fig. 4. In connection with dehorning of calves, the absence of analgesic treatment results in a negative welfare response, as indicated by elevated blood cortisol concentrations during ten hours following treatment. A local anaesthetic improves total welfare (smaller area under curve) but postpones the negative response, resulting in high cortisol levels Reduced lifetime Reduced biological function Impaired locomotion Abnormal behaviour Pain Discomfort Malaise Hoof infection Udder infection Eczema Contamination of floor and animal Restricted movements Faulty stall design

Figure 3 Example of plausible relationships between different determinants and manifestations of animal welfare, represented by boxes and related to feelings (e.g. discomfort, pain), biological function (e.g. udder infection, impaired locomotion) or natural life (e.g. behaviour, lifetime). Time goes from left to right, box width indicates duration and the arrows represent alleged causal links. Most of the determinants are also manifestations, and vice versa. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle25 100

Concentration (nmol/l)

No analgesia Local anaesthetic

80

Local anaesthetic + NSAID

60 40 20 0

0

2

4 6 Time after treatment (hours)

8

10

Figure 4 Example of changes in calf welfare, as indicated by cortisol concentration in blood, in response to dehorning of calves with no analgesia, a local anaesthetic and a local anaesthetic combined with a nonsteroidal anti-inflammatory drug (modified from Stafford and Mellor, 2005).

six to nine hours after treatment. The combination of a local anaesthetic and an antiinflammatory drug appears most favourable (smallest area under curve).

2 Husbandry practices in dairy farming: housing, handling and farming procedures 2.1  Confinement and restricted movement Tie-stalls restrict the freedom of movement and tied animals are almost completely deprived of exercise. Depending on the type of tie-stalls, they are also partly prevented from performing self-grooming. Furthermore, subdominant individuals are unable to move away from dominant neighbours. On the other hand, cows in tie-stalls do not have to compete as much for resources like feed, water and a lying place, compared to loosehoused cows, and it may be easier to give them individual care. Cows are motivated to walk and tethering thwarts this motivation, although the animals not necessarily show a physiological stress response (Veissier et al., 2008). According to the European Food Safety Authority (EFSA) (Anon., 2009d), tie-stall housing compromises the welfare of dairy cattle, comparing with open, bedded packs. However, EFSA did not consider free-stall housing associated with an increased incidence of leg and locomotor disorders as favourable as tie-stalls. Popescu et al. (2013, 2014) found that loose housing (in cubicles or a straw yard) in Romania have welfare advantages compared to tie-stalls, but they also concluded that welfare is not necessarily poorer in tie-stall housing. Lower incidences of a number of diseases have been found in cubicles than in tie-stalls in Norway, although this difference was not so clear for small free-stall operation (Simensen et al., 2010). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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At pasture, cows can move freely on a relatively clean and dry surface, and a large number of studies indicate that seasonal pasture is beneficial to cow health. For example, pasture access is associated with a lowered risk for leg and foot lesions, and lameness (Haskell et al., 2006; Hernandez-Mendo, 2007; Rutherford et al., 2008; Bergman et al., 2014). Barkema et al. (1999) and Washburn et al. (2002) found a reduced incidence of mastitis in herds with access to pasture. According to EFSA (Anon., 2009d), access to pasture reduces the risk for hoof diseases, lameness, teat tramping, mastitis, acute metritis, dystocia, ketosis, retained placenta and various bacterial infections. Danish and Swedish studies have also shown a reduced mortality risk in herds with more pasture access (Thomsen et al., 2007; Burow et al., 2011; Alvåsen et al., 2014). There is evidence that cattle prefer access to pasture, but this preference depends on the time of day and the weather conditions; cattle avoid bright sunshine and high temperatures (Legrand et al., 2009; Charlton et al., 2013). In some regions, especially densely populated areas where cultivated land is scarce, or where regulations on ammonia emission or nutrient leakage are placed on livestock farmers that limit their use of pastures, cows are kept indoors all-year round, and this is so-called zero-grazing. Astrid Lindgren, the famous Swedish author of children’s stories, argued for the right of cattle to have outdoor access during summer, and she exercised some influence on the Swedish animal welfare legislation issued in 1988 in this regard. The practice of zero-grazing tends to increase, although reliable information is scarce. EFSA (Anon., 2009d) recognized zero-grazing as a major animal welfare issue, although it received a low risk score while being estimated as a relatively uncommon practice in Europe.

2.2  Disruption of social structures Cattle fall under the category of social animals. As pointed out by EFSA, the social environment in early life and the management of grouping during rearing may have long-term effects on animal welfare, but has commonly not received attention in practice (Anon., 2009d). Groups of cattle develop a social hierarchy which determines priority of access to resources. Fraser and Broom (1990) estimated the number of cattle that can be recognized and remembered by an individual to 50–70, a group size frequently exceeded in large dairies. Although research on this topic is scarce, mixing of animals and very large groups disrupt the social structures, thus inducing the possibility of aggression; however, the level of aggression and stress during the introduction of unfamiliar animals into a herd seems to depend on specific management practices or particular circumstances (Menke et al., 1999). Frequent regrouping of livestock may also increase exposure to pathogens and prolong disease outbreaks. Social isolation causes severe stress in heifers and the mere sight of conspecifics reduces behavioural distress (Boissy and Le Neindre, 1997). Most dairy calves are separated from their mothers at an early age, often immediately after birth, to be reared individually, in pairs or in larger groups. The welfare consequences of this practice have been subject to a considerable amount of research (Flower and Weary, 2003; Johnsen et al., 2016). Independently of nursing, calf and dam form bonds (Johnsen et al., 2015). Consequently, both react behaviourally to separation. The response is more intense and lasts longer when separation is delayed until four or seven days postpartum, compared to one day (Stěhulová et al., 2008), and this effect is prolonged and further intensified when the animals have visual and auditory contact after separation. On the © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle27

other hand, delayed separation influences the later social behaviour of calves in a way that may enhance their coping abilities (Bouissou et al., 2001). Johnsen et al. (2015a) found calves, separated from their mothers after eight weeks of suckling, to display less alert behaviour and high-pitch vocalizations if they were separated with a fence allowing physical contact, compared with a solid wall allowing merely auditory contact. Maternal rearing during four days and group housing, as compared to rearing without dam and individual housing, respectively, independently increase growth and play behaviour in dairy calves (Valníčková et al., 2015). Group housing has also been shown to improve cognitive performance (Gaillard et al., 2014). Group pens equipped with automated milk feeding systems are commonly used for heifer calves to reduce labour and enable delivery of milk at volumes and frequencies that are more natural and support fast growth (Fig. 5). Additionally, the automated calf feeder gives each calf more space, allows social interaction between calves and generates data on individual milk intake which can be used to monitor calf health (Borderas et al., 2009). However, the system can increase the risk of clinical respiratory-tract disease and even reduce growth rate (Svensson et al., 2003, 2006). Stable groups of no more than eight calves seem preferable from an animal health perspective (Svensson and Liberg, 2006; Engelbrecht Pedersen et al., 2009). As pointed out by Barkema et al. (2015), it may be difficult to achieve small and stable calf groups in practice, especially at small farms. Further research on the management of this rearing system is, therefore, needed. Vasseur et al. (2010a) studied calf management practices and welfare in Canada and identified the following factors as causing major risks: no access to a calving pen and poor surveillance of calvings, especially at night; no disinfection of newborn’s navel and delayed identification and monitoring of calf; unreliable feeding of colostrum of unknown quality; dehorning and removal of supernumerary teats at a high age and without adequate pain management; restrictive milk feeding and feeding with waste milk without precaution; abrupt weaning and inappropriate housing (i.e. in crate, tied or attached against a wall).

Figure 5 Calves are typically separated from their mothers shortly after birth, and from one week of age reared in groups with automatic milk feeders (Photo: J. Svennås-Gillner, Swedish University of Agricultural Sciences). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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2.3  Painful and frightening procedures Pain, fear and distress are obvious welfare issues in dairy cattle, although their relative importance is contentious. A number of surgical mutilations are performed routinely in dairy calves. Castration and disbudding cause pain and subsequent stress to calves (Anon., 2014a). It is now clear that a combination of sedation, a local anaesthetic and a nonsteroidal anti-inflammatory drug is needed to reduce the pain during these procedures and afterwards (Fig. 4; Stafford and Mellor, 2005; Stock et al., 2013; Anon., 2014a). It is less well known how age influences the effect of pain on welfare. Mutilations usually require animals to be restrained, which in itself may cause distress, in addition to the pain from surgery. Less force is needed to restrain a small animal, which may imply a lower stress response at young age. The tissue damage will also be more limited in young animals, possibly resulting in less pain. On the other hand, because of the immaturity of the nociceptive system, young animals might be more sensitive to pain (Loizzo et al., 2009). For necessary mutilations, research is needed to find the optimal age. Castration of male dairy calves destined for meat production is one of the most common management practices performed in intensive milk production. It is usually achieved by surgical removal or physical damage to the testicles. In most countries male dairy calves are castrated to facilitate handling during rearing for meat production. The extent to which analgesic treatment is applied varies greatly. It is generally recommended that intensively kept loose-housed adult dairy cattle be dehorned to prevent injuries in animals and staff and facilitate animal handling. Heifer calves are usually disbudded at the age of 4–8 weeks, when horn buds are 5–10 mm long, using a heated disbudding iron or caustic paste. In a survey in 2007, the US Department of Agriculture reported 94% of the dairy operations to routinely dehorn their heifer calves and 18% to use analgesics (Anon., 2009b). According to a European survey in 2009, 82% of the dairy cattle in Europe were dehorned, most commonly by disbudding, and only 20% of the herds used analgesics, with considerable variation between countries (Anon., 2009a). Optionally, there are some prospects for genetic selection for polledness (Medugorac et al., 2012). Another common practice is to remove supernumerary teats in replacement heifers. Such extra teats can affect normal milking and may get infected, thus contributing to reduced welfare (Anon., 2009d). The United States Department of Agriculture (USDA) reported 50% of surveyed dairy operations in the United States in 2007 to remove extra teats routinely, usually during the first six months of life (Anon., 2009b). The animal welfare implications of this procedure are largely unknown. Tail docking of cows was initially introduced to reduce the incidence of leptospirosis in milking personnel in New Zealand (Anon., 2014b), a causal link which was later refuted. According to the previously mentioned USDA survey, 39% of the cows at dairy operation in the United States were tail docked in 2007, which was most commonly achieved by applying a band around the tail (Anon., 2009b). Research has shown that tail docking provides no advantages to the cows in terms of cleanliness or udder health (Sutherland and Tucker, 2011). Instead, it causes acute and chronic pain, as well as a reduced ability to use the tail, for example, to chase insects and in social signalling. Tail docking is banned or discouraged in most industrialized countries except the United States. EFSA has recognized tail docking as an important animal welfare issue (Anon., 2009d). Since a couple of decades it has become an increasingly common practice in some regions to provide the newborn calf with the necessary colostrum through an oesophageal © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle29

tube feeder. While a sufficient provision of high-quality colostrum is essential for calf health, the routine use of an oesophageal tube is questionable. Tube feeding requires restraint, and inappropriate handling of the feeder can cause severe injury to the animal.

2.4  Transport and slaughter Animals of beef breeds constitute the main part of cattle slaughtered for meat production, and much focus is, therefore, on the transport and slaughter of these animals. However, sooner or later, most dairy cattle are also slaughtered. During loading, transport, unloading and while waiting to be slaughtered, the animals are subjected to multifarious challenges, including increased and rough handling, various unfamiliar sensations, loading onto and unloading from truck, uncomfortable lairage, deprivation of feed and water, poor climatic conditions and demanding social interactions due to separation, mixing of unfamiliar animals and crowding (Terlouw et al., 2008). The World Organisation for Animal Health (OIE) (Anon., 2016j) has recognized the significance of transport conditions for animal welfare. Major welfare issues in slaughter are inappropriate handling facilities, rough handling and insufficient or non-existent stunning (Grandin, 2013). Research has shown that animal protection standards at commercial slaughter varies considerably and is sometimes unacceptably low (von Wenzlawowicz et al., 2012; Atkinson et al., 2013). Driving, restraint and stunning procedures are not always performed correctly, and operator competence is crucial. Old and inappropriate facilities for driving and handling the animals are common, leading to unnecessary rough human–animal interactions and stress in both abattoir personnel and cattle. In some abattoirs, electric prods are used extensively. Hemsworth et al. (2011) and Hultgren et al. (2014) found cattle stress reactions to be associated with rough handling at the abattoir. Atkinson et al. (2013) evaluated stun quality following stunning with a cartridge-driven penetrating captive bolt gun, and found signs of consciousness indicative of inadequate stun in 6.5% of the cows, steers and calves, and in 17% of the bulls. A particularly controversial issue is slaughter without previous stunning for religious purposes. Stunning is performed to induce immediate unconsciousness, in that way ensuring slaughter without causing the animals any avoidable pain or distress. Stunning before slaughter is a statutory requirement in the European Union (Council Regulation [EC] 1099/2009), but exemptions from stunning are granted for religious groups. However, pre-slaughter stunning is accepted by some Islamic authorities, and in a few countries like Sweden, Denmark, Norway, Iceland, Switzerland, Liechtenstein and New Zealand, religious slaughter is allowed only after proper stunning. Gregory et al. (2012) estimated that 10% or more cattle develop complications during bleeding at halal and shechita slaughter without stunning, taking longer to lose consciousness due to false aneurysms which develop in the arteries and stop the blood flow from the severed vessels, and continued blood flow to the brain through collateral routes. The time from cutting to final collapse exceeded 4 minutes in 1.5% of studied animals (Gregory et al., 2012). In connection with slaughter without prior stunning, cattle are frequently heavily restrained and sometimes turned on their side or back in order to expose the throat to the operator, thus inducing additional stress (Velarde et al., 2014). EFSA (Anon., 2004) concluded that there are serious welfare concerns with slaughter without stunning, and recommended that all slaughtered animals be adequately stunned in a humane way. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Key issues in the welfare of dairy cattle

In Europe, halal meat (following Muslim practice) is produced in much greater quantities than kosher meat (Jewish shechita slaughter). According to a survey among authorities and slaughter plants in different countries, the percentage of cattle (beef and milk breeds) slaughtered as halal was between 4.5 and 20% in Germany, Italy, Spain, Australia and Israel (Velarde et al., 2010). In Israel, 84% were slaughtered according to shechita, while these animals constituted less than 1% in the remaining countries studied. In Belgium, France, Italy, Israel and Turkey, most or all slaughter plants performed halal slaughter without stunning, while German, UK and Australia abattoirs in most cases applied stunning before sticking. Production volumes of halal and kosher meat indicate that a large part is sold to the general public without being labelled as such. In some countries, there is a market for cull cows for the purpose of fattening and meat production. Animals in a very poor condition may change hands repeatedly and spend considerable time in provisional facilities waiting to be sold and reloaded, which causes unnecessary stress and suffering.

2.5  Poor stockmanship Humans inevitably play an important role in the life of dairy cattle, through both the control they exert over the animal environment and their physical presence (Waiblinger et al., 2006). Pre-industrialization literature giving advice on animal husbandry often emphasized the importance of gentle handling. A good relationship between cattle and humans reduces stress to routine management practices (Lensink et al., 2001; Waiblinger et al., 2004). Lürzel et al. (2015) found that gentle interaction was effective in reducing the calves’ fear of humans. A negative human–animal relationship, indicative of fear and avoidance of humans, increases the risk for lameness (Chesterton et al., 1989; Rouha-Mülleder et al., 2009). However, in intensive dairy farming, close positive contact between farmer and animals is not always possible. Thus, human–animal relationships show a wide variation, from what can be termed close friendship (at least for the human’s part), to a distanced approached focused on production efficiency and economic returns. Whether the welfare of dairy cattle gets better or worse when herd sizes increase is somewhat controversial. Herd size is closely linked to a multitude of other environmental and management factors, such as housing system, feeding, milking and personnel, which makes it a difficult research task to distinguish the effect of herd size itself. It seems plausible that the level of animal care is lower in very small and very large units, because the stockperson has either too little specific competence or too little time for each animal (Waiblinger and Menke, 1999). The authors found some correlation between herd size and the human–cow relationship, but the personality and attitudes of the stockperson were more important determinants of good human–animal relationship. There is some evidence that calf mortality tends to increase with increasing herd size (Gulliksen et al., 2009). In large herds, there are often several milkers and personnel changes occur more often (Menke et al., 1999). Human–animal interaction is common in connection with traditional milking, but in automatic milking systems this way of contact is largely broken. Due to low personal stakes and a lack of commitment, employees at corporate dairies may go about their work less carefully than family-farm managers (Uetake, 2013). On the other hand, large dairies may be able to invest in facilities and technologies for animal monitoring (Svensson and Jensen, 2007; Borderas et al., 2009; Rutten et al., 2013; Chanvallon et al., © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle31

2014), education of staff (Schuenemann et al., 2013), advisory tools (Vasseur et al., 2010b) and special herd health services. Dairy cattle can to some extent recognize humans and respond negatively to the presence of aversive handlers during milking, resulting in behavioural reactions and reduced milk yield (reviewed by Rushen et al., 1999). Appropriate strategies to recruit and train stockpeople are important in safeguarding the welfare of dairy cattle, because the behaviour of handlers can have large motivational and emotional effects on the animals (Hemsworth, 2009). Hemsworth (2003) suggested that cognitive-behavioural training programmes for stockpeople be introduced in the livestock sector.

3 Husbandry practices in dairy farming: health, productivity and breeding 3.1  High milk yield

Maximum attainable level of welfare

Animal welfare is sometimes portrayed (by industry spokesmen) as a prerequisite for high milk yields, or (by animal welfare advocates) as being in conflict with animal production. Neither is completely true. In general, welfare can be expected to increase with productivity up to a maximum, and to successively drop with a further increase in productivity beyond this point (McInerney, 2002; Edwards, 2008), as roughly illustrated by Fig. 6, although the details of this relationship are likely to depend on the chosen welfare definition. Genetic selection has contributed significantly to increased milk yields. It has been estimated that about half of the increase in yield during recent decades is attributable to

B

A

C D Productivity

Figure 6 Theoretical model of the conflict of interest between animal welfare and productivity (solid line). A given position on the curve represents a trade-off between maximum attainable welfare and productivity. Without producing, the animal can reach a certain level of welfare (A) If productivity increases, maximum attainable welfare improves up to a certain point (B). With further increase of productivity, welfare drops down to an unacceptable level (C) until the animal finally dies (D) Genetic progress or changes in husbandry can alter the model, resulting in improved (dashed line) or deteriorated (dotted line) welfare and/or productivity (modified from McInerney, 2002; Edwards, 2008). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Key issues in the welfare of dairy cattle

genetic progress, and the rest comes from improved management and feeding (Pryce and Veerkamp, 2001; VanRaden, 2004). Animals in a population that have been selected for high productivity appear to run a higher risk of behavioural, physiological and immunological problems, leading to impaired animal welfare (Rauw et al., 1998; Anon., 2009c). In high-producing cows, metabolic stress resulting from excessive tissue mobilization in early lactation (Bauman and Currie, 1980; Oltenacu and Broom, 2010) is thought to contribute to poor welfare. High-producing cows need to spend more time eating and might have less time available for other activities, such as resting. It is likely that such cows are more dependent on good management and feeding, including grain-based diets which may, in turn, be negative for cow welfare. Finally, continued increase in production may be perceived by the public as unethical and undermine consumer trust, on which the dairy industry relies. In the United States and a number of other countries, recombinant (artificial) bovine somatotrophin is used to enhance milk production in dairy cows. Research has shown that this treatment results in a 25% increase in the risk of clinical mastitis, a 40% reduction in conception rate and 55% increased risk of clinical lameness (Dohoo et al., 2003). The use of recombinant bovine somatotrophin in dairy cattle is not allowed in Canada, Australia, New Zealand, Japan, Israel and the European Union. Culling is the departure of cows from the herd due to sale, slaughter or death. On an average, intensively fed high-producing cows are not retained in the herd for very long and many are culled before the end of their first lactation. It is not uncommon that 38–40% of all cows calving in a herd are heifers that substitute older cows being culled. Overall, the most common reasons for voluntary culling are reproductive failure, mastitis and low production (Bascom and Young, 1998; Ahlman et al., 2011). An overall high culling rate suggests that the animals have been pushed beyond what is biologically sustainable into a state that is opposed to good welfare (Mellor et al., 2009), and a decreased length of productive life of dairy cows due to involuntary culling because of reproductive failure, illness, injury or death is a major animal welfare and ethical issue.

3.2  Breeding goals and reproductive management practices Increased milk production, which has been the main aim of breeding of dairy cattle for the last half a century, and systematic genetic selection for a high yield, generally practised since the 1990s, have led to problems for several reasons. Increased yields have resulted in declining reproduction and longevity (Rodríguez-Martínez et al., 2008; Oltenacu and Broom, 2010). There is substantial unfavourable genetic correlation of milk yield with fertility (Veerkamp et al., 2003), indicating that further one-sided selection will aggravate this problem. In order to cope with declining fertility and rationalization, dairy farmers apply intensive reproductive management of the cows. Most cows are either inseminated at spontaneous oestrus or inseminated after bi-weekly injections of prostaglandin, in both cases requiring the stockman to detect cows in oestrus. Additionally, so-called timed artificial insemination is used to eliminate oestrus detection. The standard protocol involves repeated injections of gonadotropin-releasing hormone and prostaglandin followed by insemination after ten days (Bisinotto et al., 2014). However, pregnancy rates are often low, which requires complementary oestrus detection. Detection aids like tail paint, pressure devices or pedometers are common but require additional management and attention. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle33

According to a survey conducted in the United States in 2007, 55% of the dairy operations inseminated most of their cows to spontaneous oestrus at first service (57% for heifers), and 22% used some kind of hormonal oestrus synchronization of most cows (7% for heifers), while 22% (for cows) and 33% (for heifers) used natural service by a bull (Anon., 2009b). In later services, synchronization was more common, and more than one-half of the operations used protocols for AI synchronization for at least some cows during one year. Oestrous synchronization is also common in New Zealand (Burke and Verkerk, 2010). Intensive reproductive management has ethical implications, and hormonal residues may pose a risk to consumers of animal products. The European Union does not allow the use of drugs with oestrogenic or gestagenic action for reproductive management in dairy cattle. An additional consequence of genetic selection for milk production is a decreased economic value of bull calves of dairy breed. Sexed semen can be used to reduce the number of unwanted dairy bull calves. Based on epidemiological data on clinical diseases, reproductive performance and culling in Swedish primiparous cows, presented by Oltenacu et al. (1990), Anon. (2012a) calculated the combined animal welfare effect of sexed semen, and concluded that it improves the welfare of the cows. The major benefit (76%) is associated with elimination of unwanted male calves, and additional benefits come from a lower frequency of diseases. Sexed semen might be perceived as unethical by the public.

3.3 Diseases Prevention and control of health disorders are widely recognized as fundamental to animal welfare. Such practices can contribute to animal welfare by a combination of hygiene, vaccination and anti-parasite treatments; by biosecurity measures to prevent the entry of specific pathogens into farms; by management routines to limit spread of disease within farms and by eradication programmes to eliminate certain diseases within countries or other regions (Fraser et al., 2013). Most researchers regard leg and hoof disorders, udder disease and metabolic disorders as major animal welfare issues (Anon., 2009d). Leg and hoof diseases are common and often painful, causing lameness of a prolonged course (Fig. 7). It is not uncommon that hoof lesions remain undetected, and thus untreated (Van Nuffel et al., 2015). Likewise, clinical and acute mastitis is common and often painful, although the clinical phase is more likely to be of short duration (Medrano-Galarza et al., 2012). Painful conditions can, if not dealt with properly, lead to severe undernutrition. A number of scientific studies have shown that both mastitis resistance and the clinical manifestation of ketosis, ovarian cyst, mastitis and lameness are genetically correlated with high milk yields (reviewed by Ingvartsen et al., 2003), indicating that continued selection for higher milk yield will increase the incidence of these diseases. The incidence of production-related diseases has increased greatly over the last decades. For example, Clarkson et al. (1996) estimated the prevalence of lameness in Welsh dairy herds to be 21%, while more recent prevalence estimates were 37% in English and Welsh herds (Barker et al., 2010) and 39% in zero-grazing UK herds (Haskell et al., 2006). New threats emerge from vectors spreading to previously unaffected regions due to climatic changes, such as biting midges (Culicoides spp.) that propagate the bluetongue and Schmallenberg viruses (Beer et al., 2013; Zuliani et al., 2015). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Key issues in the welfare of dairy cattle

Figure 7 Hoof disorders are extremely common in dairy cows and cause pain and impaired locomotion. They are multifactorial diseases caused by poor housing, management and feeding, as well as specific pathogens. Unilateral genetic selection for high milk yields increases cow susceptibility (Photo: C. Bergsten, Swedish University of Agricultural Sciences).

Antimicrobial resistance is a rapidly growing public and animal health threat of broad concern (Anon., 2016a,b,c). Although the causes of antimicrobial resistance are complex, liberal use of antibiotics contributes by being a main driver of selection pressure (Grave et al., 2012; Laxminarayan et al., 2013). Most of the antibiotics manufactured goes to agriculture, horticulture and veterinary medicine (Laxminarayan et al., 2013). The use of antibiotic growth promoters is banned in the European Union.

4 Applying different perspectives on animal welfare to the case of dairy farming 4.1  Increasing awareness of animal welfare issues After the Second World War, some people began to worry about the consequences of the intensification of milk production. Early public concerns about how animals were raised and treated were articulated by ethicists and social critics, such as the British animal welfare advocate and author Ruth Harrison in her seminal work Animal Machines (Harrison, 1964). It alerted the public to the fact that the industry regarded farm animals merely as production objects. Harrison described the continuous effort to obtain ever-greater production profits at whatever cost to the animals. The book had a profound impact on public opinion and agriculture, not only in the United Kingdom. It revealed farm practices such as castration and de-horning without analgesia, and feed antibiotics to people who were largely ignorant of such practices. Other animal welfare advocates, ethicists and philosophers were to follow.

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Key issues in the welfare of dairy cattle35

In a wider perspective, the changes in agriculture and milk farming seen in the last century have had both positive and negative effects on animal welfare (Fraser, 2001; Mellor et al., 2009). Nonetheless, despite obvious progress in production efficiency, the overall positive effects of intensive milk production on animal welfare are rightly questioned. Our ideas of what is best for the animals are affected by what we know – or rather think we know – about their minds and needs, and by respect for the animals. Keeping animals under conditions that appear unnatural, in which they cannot perform many of their innate behaviours or fulfil their basic biological needs, raises valid concerns about how to understand animal welfare. For cattle, natural life is generally thought to involve grazing on range land, with natural mating and young calves suckling from their mothers. This contrasts with the conditions under which dairy cattle are usually managed in intensive production systems, which many informed citizens find deeply unsatisfactory. Although there is broad consensus that farm animals are sentient beings and that good treatment and care are important for keeping them healthy and in good shape, there are diverging views on the minimum acceptable level of welfare, that is, what level ought to be provided. This question does not lend itself easily to objective assessments and judgements, because it has to do both with the definition of animal welfare we choose to adopt and how different values should be weighed against each other (Tannenbaum, 1991; Fraser, 2008a; Appleby et al., 2014). Most scientists agree that animal welfare should be defined in terms of biological functioning (e.g. health), emotional state and natural living (Fraser, 1999, 2008a). However, priority between these three aspects varies quite a bit. Moreover, despite considerable research efforts, there is a great deal of uncertainty regarding the effects of certain husbandry conditions and practices on animal welfare. In the quest for valid principles and a standard procedure for assessing animal welfare, many attempts have been made to design assessment protocols, for dairy cattle as well as other animals. Through a massive scientific effort, the Welfare Quality® project (Blokhuis et al., 2013) developed and tested a system for providing a standard way of converting science-based welfare measures into relevant consumer information. After extensive discussion with consumers, representatives of key stakeholder groups, policymakers and scientists, it was decided to base the system on the four main principles ‘good feeding’, ‘good housing’, ‘good health’ and ‘appropriate behaviour’ (Blokhuis et al., 2008). Within these principles 12 distinct and complementary welfare criteria were highlighted. Finally, measures useful for the assessment of the principles in practice were identified, designed and tested, resulting in assessment protocols for different species, including cattle (Anon., 2009e). Notable was the focus on welfare measures taken on animals, the so-called ‘animal-based measures’ or ‘output measures’. Since published, the Welfare Quality® principles, criteria and protocols have almost become regarded as the ‘truth’ of animal welfare. This is presumably due to the pressing need for valid welfare assessment standards and great confidence in the scientific approach chosen by the project. However, for reasons related to education, time constraints and data analysis, the complete protocols have proven difficult to apply on a large scale in practice. Further research is needed to develop less comprehensive but sufficiently accurate protocols. Several initiatives have been taken in this direction (Bracke et al., 1999; Andreasen et al., 2014). As an alternative approach, several systems have been designed for measuring the welfare of dairy cattle exclusively at herd level. However, such systems would not be strictly in line with the intentions of legislation that sets minimum acceptable conditions for every individual animal (Lundmark et al., 2015).

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Key issues in the welfare of dairy cattle

4.2  Naturalness and the positivist heritage Because the idea of natural behaviour has proved appealing, also in animal welfare legislation, researchers have attempted to grasp and accommodate it conceptually (Thorpe, 1965; Bracke and Hopster, 2006; Lund, 2006). The notion of something essentially important for an animal of a given species – at its present level of domestication and breeding – may be relevant. Unfortunately, it is somewhat troublesome to apply the concept of natural behaviour to animals that have changed their behavioural repertoire through many generations of breeding, such as cattle bred for high milk production (Jensen, 2006; Anon., 2009d). A behaviour might not qualify natural just because it occurs often in a large percentage of animals, occurs under unconfined conditions, satisfies a strong intrinsic drive or results from genetic adaptation with no direct human interference. Algers (1992) suggested that a behaviour is natural if the animal is strongly motivated to perform it and, when performing it, receives functional feedback. According to Algers, functional feedback should be understood as interaction with the environment in a way determined by genes and previous experience. This adheres well to Aristotelian ethics, in which an animal should be able to live and develop according to its telos (purpose or function for which it was biologically evolved). This logic seems to fit well with the public request for naturalness in animal production; that animals should be able to behave naturally, but also that there should be natural elements in their environment. Since long it has been argued that the natural sciences and the humanities constitute separate cultural realms with little mutual understanding and communication. However, neither empirical information nor ethical reflection alone can answer questions about our proper relationship with other species. The notion that subjective experience should not be included in scientific study stems from a strain of philosophy of science called positivism (Rollin, 1990), which attempted to separate science and metaphysics and claimed that we should not postulate unobservable processes to explain observable ones. Tannenbaum (1991), Lund and Röcklinsberg (2001), Sandøe et al. (2003), Fraser (2008a) and others have recognized that animal ethics and animal welfare sciences are inherently linked to each other, and that ethicists and philosophers have important roles to play in animal welfare science. Tannenbaum argued that normative choices should be made explicit, that goodness is the central evaluative concept in animal welfare and that philosophers can help scientists in the evaluation. More recently, the combination of animal welfare science and ethics has gained recognition and attracted growing interest internationally, as reflected in the names of scientific institutions, courses and government bodies. It has been suggested that animal welfare and animal ethics should be taught together in agricultural and veterinary education (Edwards, 2002; Hanlon, 2008), and an increasing number of institutions provide education in animal welfare science, ethics and law (Main et al., 2005; Broom, 2010). The dualistic view separating ethics and science is, however, still influential. Scientists often adopt a minimalistic strategy, relating animal welfare to more easily measured states, such as health or behaviour, thus avoiding elusive and possibly controversial manifestations of poor welfare like negative emotions or lack of integrity (Rollin, 1995). This may be a problematic position because, if values that the public regard as central to animal welfare are highly disregarded, it may undermine public trust in expert judgement and opinion (Fraser et al., 1997). Furthermore, by avoiding and excluding some manifestations of poor welfare, researchers may, in fact, overestimate welfare (Verhoog, 2000).

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Key issues in the welfare of dairy cattle37

4.3 Differing perceptions of animal welfare among citizens and stakeholders In light of the idea that there is no simple truth about the nature of animal welfare, nor about which issues are most relevant to consider, it may be intuitively appealing to include subjective attitudes and opinions in the discussion. By asking people about their perceptions of animal welfare and what they think are acceptable, poor or excellent animal welfare conditions, it may be possible to get a comprehensive view of the most common views among a broad spectrum of citizens and stakeholders. Roex and Miele (2005) recognized that the view on animals and animal welfare varies between different groups of European producers, retailers and consumers. While producers tend to draw mainly on scientific understandings and consider animal health, consumers have some humanistic preferences and tend to give the animals a status as subjects, and animal rights advocates have an almost purely humanistic understanding. This research revealed a widespread perception in stakeholders that confined systems of production are inherently detrimental to the welfare of farm animals, but also that stakeholders overall lack knowledge of contemporary farming practices. Other researchers have found that veterinarians and farmers generally tend to relate animal welfare to health, while citizens relate more to natural behaviour (Vanhonacker et al., 2008). A number of studies have shown a great concern for animal welfare issues among the citizens in many industrialized countries. Eurobarometers and other surveys have shown that a high percentage of European and North American citizens see animal welfare as an important issue, and that they have worries about the welfare of farm animals (Zogby, 2003; Anon., 2015c, 2016d; Schuppli et al., 2014). Forty-four per cent of surveyed adult consumers in the United States said they wanted to know more about how food companies treat the animals used in their products (Anon., 2015c). About the same percentage (47%) said they supported companies that avoid inhumane treatment of animals. In addition, almost two-thirds indicated that they wanted animals raised in as natural an environment as possible. Lusk and Norwood (2008) found that a majority (56%) of respondents in randomly chosen households of the United States believed decisions about farm animal welfare should be made by experts rather than being based on the views of the public, and that decisions should rest on scientific measures of animal well-being, as opposed to moral and ethical considerations. Interestingly, respondents who believed farm animal welfare decisions should be made by experts and be based on scientific measures were the least concerned about farm animal welfare issues. Farming experience and value orientation appear to influence attitudes and preferences regarding milk production. Dutch citizens with experience or knowledge of farming (through visits, work or rural residency) have been found to be more satisfied with contemporary dairy farming, more accepting of modern husbandry practices and more willing to pay for added values than those who had less experience or knowledge (Boogaard et al., 2011). The public views on animal welfare in the so-called emerging economies of Asia and Latin America are of special interest. Despite the fact that China counts with the largest dairies and is one of the largest producers of bovine milk in the world (Anon., 2016f), animal welfare in China is, in effect, still in its infancy. You et al. (2014) investigated public

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Key issues in the welfare of dairy cattle

attitudes to animal welfare in China, with a focus on pigs and fowls. Two-thirds of the respondents had never heard of animal welfare. However, almost three-fourths claimed that, for the sake of food safety, the rearing conditions should be improved.

5 Recommendations for improving animal welfare in dairy farming in the light of expected future developments 5.1  Continued intensification With the present pace of development of the dairy sector in the industrialized world, we should expect continued intensification with fewer and larger dairy farms, increased milk yields, increased automation of herd management, continued internationalization of milk processor companies and dairy product trade, shrinking profit margins of milk farmers and further production cost cuts. Unfortunately, a unilateral focus on intensified milk production, which by some is considered the best way forward, is likely to aggravate many animal welfare problems. The urge for further intensification ignores the fact that many citizens tend to reject industrial animal production, at least partly attributing this to reduced animal welfare (Hardeman and Jochemsen, 2012; Hötzel, 2014). Consumer demand for cheap, safe and ethically sound milk products will continue, creating incentives for quality assurance based on efforts for sustained or improved animal welfare, as well as biosecurity, limited drug use, reduced environmental impact and a desirable agricultural landscape. A great deal of research is likely to be directed at dealing with the multitude of potential conflicts of interests that follow from the aspirations for sustainability. To achieve significant improvements in the welfare of dairy cattle and thus sustainable milk production, we need to envisage arrangements that allow us to predict, assess and communicate the consequences of remedial actions at all levels of the food chain, and policies that permit efficient and ethically acceptable milk production systems to flourish. The future successful milk farmer will be most likely skilled in animal and staff management, scientifically knowledgeable, with a professional ethic of animal care and a great understanding of the need to conform to legislation, standards and societal expectations. Below, a number of prioritized areas are indicated, where further research and remedial actions are required.

5.2  Prioritized areas The most effective route to stop the decline of animal welfare caused by unilateral genetic selection for high milk yield is by adopting a selection index in which welfare-related traits such as health, fertility and longevity are included and appropriately weighted (RodríguezMartínez et al., 2008; Anon., 2009d). Already in 1997, the United Kingdom’s Farm Animal Welfare Council stressed the paramount importance of good welfare in breeding programmes, and recommended that ‘breeding companies should devote their efforts primarily to selection for health traits so as to reduce current levels of lameness, mastitis and infertility’ (Anon., 1997). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle39

A global and multi-sector system for surveillance of antibiotic use and antimicrobial resistance is urgently needed (Anon., 2016a,b,c), as a first step towards limiting imprudent use of antibiotics that will potentially threaten future animal health care and welfare. The use of hormones in dairy cattle should be limited to therapeutic contexts. Research and surveillance is needed to reveal animal health risks associated with ongoing climate change, for example, through spread of disease vectors to new regions. Whenever possible, dairy cattle should be allowed access to pasture. Rearing together with the dam can provide health and welfare benefits for the calf (Krohn, 2001; Flower and Weary, 2003). Cow and calf response to separation increases when the calf spends more time with the dam, but there may be long-term benefits of prolonged contact in terms of sociality, fearfulness, health and future maternal behaviour. Research is needed in order to develop functional dairy management systems that respect the natural social behaviour of cows and calves during the calf-rearing period (Johnsen et al., 2016). There is also a need to address ways to control transmissible diseases when dairy cattle are kept in mixed age groups. In general, mutilations should be avoided. Routine tail docking should not be allowed. When performed, painful procedures such as castration and disbudding should be accompanied by sedation, local anaesthesia and post-operative anti-inflammatory treatment. Research is needed to elucidate the effects of painful procedures on calves of different ages. The susceptibility of cattle to challenges during potentially demanding conditions like restraint, transport and slaughter depend to a great extent on the animals’ previous experiences. Gentle interaction with humans early in life and training of cattle for future restraint and human handling can reduce animal stress (Grandin, 1998; Probst et al., 2012). Animal handling can be improved through vocational education and training programmes aimed at improving attitudes and behaviour of handlers towards their animals (Hemsworth et al., 2002). A relatively new area of great potential is precision dairy farming, which is the use of technologies to measure physiological, behavioural and production indicators on individual animals to improve management strategies and farm performance (Bewley, 2010). Precision dairy management technologies provide great opportunities for improvements in individual animal management on milk farms (Bewley et al., 2015). Cow-level recordings from automated feeding systems for calves and cows, automatic milking systems, devices relying on the global positioning system, pedometry and biotelemetry result in huge amounts of data, so far used only in a very small degree. Automatic monitoring equipment is already developed and will be used increasingly to record milk yield and composition, body temperature and activity in order to identify cows in oestrus, cows that are about to calve, lame cows, mastitic cows and fresh cows that are off feed. New technical solutions will probably be developed to continuously monitor heart and respiration rates, chewing activity, gas emissions and to detect rumen dysfunction and deviations in body condition (Fig. 8). Animal transportation should be reduced. Network analysis has shown that strategic planning of cattle slaughter transports in Sweden can reduce total transport distances by 40%, without changing the choice of abattoir and slaughter capacity, and if all cattle were sent to the nearest plant, distances could be reduced by 60% (Håkansson, 2012). There are prospects for small-scale and mobile on-farm slaughter of cattle, which would eliminate or reduce transportation and potentially reduce pre-slaughter stress. In mobile slaughter, a self-contained unit housed in a road vehicle is taken to the farm, instead of © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Key issues in the welfare of dairy cattle

Body temperature

Rumen activity and pH Vaginal activity

Chewing activity

Body condition

Methane emission Respiration rate Location

Feed and water intake Locomotor activity

Heart rate Lying behaviour

Udder skin temperature Milk contents and conductivity

Milk yield

Figure 8 Presently or soon available measurements for automatic monitoring of cows to support precision dairy farming (Photo: J. Svennås-Gillner, Swedish University of Agricultural Sciences).

transporting the animals live to an abattoir. Håkansson (2012) found that small-scale and mobile slaughter would have only a limited effect on total transport distance but would cut the longest distances. An efficient way to reduce stress in dairy cattle at large-scale abattoirs is to ensure that facilities and equipment for animal handling allow for smooth and effective forward movement of animals, and that handlers understand and respect the principles of good human–animal interaction (Grandin, 2013). Effective stunning methods should always be applied before sticking.

5.3  Assessment and communication of animal welfare Development of practically useful methods for regular assessment of the level of animal welfare in dairy herds is needed (Anon., 2012b). To be credible, such methods must integrate all aspects of animal welfare relevant to the public, including respect for naturalness. Risk assessment can be used to identify major risks for poor welfare (Anon., 1999; Algers, 2009; Paton et al., 2013), thus directing policies, prevention and official control. However, as discussed above, welfare determinants and manifestations are inherently complex, and currently used methods for risk assessment have several unresolved methodological limitations (reviewed by Müller-Graf et al., 2008; Smulders, 2009; Anon., 2010a), calling for alternative approaches. Further data on the effects of determinants of dairy cattle welfare are needed to reduce uncertainty and allow for quantitative risk assessment. Research is also needed to facilitate monitoring and surveillance of farm animal welfare risks at national and international levels, utilizing databases created for other purposes (Dewey et al., 2009; Houe et al., 2011; Nyman et al., 2011). The consumption of specially labelled products and its role in improving the welfare of livestock have attracted considerable attention (Heerwagen et al., 2015). There is a diverse market for welfare-friendly products and services. Apart from legal regulation, © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle41

voluntary welfare-based certification and assurance play an important role in promoting such products (Mellor and Bayvel, 2008; Mench, 2008; Veissier et al., 2008; KilBride et al., 2012; Heath et al., 2014). It is essential that milk products be presented transparently and fairly, to limit the risk for ethical conflict and misunderstanding (Bunting and Galyean, 2015). Undue profit by wrongly presenting the products as ‘natural’ should be avoided in order not to mislead consumers and risk losing valuable confidence among citizens (Borkfelt et al., 2015). The ongoing intensification of milk production does not appear to address this issue sufficiently.

6 Summary Despite obvious progress in production efficiency in the last century, the overall positive effects of intensive milk production on animal welfare are rightly questioned. A large number of factors influence the welfare of dairy cattle, not least husbandry conditions. The determinants and manifestations of animal welfare are inherently complex, which complicates proper assessment and communication of welfare issues. Some areas for further research and action are identified. Genetic selection should include welfare-related traits. International surveillance of antibiotic use and resistance is urgent. Dairy management systems that respect the natural social behaviour of cattle should be developed. Mutilations should be avoided if possible and, if performed, accompanied by proper analgesic treatment. Facilities and equipment for animal handling should allow for smooth and effective movement of animals, and handlers need to understand and respect the principles of good human–animal interaction. At slaughter, effective stunning methods should always be applied before sticking. The urge for further intensification ignores the fact that many citizens tend to reject industrial animal production, at least partly because of reduced animal welfare. Unfortunately, a unilateral focus on intensified milk production, which by some is considered the best way forward, is likely to aggravate many animal welfare problems. Significant improvements in the welfare of dairy cattle and thus sustainable milk production will require arrangements that allow prediction, assessment and communication of the consequences of remedial actions at all levels of the food chain, and policies that permit efficient and ethically acceptable milk production systems to flourish. The welfare of farm animals would improve if the gap between producers and consumers is bridged.

7  Where to look for further information There is a rich flora of textbooks on dairy cattle welfare and related subjects. Examples that the reader may find useful are (in alphabetical order) Aland and Madec (2009), Appleby et al. (2011, 2014), Blokhuis et al. (2013), Broom (2014), Broom and Johnson (2000), Fraser (2008b), Gjerris et al. (2013), Haynes (2008), Hemsworth and Coleman (2011), Mellor et al. (2009), Rushen et al. (2008) and Webster (2005, 2011). Fraser et al. (2013) wrote a review to illustrate the broad range of science relevant to animal welfare and its application to animal welfare standards and practices, using OIE principles as a framework. Barkema et al. (2015) conducted an excellent review on contemporary issues specifically pertaining to the welfare of dairy cattle. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Scientific work related to dairy cattle welfare is published in a large number of scientific journals, among which can be found (in alphabetical order) AMBIO, Animal, Animal Welfare, Anthrozoös, Applied Animal Behaviour Science, Journal of Animal Science, Journal of Dairy Science, Journal of Agricultural and Environmental Ethics, Livestock Science and PLoS ONE. Further journals can be identified by scrolling the reference list at the bottom of this chapter. The OIE and the Food and Agricultural Organization of the United Nations (FAO) play prominent roles in animal welfare worldwide. In 2013, an OIE Regional Platform on animal welfare for Europe was formed, with the purpose to empower veterinary services to take action on animal welfare in compliance with OIE standards. In a special issue of its Scientific and Technical Review, OIE outlined contemporary thinking about factors that promote or jeopardize the productivity, health and welfare of the wide range of animals used for human purposes, including dairy cattle (Mellor and Bayvel, 2014). The European region is leading in the development of animal welfare policies. Common animal welfare issues in the European Union are the responsibility of health and consumer issues Directorate General, the DG SANCO. The European Commission has websites dedicated to animal health, animal welfare and related educational efforts. EFSA undertakes scientific work on animal health and welfare through its Scientific Panel on Animal Health and Animal Welfare, mostly in response to requests from the commission. A European network of animal welfare reference centres has been considered and national centres exist in Denmark (DCAW), Finland (EHK) and Sweden (SCAW). A large number of professional societies aim to promote a better understanding of animal welfare and the human–animal relationship, through scientific and educational activities. Examples are the International Society for Applied Ethology (ISAE), the Universities Federation for Animal Welfare (UFAW) and the European Society for Agricultural and Food Ethics (EurSafe). These societies organize international congresses every one or two years. Applied Animal Behaviour Science is the official journal of ISAE, and Animal Welfare is the official journal of UFAW. In recent years, there have been a number of major EU-financed research initiatives. Notable examples are the Welfare Quality® project 2004–9, the Encouraging Dialogue on Issues of Religious Slaughter (DIALREL) project 2006–10, the European Animal Welfare Platform (EAWP) 2008–11, the Socio Economic Aspects of Farm Animal Welfare (EconWelfare) project 2008–11, the Alternatives to Castration and Dehorning (ALCASDE) project 2009, the Animal Welfare Indicators (AWIN) project starting in 2010, the Animal Welfare Research in an Enlarged Europe (AWARE) project 2011–14, the Animal Health and Welfare ERA-Net (ANIHWA) project 2012–15 and the EU project on the establishment of a coordinated European network for animal welfare (EUWelNet) 2013. Examples of dairy cattle welfare research centres in the forefront are (in alphabetical order) Aarhus University, Denmark; Bristol University and Newcastle University, UK; the French National Institute of Agricultural Research (INRA), France; the Swedish University of Agricultural Sciences, Sweden; the University of British Columbia, Canada; and Wageningen University and Research Centre, the Netherlands.

8 Acknowledgements I am extremely grateful for the willingness of researchers Helena Röcklinsberg, Lotta Berg and Stefan Gunnarsson at the Swedish University of Agricultural Sciences to review and © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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comment on an early manuscript, and for enlightening and rewarding discussions with colleagues at the Department of Animal Environment and Health in Skara and Uppsala, Sweden over the years.

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http://liu.diva-portal.org/smash/record.jsf?pid=diva2%3A514097&dswid=-7653 (accessed 26 February 2016). Heath, C. A. E., Lin, Y., Mullan, S., Browne, W. J. and Main, D. C. J. (2014), Implementing Welfare Quality® in UK assurance schemes: evaluating the challenges, Anim. Welf., 23, 95–107. Heerwagen, L. R., Mørkbak, M. R., Denver, S., Sandøe, P. and Christensen, T. (2015), The role of quality labels in market-driven animal welfare, J. Agric. Environ. Ethics, 28, 67–84. Hemsworth, P. H. (2003), Human-animal interactions in livestock production, Appl. Anim. Behav. Sci., 81, 185–98. Hemsworth, P. H. (2009), Impact of human-animal interactions on the health, productivity and welfare of farm animals, in A. Aland and F. Madec (eds), Sustainable Animal Production. The Challenges and Potential Developments for Professional Farming, Wageningen Academic Publ., Wageningen, The Netherlands, pp. 57–68. Hemsworth, P. H. and Coleman, G. J. (2011), Human-Livestock Interactions: The Stockperson and the Productivity and Welfare of Intensively Farmed Animals, 2nd ed., Wallingford, UK and Cambridge, USA, http://www.cabi.org/cabebooks/ebook/20103380749 (accessed 26 February 2016). Hemsworth, P. H., Coleman, G. J., Barnett, J. L., Borg, S. and Dowling, S. (2002), The effects of cognitive behavioral intervention on the attitude and behavior of stockpersons and the behavior and productivity of commercial dairy cows, J. Anim. Sci., 80, 68–78. Hemsworth, P. H., Rice, M., Karlen, M. G., Calleja, L. Barnett, J. L., Nash, J. and Coleman, G. J. (2011), Human–animal interactions at abattoirs: Relationships between handling and animal stress in sheep and cattle, Appl. Anim. Behav. Sci., 135, 24–33. Hernandez-Mendo, O., von Keyserlingk, M. A. G., Veira, D. M. and Weary, D. M. (2007), Effects of pasture on lameness in dairy cows, J. Dairy Sci., 90, 1209–14. Hötzel, M. J. (2014), Improving farm animal welfare: is evolution or revolution needed in production systems?, in M. C. Appleby, D. M. Weary and P. Sandøe (eds), Dilemmas in Animal Welfare, CAB International, Wallingford, UK and Boston USA, pp. 67–84, http://www.cabi.org/cabebooks/ ebook/20143138804 (accessed 26 February 2016). Houe, H., Gardner, I. A. and Rosenbaum Nielsen, L. (2011), Use of information on disease diagnoses from databases for animal health economic, welfare and food safety purposes: strengths and limitations of recordings, Acta Vet. Scand., 53(Suppl. 1), S7. Hultgren, J., Wiberg, S., Berg, L., Cvek, K. and Lunner Kolstrup, C. (2014), Cattle behaviours and stockperson actions related to impaired animal welfare at Swedish slaughter plants, Appl. Anim. Behav. Sci., 152, 23–37. Ingvartsen, K. L., Dewhurst, R. J. and Friggens, N. C. (2003), On the relationship between lactational performance and health: is it yield or metabolic imbalance that cause production diseases in dairy cattle? A position paper, Livest. Prod. Sci., 83, 277–308. Jensen, P. (2006), Domestication – from behaviour to genes and back again, Appl. Anim. Behav. Sci., 97, 3–15. Johnsen, J. F., de Passille, A. M., Mejdell, C. M., Bøe, K. E., Grøndahl, A. M., Beaver, A., Rushen, J. and Weary, D. M. (2015), The effect of nursing on the cow–calf bond, Appl. Anim. Behav. Sci., 163, 50–7. Johnsen, J. F., Zipp, K. A., Kälber, T., de Passillé, A. M., Knierim, U., Barth, K. and Mejdell, C. M. (2016), Is rearing calves with the dam a feasible option for dairy farms? – Current and future research, Appl. Anim. Behav. Sci., in press. KilBride, A. L., Mason, S. A., Honeyman, P. C., Pritchard, D. G., Hepple, S. and Green, L. E. (2012), Associations between membership of farm assurance and organic certification schemes and compliance with animal welfare legislation, Vet. Rec., 170, 152–9. Krohn, C. C. (2001), Effects of different suckling systems on milk production, udder health, reproduction, calf growth and some behavioural aspects in high producing dairy cows – a review, Appl. Anim. Behav. Sci., 72, 271–80. Laxminarayan, R., Duse, A., Wattal, C., Zaidi, A. K. M., Wertheim, H. F. L., Sumpradit, N., Vlieghe, E., Levy Hara, G., Gould, I. M., Goossens, H., Greko, C., So, A. D., Bigdeli, M., Tomson, G., Woodhouse, W., Ombaka, E., Quizhpe Peralta, A., Naz Qamar, F., Mir, F., Kariuki, S., Bhutta, Z. A., © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Key issues in the welfare of dairy cattle49 Coates, A., Bergstrom, R., Wright, G. D., Brown, E. D. and Cars, O. (2013), Antibiotic resistance – the need for global solutions, Lancet Infect. Dis., 13, 1057–98. Legrand, A. L., von Keyserlingk, M. A. G. and Weary, D. M. (2009), Preference and usage of pasture versus free-stall housing by lactating dairy cattle, J. Dairy Sci., 92, 3651–8. Lensink, B. J., Raussi, S., Boivin, X., Pyykkönen, M. and Veissier, I. (2001), Reactions of calves to handling depend on housing condition and previous experience with humans, Appl. Anim. Behav. Sci., 70, 187–99. Loizzo, A., Loizzo, S. and Capasso, A. (2009), Neurobiology of pain in children: an overview, Open Biochem. J., 3, 18–25. Lund, V. (2006), Natural living – a precondition for animal welfare in organic farming, Livest. Sci., 100, 71–83. Lund, V. and Röcklinsberg, H. (2001), Outlining a conception of animal welfare for organic farming systems, J. Agric. Environ. Ethics, 14, 391–424. Lundmark, F., Berg, L., Wahlberg, B. and Röcklinsberg, H. (2015), ‘One animal is no animal’ – consequences of measuring animal welfare at herd level, in D. E. Dumitras, I. M. Jitea and S. Aerts (eds), Know your Food. Food Ethics and Innovation, Proc. EurSafe Congr., Cluj-Napoca, Romania, 28–30 May 2015, pp. 31–5. Lürzel, S., Münsch, C., Windschnurer, I., Futschik, A., Palme, R. and Waiblinger, S. (2015), The influence of gentle interactions on avoidance distance towards humans, weight gain and physiological parameters in group-housed dairy calves, Appl. Anim. Behav. Sci., 172, 9–16. Lusk, J. L. and Norwood, F. B. (2008), A survey to determine public opinion about the ethics and governance of farm animal welfare, J. Am. Vet. Med. Assoc., 233, 1121–6. Main, D. C., Thornton, P. and Kerr, K. (2005), Teaching animal welfare science, ethics, and law to veterinary students in the United Kingdom, J. Vet. Med. Educ., 32, 505–8. McInerney, J. P. (2002), Animal welfare: ethics, economics and productivity, livestock improvement corporation lecture, Proc. NZ Soc. An. Prod., 62, 340–7. Medrano-Galarza, C., Gibbons, J., Wagner, S., de Passillé, A. M. and Rushen, J. (2012), Behavioral changes in dairy cows with mastitis, J. Dairy Sci., 95, 6994–7002. Medugorac, I., Seichter, D., Graf, A., Russ, I., Blum, H., Göpel, K. H., Rothammer, S., Förster, M. and Krebs, S. (2012), Bovine polledness – an autosomal dominant trait with allelic heterogeneity, PLoS ONE, 7, e39477. Mellor, D. J. and Bayvel, A. C. D. (2008), New Zealand’s inclusive science-based system for setting animal welfare standards, Appl. Anim. Behav. Sci., 113, 313–29. Mellor, D. J. and Bayvel, A. C. D. (eds) (2014), Animal welfare: focusing on the future, World Organisation for Animal Health, Paris, France, Rev. Sci. Tech. Off. Int. Epiz., 33, 1–328, http:// web.oie.int/boutique/index.php?page=ficprod&id_produit=1307&fichrech=1&lang=en (accessed 26 February 2016). Mellor, D. J., Patterson-Kane, E. and Stafford, K. J. (2009), The Sciences of Animal Welfare, WileyBlackwell, Wheathampstead, UK. Mench, J. A. (2008), Farm animal welfare in the U.S.A.: Farming practices, research, education, regulation, and assurance programs, Appl. Anim. Behav. Sci., 113, 298–312. Menke, C., Waiblinger, S., Fölsch, D. W. and Wiepkema, P. R. (1999), Social behaviour and injuries of horned cows in loose housing systems, Anim. Welf., 8, 243–58. Müller-Graf, C., Candiani, C., Barbieri, S., Ribo, O., Afonso, A., Aiassa, E., Have, P., Correia, S., De Massis, F., Grudnik, T. and Serratosa, J. (2008), Risk assessment in animal welfare – EFSA approach, Proc. 6th World Congr. Altern. Anim. Use Life Sci., Tokyo, Japan, 21–25 August 2007, AATEX 14, Special Issue, 789–94, http://altweb.jhsph.edu/wc6/paper789.pdf (accessed 26 February 2016). Nyman, A.-K., Lindberg, A. and Hallén Sandgren, C. (2011), Can pre-collected register data be used to identify dairy herds with good cattle welfare? Acta Vet. Scand., 53 (Suppl. 1), S8. Oltenacu, P. A. and Broom, D. M. (2010), The impact of genetic selection for increased milk yield on the welfare of dairy cows, Anim. Welf., 19(S), 39–49. Oltenacu, P. A., Frick, A. and Lindhé, B. (1990), Epidemiological study of several clinical diseases, reproductive performance and culling in primiparous Swedish cattle, Prev. Vet. Med., 9, 59–74. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Paton, M. W., Martin, P. A. J. and Fisher, A. D. (2013), Risk assessment principles in evaluation of animal welfare, Anim. Welf., 22, 277–85. Popescu, S., Borda, C., Diugan, E. A., Niculae, M., Stefan, R. and Sandru, C. D. (2014), The effect of the housing system on the welfare quality of dairy cows, Ital. J. Anim. Sci., 13, 15–22. Popescu, S., Borda, C., Diugan, E. A., Spinu, M., Groza, I. S. and Sandru, C. D. (2013), Dairy cows welfare quality in tie-stall housing, system with or without access to exercise, Acta Vet. Scand., 55, 43. Probst, J. K., Spengler Neff, A., Leiber, F., Kreuzer, M. and Hillmann, E. (2012), Gentle touching in early life reduces avoidance distance and slaughter stress in beef cattle, Appl. Anim. Behav. Sci., 139, 42–9. Proudfoot, K. L., Weary, D. M. and von Keyserlingk, M. A. G. (2012), Linking the social environment to illness in farm animals, Appl. Anim. Behav. Sci., 138, 203–15. Pryce, J. E. and Veerkamp, R. F. (2001), The incorporation of fertility indices in genetic improvement programmes, in M. G. Diskin (ed.), Fertility in the High-Producing Dairy Cow, Proc. Occ. Mtg. Galway, Ireland, 20–22 September 1999, BSAS Occ. Publ., 26, 237–49. Rauw, W. M., Kanis, E., Noordhuizen-Stassen, E. N. and Grommers, F. J. (1998), Undesirable side effects of selection for high production efficiency in farm animals: a review, Livest. Prod. Sci., 56, 15–33. Rodríguez-Martínez, H. Hultgren, J., Båge, R., Bergqvist, A. -S., Svensson, C., Bergsten, C., Lidfors, L., Gunnarsson, S., Algers, B., Emanuelson, U., Berglund, B., Andersson, G., Lindhé, B., Stålhammar, H. and Gustafsson, H. (2008), Reproductive performance in high-producing dairy cows: can we sustain it under current practice? IVIS Rev.Vet. Med., R01, R0108, 1–23. Roex, J. and Miele, M. (eds) (2005), Farm Animal Welfare Concerns. Consumers, Retailers and Producers, Welfare Quality Reports No. 1, School of City and Regional Planning, Cardiff University, Cardiff, UK, http://www.welfarequality.net/everyone/34056/5/0/22 (accessed 26 February 2016). Rollin, B. E. (1990), The Unheeded Cry, Oxford University Press, Oxford, UK. Rollin, B. E. (1995), Farm Animal Welfare: Social, Bioethical, and Research Issues, Iowa State Univ. Press, Ames, USA. Rouha-Mülleder, C., Iben, C., Wagner, E., Laaha, G., Troxler, J. and Waiblinger, S. (2009), Relative importance of factors influencing the prevalence of lameness in Austrian cubicle loose-housed dairy cows, Prev. Vet. Med., 92, 123–33. Rushen, J., de Passillé, A. M., von Keyserlingk, M. A. G. and Weary, D. M. (2008), The Welfare of Cattle, Springer, Dordrecht, The Netherlands. Rushen, J., Taylor, A. A. and de Passille, A. M. (1999), Domestic animals’ fear of humans and its effect on their welfare, Appl. Anim. Behav. Sci., 65, 285–303. Rutherford, K. M. D., Langford, F. M., Jack, M. C., Sherwood, L., Lawrence, A. B. and Haskell, M. J. (2008), Hock injury prevalence and associated risk factors on organic and nonorganic dairy farms in the United Kingdom, J. Dairy Sci., 91, 2265–74. Rutten, C. J., Velthuis, A. G. J., Steeneveld, W. and Hogeveen, H. (2013), Invited review: Sensors to support health management on dairy farms, J. Dairy Sci., 96, 1928–52. Sandøe, P., Christiansen, S. B. and Appleby, M. C. (2003), Farm animal welfare: the interaction of ethical questions and animal welfare science, Anim. Welf., 12, 469–78. Schuenemann, G. M., Bas, S. Gordon, E. and Workman, J. D. (2013), Dairy calving management: Description and assessment of a training program for dairy personnel, J. Dairy Sci., 96, 2671–80. Schuppli, C. A., von Keyserlingk, M. A. G. and Weary, D. M. (2014), Access to pasture for dairy cows: Responses from an online engagement, J. Anim. Sci., 92, 5185–92. Simensen, E., Østerås, O., Bøe, K. E., Kielland, C., Ruud, L. E. and Næss, G. (2010), Housing system and herd size interactions in Norwegian dairy herds; associations with performance and disease incidence, Acta Vet. Scand., 52, 14. Smulders, F. J. M. (2009), A practical approach to assessing risks for animal welfare – methodological considerations, in F. J. M. Smulders and B. Algers (eds), Welfare of Production Animals: Assessment and Management of Risks, Food safety assurance and veterinary public health, vol. 5, Wageningen Academic Publishers, Wageningen, The Netherlands, pp. 239–74.

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Key issues in the welfare of dairy cattle51 Stafford, K. J. and Mellor, D. J. (2005), Dehorning and disbudding distress and its alleviation in calves, Vet. J., 169, 337–49. Stěhulová, I., Lidfors, L. and Špinka, M. (2008), Response of dairy cows and calves to early separation: Effect of calf age and visual and auditory contact after separation, Appl. Anim. Behav. Sci., 110, 144–65. Stock, M. L., Baldridge, S. L., Griffin, D. and Coetzee, J. F. (2013), Bovine dehorning. Assessing pain and providing analgesic management, Vet. Clin. North Am.: Food Anim. Pract., 29, 103–33. Sutherland, M. A. and Tucker, C. B. (2011), The long and short of it: A review of tail docking in farm animals, Appl. Anim. Behav. Sci., 135, 179–91. Svensson, C. and Jensen, M. B. (2007), Identification of diseased calves by use of data from automatic milk feeders, J. Dairy Sci., 90, 994–7. Svensson, C. and Liberg, P. (2006), The effect of group size on health and growth rate of Swedish dairy calves housed in pens with automatic milk-feeders, Prev. Vet. Med., 73, 43–53. Svensson, C., Linder, A. and Olsson, S.-O. (2006), Mortality in Swedish dairy calves and replacement heifers, J. Dairy Sci., 89, 4769–77. Svensson, C., Lundborg, K., Emanuelson, U. and Olsson, S. O. (2003), Morbidity in Swedish dairy calves from birth to 90 days of age and individual calf-level risk factors for infectious diseases, Prev. Vet. Med., 58, 179–97. Tannenbaum, J. (1991), Ethics and animal welfare: the inextricable connection, J. Am. Vet. Med. Assoc., 198, 1360–76. Terlouw, E. M. C., Arnould, C., Auperin, B., Berri, C., Le Bihan-Duval, E., Deiss, V., Lefévre, F., Lensink, B. J. and Mounier, L. (2008), Pre-slaughter conditions, animal stress and welfare: current status and possible future research, Anim., 2, 1501–17. Thomsen, P. T., Østergaard, S., Sørensen, J. T. and Houe, H. (2007), Loser cows in Danish dairy herds: definition, prevalence and consequences, Prev. Vet. Med., 79, 116–35. Thorpe, W. H. (1965), The assessment of pain and distress in animals, in F. W. Rogers Brambell (ed.), ‘Report of the technical committee to enquire into the welfare of animals kept under intensive livestock husbandry systems’, Appendix III, Her Majesty’s Stationary Office, London, UK, pp. 71–9. Uetake, K. (2013), Newborn calf welfare: a review focusing on mortality rates, Anim. Sci. J., 84, 101–5. Valníčková, B., Stěhulová, I., Šárová, R. and Špinka, M. (2015), The effect of age at separation from the dam and presence of social companions on play behavior and weight gain in dairy calves, J. Dairy Sci., 98, 5545–56. Van Nuffel, A., Zwertvaegher, I., Pluym, L, Van Weyenberg, S., Thorup, V. M., Pastell, M., Sonck, B. and Saeys, W. (2015), Lameness detection in dairy cows: Part 1. How to distinguish between non-lame and lame cows based on differences in locomotion or behavior, Anim., 5, 838–60. Vanhonacker, F., Verbeke, W., Van Poucke, E. and Tuyttens, F. A. M. (2008), Do citizens and farmers interpret the concept of farm animal welfare differently? Livest. Sci., 116, 126–36. VanRaden, P. M. (2004), Selection on net merit to improve lifetime profit, J. Dairy Sci., 87, 3125–31. Vasseur, E., Borderas, F., Cue, R. I., Lefebvre, D., Pellerin, D., Rushen, J., Wade, K. M. and de Passillé, A. M. (2010a), A survey of dairy calf management practices in Canada that affect animal welfare, J. Dairy Sci., 93, 1307–15. Vasseur, E., Rushen, J., de Passillé, A. M., Lefebvre, D. and Pellerin, D. (2010b), An advisory tool to improve management practices affecting calf and heifer welfare on dairy farms, J. Dairy Sci., 93, 4414–26. Veerkamp, R. F., Beerda, B. and van der Lende, T. (2003), Effects of genetic selection for milk yie1d on energy balance, levels of hormones, and metabolites in lactating cattle, and possible links to reduced fertility, Livest. Prod. Sci., 83, 257–75. Veissier, I., Andanson, S., Dubroeucq, H. and Pomiès, D. (2008), The motivation of cows to walk as thwarted by tethering, J. Anim. Sci., 86, 2723–9. Veissier, I., Butterworth, A., Bock, B. and Roe, E. (2008), European approaches to ensure good animal welfare, Appl. Anim. Behav. Sci., 113, 279–97.

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Chapter 3 Housing and the welfare of dairy cattle Jeffrey Rushen, University of British Columbia, Canada 1 Introduction

2 Types of housing system



3 Stall design



4 Flooring and locomotion



5 Social competition, social dominance and overstocking



6 Group versus individual housing for un-weaned calves: effects on health, locomotion and rest



7 Group versus individual housing for un-weaned calves: behaviour and weight gain



8 Reflections on housing un-weaned calves individually, in groups and with cows

9 Conclusions

10 Where to look for further information

11 References

1 Introduction Despite the images of cows with their calves in a field that are used to sell milk, very few lactating dairy cattle in Europe or North America are kept this way. In North America many (if not most) lactating cows are kept in indoor housing throughout the year (so-called ‘zero grazing’), while the vast majority of calves are separated from their mothers within hours or at most days of birth, and many of these are housed indoors. Housing conditions affect animals throughout their life. Many modern housing systems involve keeping animals indoors, in a restricted space, often at high density and separated from other animals, which raises concerns about the animals’ welfare. Housing can impact animal welfare mainly by changing the risk that animals will suffer from health and injuries, or by placing restrictions on their behaviour. In this chapter, I examine some of research that has been done into the welfare issues that arise from the physical and social aspects of the housing. Covering all aspects of the housing of dairy cattle is beyond the scope of this chapter and so I focus on some of the more current and controversial aspects of how the housing method impacts the animals’ welfare. Since the lactating cow and un-weaned calves are the dairy animals most at risk of welfare problems, (and for which most research has been done) I restrict the review to these. http://dx.doi.org/10.19103/AS.2016.0006.03 © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Housing and the welfare of dairy cattle

2  Types of housing system The most commonly used indoor housing systems for dairy cows can be grouped into tie-stalls (Fig. 1) (in which the cows are kept tethered and often milked in a stall) and loose housing (in which the cows are not tied and usually milked in a parlour or with an automated milking system). The latter includes free-stall or cubicle systems (Fig. 2), in which the cows have access to a lying stall, and deep-bedded systems, such as straw packs or deep-bedded compost systems, in which cows are free to lie down wherever they wish within the bedded area (Fig. 3).

Figure 1 Free-stall housing (or cubicle housing) is the most commonly used indoor group housing for dairy cows. Although providing cows with some freedom of movement, these housing systems tend to be associated with high prevalence of lameness, although this probably results from the use of poorly designed stalls and hard, wet floors. Problems can also arise if stocking density is too high.

Figure 2 An example of tie-stall housing for dairy cows. Although tie-stalls appear to have some advantages in reducing competition between cows and in guaranteeing each cow a space to lie down, the restriction placed on their movement is difficult, if not impossible, to overcome through management. More recent research is also finding high levels of lameness and lesions of the legs and neck due to small, poorly designed stalls. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Housing and the welfare of dairy cattle

55

Figure 3 Deep-bedded straw packs probably provide one of the best methods of housing dairy cows indoors, based on the results of the European Food Safety Authority review. The cows have a comfortable lying area, comfortable places to stand and some freedom to move around. However, more labour is usually required to keep the areas clean, as the risk of mastitis is higher.

Given the public disquiet and the consequent move away from tethering and individual housing of pregnant pigs and veal calves, it is not surprising that the use of tie-stalls for cows is controversial, and a recent European Food Safety Authority (EFSA) opinion on the welfare aspects of cattle housing contained a minority opinion expressing concern about continued use of tie-stall housing (EFSA, 2009a). In theory, all types of housing have both advantages and disadvantages. Tie-stalls guarantee an animal a place to lie down, as well as easy access to food and water. However, tie-stall housing limits how much the animal can move and there is limited physical contact between animals. Loose housing overcomes the problem of mobility and allows physical contact between animals, but the animals are still housed in a restricted space and may need to compete for a lying area and for access to feed. A number of studies have tried to directly compare the welfare of lactating cows in these different systems. Recently, EFSA has published an extensive report on the welfare of dairy cows (EFSA, 2009a,b) that summarizes the research to date. Although the risk assessment was carried out separately for tie-stalls, free-stalls, straw yards and pasture, the report does provide us with a useful summary of the research into the effect of each type of housing on the welfare of the cows. Table 1 (taken from Rushen and de Passille, 2014) is a summary of the hazards identified in the EFSA report, and the magnitude of the adverse effect associated with each grouping of hazards for tie-stalls, free-stalls and straw yards. The hazards present in tie-stalls have a summed magnitude score slightly lower than the hazards in free-stalls but substantially higher than the score of the hazards in straw yards. Therefore tie-stalls represent a greater threat to animal welfare than straw yards but free-stalls are a slightly greater threat than tie-stalls. The most serious hazards facing cows in tie-stalls were those that resulted in behavioural problems, fear or pain. By contrast, straw yards did worse than tie-stalls in hazards leading to udder problems such as mastitis. The major disadvantages of free-stalls compared with tie-stalls are the hazards associated with housing, leading to leg and locomotor problems and metabolic and reproductive problems. The main advantages of straw-pack housing come from the fact that the magnitudes of these hazards are lower than those in free-stalls. This conclusion is supported by earlier data which tend to show that the occurrence of foot lesions and © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Housing and the welfare of dairy cattle Table 1 The number of hazards and the summed magnitude of the adverse effects of the hazards in each type of housing system for dairy cows that was identified by EFSA following a qualitative risk assessment. The magnitude of the hazard is calculated by multiplying the estimate of the severity of the hazard to welfare by its duration and multiplying this by the per cent of animals that are expected to suffer from the adverse consequences when they are exposed to the hazard. The numbers presented here are based on expert opinion Tie-stalls

Free-stalls

Straw yards

Leg and locomotor 22

29

24

Housing

493

710

335

Feeding

188

188

143

Management

315

338

330

Summed overall

996

1236

808

28

30

28

Housing

51

59

44

Feeding

3

3

3

55

62

130

109

124

177

48

54

51

Housing

239

542

245

Feeding

242

242

242

Management

120

193

122

Summed overall

601

977

609

43

49

44

Housing

1629

1321

662

Feeding

271

272

271

Management

150

224

208

2050

1817

1141

141

162

147

Housing

2412

2632

1286

Feeding

704

705

659

Management

640

817

790

3756

4154

2735

Number of hazards Summed magnitude of hazards

Udder problems Number of hazards Summed magnitude of hazards

Management Summed overall Metabolic and reproductive problems Number of hazards Summed magnitude of hazards

Behaviour, fear and pain Number of hazards Summed magnitude of hazards

Summed overall Total Number of hazards Summed magnitude of hazards

Summed overall

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Housing and the welfare of dairy cattle

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lameness is higher in free-stalls than in tie-stalls (Cramer et al., 2008; Sogstad et al., 2005) and in straw yards (Haskell et al., 2006). However, more recent epidemiological research has found a high prevalence of both lesions and lameness in tie-stall systems similar to the levels found in free-stalls (Charlton et al., 2016; Nash et al., 2016), which throws this conclusion into some doubt. One important question concerns the extent that the hazards associated with a particular housing system can be controlled through changes in management or whether they are an intrinsic part of the housing system and cannot easily be changed. In general, hazards associated with housing are more difficult for farmers to control than hazards associated with management and feeding. For example, according to the EFSA report, the largest hazard magnitudes for free-stalls resulted from having too few stalls for the number of cows (EFSA, 2009; Rushen and de Passille, 2014). However, this hazard can be managed relatively easily by reducing the number of cows. For tie-stalls, the biggest hazards involved the behavioural consequences of poor stall design, of inadequate bedding and of being tied without exercise. While the second may be managed by improving the management of bedding, reducing the first would require expensive changes to buildings (or buying smaller cows) while the third cannot really be managed at all. However, housing methods usually succeed or fail because of the details of the specific ways in which they are configured and managed, which makes it hazardous to generalize from any one farm to the housing system in general. A better approach is to examine the effects of the details of each housing system.

3  Stall design In both free-stall and tie-stall systems, the level of animal welfare will depend upon the design of the stalls provided to the animals. The effects of stall design are apparent in health measures, behavioural observations and measures of cow preference. Since lying

Figure 4 The duration of time that cows lie down can be measured automatically with accelerometers attached to the cow’s leg. The average herd lying time varies from farm to farm and is dependent upon the size of the stall and the amount and quality of bedding provided. This provides a simple method of assessing the degree of comfort of the cows (drawn from data presented in Charlton et al., 2016). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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stalls are the areas where cows are supposed to lie down, the quality of the design and management of the stalls can be assessed by measuring the duration of time that cows spend lying down in the stalls. The duration can be measured automatically and has been shown to vary greatly from farm to farm (e.g. Charlton et al., 2014; Ito et al., 2014; Solano et al., 2016) (Fig. 4). The general issues regarding the use of indicators of animal welfare have been discussed in Rushen et al. (2009).

3.1  Stall surface and bedding Since one of the main purposes of supplying a cow with a stall is to provide her with a place to lie down, an obvious concern is whether the surface of the stall is sufficiently comfortable, which will depend upon the base of the floor, and the quality and quantity of bedding used (Fig. 5). A serious concern is with the tendency for reduced use of bedding for dairy cows (EFSA, 2009a,b). Traditionally, cows were kept on abundant quantities of straw bedding and this is still frequently used in straw yards and in some free-stalls. The major advantage for cattle of straw bedding is that it does provide a warm, soft surface on which to rest (Tuyttens, 2005). In some places, however, straw is not easy or cheap to obtain and dairy farmers may use other forms of bedding, such as wood shavings, sawdust or sand. The marked increase in the incidence of mastitis has also led dairy farmers to become worried about any form of bedding that is composed of organic material that may harbour bacteria. The use of organic bedding tends to be associated with a higher incidence of clinical mastitis (e.g. Wagner-Storch et al., 2003), and, therefore, many farmers have become interested in inorganic bedding, such as sand. In some cases, farmers may dispense with bedding altogether and so the cows will be lying directly on the floor of the stall. In some cases, this will result in the cows lying on concrete, but the obvious problems with this option have led to the development of alternative, softer flooring surfaces including rubber mats, crumbled rubber-filled mattresses, and waterbeds. However, these alternative stall surfaces are often associated

Figure 5 Lying stalls that are too small for the cow to lie down comfortably, combined with too little bedding, contribute to some of the welfare problems associated with the use of free-stall housing and are some of the most important risk factors for a high prevalence of lameness and leg lesions. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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with reduced use of bedding. Insufficient bedding in both tie-stalls and free-stalls can increase the prevalence of teat damage, lower milk yield and reduce the longevity of the cows (Buenger et al., 2001; Rudd et al., 2010). Several large-scale epidemiological studies in North America have convincingly shown that absence of deep bedding in freestalls is a major risk factor for increased lameness as well as lesions to the hocks and knees (Husfeldt and Endres, 2012; Barrientos et al., 2013; Chapinal et al., 2013; Zaffino Heyerhoff et al., 2014; Solano et al., 2015) (Fig. 6). However, the relationship between lameness and uncomfortable stalls is complex. The risk for lameness increases if cows are not comfortable lying (Espejo and Endres, 2007; Dippel et al., 2009) since resting time is reduced and so cows spend more time standing. However, whether this will lead to lameness will depend upon what sorts of surfaces the cows are standing on. A series of experiments have shown that leg lesions are more prevalent on farms using geotextile mattresses than on those with deep-bedded stalls (Weary and Taszkun, 2000; Vokey et al., 2001; Zaffino Heyerhoff et al., 2014) or bedded packs (Livesey et al., 2002). Mattresses remain popular among many dairy producers, and research is required to identify improved methods of managing stalls with mattresses, so as to reduce the risk of injuries. For cows in tie-stalls, sole lesions and haemorrhages, as well as lesions to the front knees are more prevalent among cows housed in stalls with concrete floors than cows in stalls with rubber mats (Bergsten, 1994; Rushen et al., 2007). Swollen knees usually come from the physical impact as the cow lies down and stands up, while abrasions and hair loss result from friction with the stall flooring. Therefore, one advantage of softer stall flooring is in reducing the physical impact as well as the abrasiveness of the flooring. Furthermore, the act of lying down or standing up may be more difficult or more painful for cows kept on concrete with little bedding, as it leads to increased incidence of swelling of the front knees. Cows on softer mats showed an increased willingness both to lie down and to stand up (Rushen et al., 2007), and the cows that showed greater swelling of the

Figure 6 Lesions to the carpal joints (hocks) are a common welfare problem of cows in both tie-stalls and free-stalls. A lack of bedding, which is often found when geotextile mattresses are used, is one of the main risk factors. (Drawn from data presented in Zaffino-Heyerhoff et al., 2014). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Housing and the welfare of dairy cattle

front knees lay down for shorter periods of time than those with less swelling of the knees, suggesting that reduced physical impact on the front knees may be equally or more important (Rushen et al., 2007). Dairy cattle show clear preferences for softer stall surfaces. For example, cows will preferentially lie down on deeply bedded surfaces with either sawdust or sand rather than mattresses with little bedding (Tucker et al., 2003), and prefer heavily bedded stalls to lightly bedded mats, or solid surfaces like concrete, mats or wood (Wagner-Storch et al., 2003). Furthermore, cows spend more time lying down, and they lie down more often on softer and/or well-bedded surfaces (Tucker and Weary 2004; Haley et al., 2000; Ito et al., 2009, 2014; Solano et al., 2016). Lame cows in particular prefer to lie down in deep bedding (Jensen et al., 2015). Although cows may find deep straw bedding more comfortable than sand (Norring et al., 2010), in general, the research suggests that sand bedding is the best option for reducing mastitis, lameness and leg lesions, while providing a sufficiently comfortable material for lying stalls (e.g. van Gastelen et al., 2011). Clearly, inadequate bedding is an issue for both tie-stalls and free-stall, with the most obvious consequence being reduced time spent lying down. Whether the risk of lameness will also be increased will depend upon the surface on which the cows are standing in passageways and at the feeders (Section 4). Use of adequate bedding may also have unexpected benefits: Campler et al. (2015) found that cows bedded previously on deep straw calved more quickly than those housed in free-stalls.

3.2  Stall size and configuration The size of the lying stalls provided to cattle differs in many ways, which include the width between partitions, the shape of stall partitions, the length of the bed, the amount of lunge space, the height of the curb at the rear of the stall, the height and shape of the barrier (‘brisket board’) used to keep the cow in the stall, and the height of the neck rail and its position relative to the stall curb. For each of these features there is a wide range of recommended specifications, which are largely based on the personal experience of dairy professionals. Importantly, these dimensions need to be expressed as a function of the size of the cow that is likely to occupy the stall. For example, Anderson (2008a,b) recommends that the bed length be 1.2 times the height of the cow at the rump, while the width of the stall be twice the width of the cow at the hook bone. However, many dairy farms do not follow these recommendations (e.g. Nash et al., 2016). Recent research has Table 2 Recommendations for tie-stall sizes as a function of the size of the cow

1

Dimension

Recommendation1

Stall width

2 X width of the cow at the hook bone

Bed length

1.2 X height of cow at rump

Tie rail height

0.80 X height of cow at rump

Tie rail position

35 cm more than stall length, from the back of the stall

Chain length

Height of tie rail – 20 cm

Manger wall height

500 000 observations per year since 1970. In 2014, US phenotypic daughter pregnancy rates appear to have reached the same levels as the early 1980s, as with Ireland and Australia the lowest point for the genetic trends was in the 2000s. Interestingly, improvements in reproductive performance started before the introduction of fertility breeding values in the United States (in 2003), which could have been because of (1) selection on other correlated traits, such as longevity (VanRaden et al. 2004); (2) widespread use of bulls that had positive fertility breeding values (even if this was not known); or (3) more aggressive culling for poor fertility. As a final note to this section, valuable lessons have been learnt by dairy geneticists and sire analysts in the dangers of narrow breeding goals. However, it appears that tangible improvements in fertility are now being achieved. In addition to sustaining selection on fertility, welfare and disease resistance traits in particular are becoming key areas where breeding values are being developed for future breeding goals.

4  New breeding objectives: health traits In their review of more than 1600 citations, Kelton et al. (1998) identified eight diseases that had a high economic impact and a large number of cows affected by these diseases (e.g. milk fever, retained placenta, metritis, ketosis, left displaced abomasum, cystic ovarian disease, lameness and clinical mastitis). To be able to reduce disease incidence through breeding, appropriate ways of measuring the traits need to be devised (so-called selection criteria), this can be either measurements of the trait itself (the breeding objective) or traits that are correlated to the breeding objective. In 1988, the first major review of data recording opportunities and consequently breeding strategies to improve production diseases was published (Emanuelson 1988). However, quite a lot has changed since then. Notably, computerised farm recording has led to a large increase in data available on these traits (and their predictors) and consequently studies on genetic parameter and breeding value estimation. In fact, several countries around the world have implemented routine genetic evaluations of health traits using (predominantly) farm-recorded clinical records of disease observations (Egger-Danner et al. 2015). However, there are examples where disease resistance has been selected for indirectly, notably for mastitis.

4.1 Mastitis 4.1.1  Alternative cell count traits One of the most important diseases in dairy production is mastitis. A common selection criterion, where the breeding goal is to improve mastitis resistance, is selection for reduced SCC. Cell count can be quantified from routinely assessed milk samples and are available to all farmers participating in milk recording to make management decisions. As a by-product of national recording schemes, breeding values for SCC are routinely calculated by many national breeding organisations. The genetic correlation of SCC with mastitis is around 0.7 (Mrode and Swanson 1996), making selection for reduced SCC a convenient way to reduce the incidence of cases of clinical mastitis. The power of using SCC breeding values to reduce the occurrence of clinical mastitis has recently been shown in an Australian study by Abdelsayed et al. (2016; unpublished). In this study, top versus © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Genetic selection for dairy cow welfare and resilience to climate change 87

bottom 10% for breeding values of SCC of around 2000 sires with at least 10 cow lactations had a 6.3% difference in the percentage of recorded cases of clinical mastitis (Fig. 2). However, several studies have shown that selection for directly reducing the number of cases of mastitis is likely to be more effective than relying solely on predictor traits (such as SCC) (Heringstad et al. 2006; Gaddis et al. 2014; Egger-Danner et al. 2015). The Nordic countries have a long history of recording health traits, for example in Norway veterinary treatments had to be registered on an individual basis from 1975 (Heringstad and Østerås 2013), with similar recording being established in Denmark, Finland and Sweden during the 1980s. In addition to the Nordic countries, routine genetic evaluations of mastitis have been in place in Austria and Germany since 2010, and in France and Canada from 2012 (Egger-Danner et al. 2015). Results from a Norwegian selection experiment have shown that a reduction in the incidence of mastitis is achievable if there is sufficient selection pressure in the breeding objective. Heringstad et al. (2007) demonstrated that after five generations of selection, a 4% difference in clinical mastitis was observed between two lines of Norwegian Red Cattle that were selected for either high protein yield or mastitis resistance, using breeding values calculated with records of clinical mastitis. As most countries still do not have their health-recording schemes in place yet, several countries have started to look at alternative cell count traits as predictors of clinical (CM) and sub-clinical cases of mastitis (SCM). Alternative SCC traits have been suggested, where test-day records for SCC were either analysed individually (Heuven 1987; Reents et al. 1995) or were described on a lactation level (Detilleux et al. 1997; Schepers et al. 1997; de Haas et al. 2003; Green et al. 2004). Examples of suggested traits are (1) proportions of test-day SCC above or below certain thresholds, (2) directions and rates of change

Figure 2 Percentage of recorded cases of clinical mastitis in around 2000 sires that are divergent for Australian national genetic evaluations of somatic cell count breeding values.

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Genetic selection for dairy cow welfare and resilience to climate change

in test-day SCC, (3) number of days until SCC reaches an upper or lower threshold, (4) differences between observed SCC and SCC expected under healthy conditions, (5) areas under (parts of) the lactation curve of SCC, (6) standard deviation of log test-day SCC during lactation, (7) rolling SCC averages and (8) peaks in SCC. Windig et al. (2010) examined which combination of alternative SCC traits can be used best to reduce both CM and SCM. Their conclusion was that a combination of five SCC traits (i.e. average SCC in early (5–150d) and late (>150d) lactation, suspicion of infection based on increased SCC, extent of increased SCC and presence of a peak pattern in SCC) gave a high accuracy of 0.91, when the aim was to reduce CM directly. Using a set of SCC traits can, therefore, partly overcome absence of direct observations on CM. In fact, direct observations on CM add little to the accuracy of an index if five SCC traits are used. To conclude, the urgency to set up a full infrastructure to collect data on CM is not essential to achieving acceptable rates of genetic improvement in mastitis resistance. In the Netherlands, an udder health index based on a combination of alternative SCC traits was introduced in 2010 (Eding and de Jong 2010). In Ireland, a similar index will be introduced in 2016. In addition to SCC, other predictors of clinical mastitis could be used to increase the accuracy of breeding values. Examples include udder conformation (Lund et al. 1994), electrical conductivity from automated milking systems (Norberg 2005) and lactate dehydrogenase, which is a potential biomarker for mastitis (Friggens et al. 2007b). Norberg (2005) had reservations on practical aspects of data collation of electrical conductivity, but also illustrated that it could be used in breeding programmes. Electrical conductivity requires specialist machinery to evaluate, whereas SCC and lactate dehydrogenase have to be analysed by laboratories.

4.1.2  Recovery from mastitis The studies described so far have investigated the transition probability of developing mastitis, but none of them have focused on the probability of recovering from an infection. Franzen et al. (2012) presented an alternative longitudinal approach in which evaluation of mastitis is performed based on changes in SCC during lactation; these changes are captured by modelling transition probabilities between assumed states of mastitis and non-mastitis. The method simultaneously models the transition probability of developing mastitis and the probability of recovering from an infection. In their approach, Franzen et al. (2012) modelled both aspects to capture as much information as possible from the SCC lactation pattern. The model did indeed capture the dynamic nature of the disease by modelling mastitis liability and by including the recovery process and repeated cases into the analysis, and the results point towards a significant gain by including the whole disease course. One way to improve the model of Franzen et al. (2012) is to describe the fluctuating behaviour of SCC in milk in an online monitoring tool with a Bayesian approach to time series analysis (West and Harrison 1997). It is based on recursive parameter estimation, adaptive filtering for online (short-term) forecasting and offline retrospective analysis afterwards (backward smoothing) and change detection, followed by automatic intervention. André (2011) took the Bayesian approach to develop adaptive (self-learning) dynamic models for operational use in dairy farming. This method will be able to describe fast (fluctuations around the level) and slow (changes in level itself) fluctuations of the SCC in milk, depending on the frequency of SCC sampling. Frequent sampling will, however, require a more advanced model. These © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Genetic selection for dairy cow welfare and resilience to climate change 89

dynamic linear models can be used to describe individual SCC patterns and are able to detect process disturbances, such as (sub)clinical mastitis based on the SCC. It will help to detect a change in SCC level, and will simultaneously predict if a cow is capable of reducing SCC to her expected level after SCC increase, or if she needs treatment with antibiotics to combat the infection.

4.2 Lameness While mastitis is the most common disease in dairy cattle, there are other diseases that should be considered as candidates for genetic improvement. After mastitis, the next most common welfare problem in dairy cattle is usually considered to be lameness, which is a major health and welfare issue for dairy cattle worldwide, and feet and leg issues are common reasons for culling in dairy cattle (Egger-Danner et al. 2015). Lameness results in increased veterinary costs, higher culling rates, reduced fertility and economic costs due to lower milk production and loss of body condition and live weight (Chawala et al. 2013). In Ireland, an overall incidence of 15% is assumed, of which 3% require veterinary intervention with associated higher costs (Berry and Amer 2005). Several studies have shown that lameness is heritable, with heritability estimates ranging from 0.07 to 0.10 reviewed by Kougioumtzis et al. (2014). Although the heritabilities are low, reduced lameness may be achieved by breeding for improved claw health. Clinical records on lameness are not always present, and selection to reduce lameness has historically focused on conformation of feet of legs, as this is routinely recorded by breed societies and many countries already calculate breeding values for these traits. However, the accuracy of breeding values for claw health or resistance to lameness increased when claw health data is included (Koenig et al. 2005). A preliminary study in Ireland showed that there is a great benefit if direct information on lameness records is added to an index to predict lameness in addition to conformation traits. One way of accessing large amounts of clinical lameness data is to work with professional hoof trimmers who have expertise in diagnosis of claw disorders. An example has been developed by CRV (Arnhem, the Netherlands), who have set up a system, called DigiClaw (http://www.slideserve.com/mannix-sanford/implementation-of-a-claw-health-index-in-thenetherlands) together with the Animal Health Service in the Netherlands. Another promising approach is to develop breeding values for different types of lameness, as there is evidence to suggest that heritabilities vary among claw diseases recorded by hoof trimmers (Buch et al. 2011; Ødegård et al. 2013). To do this on a level that is large enough for breeding value development (e.g. national) requires accurate and consistent data records. In fact, there has been a lot of effort recently to harmonise recording of claw disorder, for example the ICAR claw health atlas (Egger-Danner et al. 2014). Another option is to use locomotion scores that vary between normal gait and severely lame, which can be evaluated on all cows, but are usually only available once in lactation (Boelling and Pollott 1998).

4.3  Metabolic diseases Metabolic disorders such as ketosis, displaced abomasum, milk fever and tetany are disturbances to one or more of the metabolic processes in dairy cattle. Intense selection for production has led to a reliance on body reserves to support early lactation. Consequently, the commencement of lactation and some of the remainder of lactation are often in negative energy balance. This leads to an imbalance in hormones and metabolites giving © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Genetic selection for dairy cow welfare and resilience to climate change

rise to metabolic diseases (White 2015). Dysfunction or imbalance in metabolic processes leads to disease, so it is not surprising that genetic correlations between many dairy cow production diseases and milk production traits are mostly unfavourable (e.g. Uribe et al. 1995; Pryce et al. 1997; Zwald et al. 2004). Usable genetic variation in metabolic stability implies that breeding should be considered as a way to achieve improvements. Under-recording and difficulty in diagnosing sub-clinical cases are among the reasons why there is growing interest in using easily measurable predictors of metabolic diseases, either recorded ‘on-farm’ by using sensors and milk tests or recorded ‘off-farm’ using data collected from routine milk recording. Some countries have already initiated genetic evaluations of metabolic diseases (e.g. the Nordic countries and Austria/Germany) and these evaluations are based on clinical observations of disease.

4.4  Mid-infrared spectral data One of the most promising ways of evaluating sub-clinical disease is the mid-infrared (MIR) analysis of milk samples. In addition to traditional traits (i.e. fat, protein, casein, lactose and urea contents), MIR analysis of milk has been used to predict other milk characteristics such as fatty acid composition, milk protein composition, milk coagulation properties, milk acidity, mineral composition and ketone bodies (De Marchi et al. 2014). For some of these traits such as ketone bodies, the accuracy of prediction is not high enough to use MIR predicted values as a reference value. However, the accuracy is sufficient for a rough screening to distinguish cows with high or low values. Hence, MIR may be an opportunity to massively increase the number of phenotypic records available for sub-clinical diseases, as MIR is used in standard milk analysis undertaken by milk recording organisations. As with metabolic disease biomarkers, there is growing evidence that MIR can also be used to predict energy balance (McParland et al. 2014), which can be explained because catabolism of stored adipose reserves during body condition score change results in an increase in C18 fatty acid concentration in milk (Berry et al. 2013). Already there are several papers clearly showing that MIR can be used to predict the concentration of several fatty acids (Soyeurt et al. 2006; De Marchi et al. 2014) and might therefore mirror body condition score changes.

4.5  General disease resistance Another appealing strategy is to select for more general immunity to diseases. Heringstad et al. (2007) showed that selection against mastitis leads to favourable correlated responses to selection in other diseases, such as ketosis and retained placenta, indicating the existence of a general robustness or reduced liability to disease. Furthermore, in a study by De la Paz (2008) it was reported that cows with both high antibody and cellmediated immune response have a decreased risk of disease occurrence for several diseases, including mastitis, ketosis, metritis and retained placenta, compared with cows identified as low responders. The heritability of response to an immunity challenge is high enough to justify selection (Thompson-Crispi et al. 2012b). In fact, selection tools for immunity are available commercially. Semex (www.semex.com) sells semen from bulls identified as being high and low antibody and cell-mediated responders to an immune challenge. The high responders were found to have half the disease occurrence compared with low responders (Thompson-Crispi et al. 2012a).

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Genetic selection for dairy cow welfare and resilience to climate change 91

5 New breeding objectives: dairy cows and climate change Climate change is a growing international concern and it is well established that the release of greenhouse gases (GHG) is a contributing factor. At the recent Conference of Parties in Paris 2015 (www.cop21paris.org), many countries committed themselves to reduce their GHG emissions by 30% by year 2030 relative to 1990 levels. The global livestock sector, particularly ruminants, contributes approximately 18% of total anthropogenic GHG emissions (Steinfeld et al. 2006). Although mitigating the impact of ruminants on GHG emissions is not a welfare problem itself, the impacts of climate change on livestock poses a threat. Consequently, steps need to be taken to (1) reduce GHG emissions and (2) improve adaptability of cattle to climate change as a result of increased GHG emissions.

5.1  Greenhouse gas emissions Enteric methane is produced as a by-product of anaerobic fermentation (methanogenesis) in the digestive tract by microorganisms called methanogens. Considering that milk production traits are a large part of the breeding goal, the GHG emitted per litre of milk are diluted in higher yielding cows. Consequently, it is worthwhile quantifying the impact of current selection on mitigation of GHG emissions. We estimate that under current rates of genetic gain in Australia, the amount of milk solids (fat plus protein) produced per cow will increase by 1.92 kg/year through selection and therefore we project that milk solids’ yields will increase from 501 kg/cow/year to 520 kg/cow/year. If all cows in the current population (assumed to be 1.7 million) improve their yields by this amount then we estimate that approximately 60 000 fewer cows would be required to produce the same amount of milk solids. This is equivalent to a reduction of 397 383 t CO2-eq. The second area of improvement is the reduction in emissions per unit of milk solids, that is, a dilution effect on emissions of having more productive cows of 33.62 gCO2/kgMS/year, which is equivalent to 293 096 t CO2-eq. After 10 years, the total annual impact of dairy selection practices on GHG emissions is projected to be 397 383 + 293 096 = 640 483 t/year, which is about 4.6% of the total current annual dairy emissions of 14 900 000 t/ year. Selecting on other traits that improve the efficiency of farm systems, for example, milk yield, residual feed intake and longevity will also have a favourable effect on overall emissions (Wall et al. 2010). Additional benefits could be achieved in reducing methane emissions if breeding values for methane emissions could be developed. However, building a sufficiently large dataset for genetic parameter estimation has been challenging, as phenotype data is scarce. New methods of detecting methane emissions are being developed, including gas sensors and radioactive tracers (SF6), which will enable enough phenotypes to be collected to estimate genetic parameters. For example, using a portable air sampler and analyser unit to measure methane emissions on 3121 cows from 20 herds, Lassen and Løvendahl (2016) estimated that the heritability of methane emissions varied between 0.16 (s.e. 0.04) and 0.21 (s.e. 0.06) for various methane emission traits. Including methane emissions in the selection objective may further reduce greenhouse gas emissions at a small economic cost.

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5.2  Heat tolerance Animals have a comfort zone where body heat is effectively dissipated and the physiological state is maintained. When environmental parameters (e.g. temperature, humidity, radiation, solar and wind speed) go beyond this thermo-neutral zone (threshold), animals will start to experience heat load; if this becomes acute, heat stress will occur. Inability of animals to regulate body temperature under heat stress can result in loss of production, decrease in feed efficiency, suppression of immune system leading to increased susceptibility to diseases and decreased fertility (De Rensis and Scaramuzzi 2003). Differences in ability to cope with heat stress are influenced by several factors varying from animal characteristics (e.g. age, level of production) and physical properties (e.g. size, skin, coat) to environmental and herd management (e.g. feeding, housing, heat duration and abatement techniques). The ability to cope with heat stress varies among breeds: Holsteins appear to exhibit greater reductions in milk yield in hotter climates than Jerseys or cross-breeds (Bryant et al. 2007). In fact, reductions in yield start when temperatures exceed 21 and 25°C at 75% humidity for Holsteins and Jerseys, respectively (Bryant et al. 2007). Nguyen et al. (2016) used a similar approach to calculate genetic parameters for heat tolerance and estimated that the heritability of heat tolerance was around 0.11.

6  Genomic selection, inbreeding and gene editing 6.1  Genomic selection There are very few examples where the price of a commodity has dropped as dramatically as genotyping. In 2001, the first human being was sequenced at a price of US$3 billion (Venter et al. 2001). Since then, the $1000 genome has become a bit of a catchphrase and is now a reality. One of the biggest successes in agricultural science in recent years has been to leverage off investment made in medical genetics and applying it to make smart new ways to select the best individuals for the next generation. Sequencing of bulls (key ancestors of dairy and beef breeds) is now happening around the world, with the 1000 Bulls Genome Project comfortably exceeding that target and offering new insights into genetic architecture in addition to increasing the accuracy of genomic prediction of many other traits, by providing more informative genetic markers to use in genomic selection (Daetwyler et al. 2014). Genomic selection refers to selection decisions based on genomic breeding values (Meuwissen et al. 2001). The way it works is that a genomic reference population is assembled, typically genotyped bulls with large numbers of progeny. A genomic prediction equation is then calculated from the reference population by looking for associations between phenotypes and dense genetic markers that are approximately equally spaced across the entire genome. In cattle a variety of marker panels are used, varying from a few thousand genetic markers per panel to hundreds of thousands. The genomic breeding values are calculated as the sum of each of the genotypes multiplied by its respective effect on a trait, thereby potentially capturing most of the genes that cause differences among animals in the traits of interest. This prediction equation can then be applied to individuals that are genotyped, but have no phenotypes. Therefore, the genetic merit of an individual can be calculated as early as birth and, therefore, selection decisions can be made earlier in life than traditional progeny-test approaches. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Genetic selection for dairy cow welfare and resilience to climate change 93

Genomic selection is now used routinely in many countries for genetic evaluation of traits that already have an estimated breeding value derived from a combination of pedigree and phenotype information (Spelman et al. 2013). The advantage of genomic selection for these traits is that the rate of genetic gain is accelerated by 40–50% (Spelman et al. 2013). To date, there have been limited attempts to calculate genomic predictions for health traits; countries that include genomic information in their genetic prediction of health disorders include Canada, France and Scandinavia. Other countries, such as the United States are at the time of writing in the research phase, but have found that genomic information improves the accuracy of prediction. Genomic reference populations may assist with difficult-to-measure traits, such as health, as efforts to record and evaluate these traits can happen in a small reference population and the benefits used by the entire population, that is, prediction equations are based on cows in the reference population that have phenotypes on a range of traits, possibly also including health traits. For cheap and easy to measure phenotypes, reasonable reliabilities can be achieved using reference populations comprising genotyped bulls with progeny groups. For traits that are expensive to measure, or where data is sparse, the best option is to obtain phenotypes on genotyped cows (Chesnais et al. 2016). In some circumstances, adding females to the reference population can be advantageous for traits that are measured on a large (national) scale, for example, production, longevity and fertility. It appears that the biggest gains are made when the genotyped females comprise a high percentage of the overall reference population and where the cows are selected based on very-high-quality phenotypes. An example of adding females to the reference population is the Australian Ginfo population of around 25 000 Holsteins, Jerseys and cross-bred cows from 100 herds that were selected based on objective criteria around recording quality. By adding the Ginfo cows to the reference population, the size of the total Holstein and Jersey reference populations increased by 44% and 38%, respectively. The reliability of the BPI increased by 5.8% in Holstein genotyped animals; the reliability of fertility breeding values improved by 4/5% and overall type improved by 7.1% (ADHIS, 2016; unpublished results). These are substantial improvements and pave the way for extending the number of traits evaluated, as the future Ginfo population is expected to be a rich resource in phenotypes for ‘new’ traits. The next step in future genomic evaluations is to use information from biological priors to further improve the accuracy of selection. Genome-wide association studies (GWAS) are often used to identify regions of the genome that have a specific impact on a trait of economic importance. Sometimes these can be linked to candidate genes, which helps our understanding of the genetic control of complex traits and if large enough, can also be selected on directly. GWAS have already been used to identify parts of the genome with large effect on fertility and some promising candidate genes have been identified (Sahana et al. 2010; Pimentel et al. 2011). Whole-genome sequencing is likely to improve the resolution and detection of causative mutations of these candidate SNPs. While new mutations are likely to be identified, the challenge will be to apply this knowledge. One option is to use this as prior information in genomic selection methods. There are examples where this has been tested and increases in accuracy of prediction achieved. For example, Khansefid et al. (2014) found that placing more emphasis on SNP associated with residual feed intake in beef cattle increased the accuracy of genomic prediction in dairy cattle. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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6.2 Inbreeding Recording of ancestry has been the cornerstone of genetic improvement programmes in livestock, with breeding decisions historically being made on breeding values estimated using a combination of pedigree and phenotype data. Extensive use of artificial insemination and very similar worldwide selection objectives has led to intense selection of superior males to become sires of the next generation. Therefore, it is almost impossible to find dairy animals without genetic ties to certain key ancestor bulls. This has led to an increase in inbreeding reported in most dairy populations (Miglior et al. 1995; Wiggans et al. 1995; VanRaden et al. 2011). Another use of genomic data is to monitor inbreeding in a population by quantifying genomic relationships between animals (Pryce et al. 2012). Inbreeding arises in individuals that have parents that share a common ancestor, which is known as identity by descent. Pedigree is commonly used to assess the inbreeding of the individual itself and its relationship to others in the population. As inbreeding increases, regions of the genome become more homozygous and also increases the risk of homozygous lethal recessives. There are examples of genetic diseases that are lethal recessives, such as CVM, BLAD and DUMPS in Holsteins. Most of these diseases are the result of reasonably recent (rare) mutations. For example complex vertebral malformation, or CVM, can be traced to two former elite Holstein sires; as a result of their widespread use, the sires appeared on both sides of the pedigree of affected calves (Agerholm et al. 2001). Conditions such as these diseases highlight the importance of managing rates of inbreeding, which arises as a result of the co-occurrence of common ancestor(s) in maternal and paternal pedigrees. An example of identity by descent is shown in Fig. 3.

Figure 3 A case study in the use of genomics to identify homozygosity and identity by descent. The individual (progeny) that results from the mating of the sire and dam is inbred, as the grand-sire on either side of the pedigree is the same animal (shown in yellow). If the genomic regions from the grandsire are tracked from generation to generation, the segments that are proportion of homozygous can be quantified. If the grand-sire is a carrier of a lethal recessive, the progeny will be affected if it inherits both copies of the recessive.

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6.3  Gene editing An opportunity to use genetics to improve animal welfare is through new technologies, such as gene editing. Gene-editing techniques can be used to precisely alter the genome through inserting, editing or DNA sequencing (Hsu et al. 2014). Gene editing makes it possible to change or disable a single gene without changing the ‘meaning’ of the rest of the genome. This means that undesired effects such as accidentally turning off a useful gene are less likely than with previous genome modification techniques and the desired gene can be introduced rapidly into a population. However, there are regulation issues associated with applying gene editing to livestock that need to be dealt with before marketable applications are made. Provided the regulation issues can be overcome, there are many applications that could have major implications for animal welfare. Here, we will provide three examples that impact on animal welfare in quite different ways: the first example is introgression of the polled gene (hornless cattle), the second example is the cholesterol deficiency mutation associated with juvenile mortality and the third is the Slick gene for improved heat tolerance. Many of the traits that we deal with in animal breeding are polygenic in their genetic control. This means that the genetic architecture is often complex, involving many loci. Although it may be obvious that quantitative traits, such as height or weight are controlled by multiple loci, many diseases are also complex in their genetic architecture. Although we have given examples of single genes that can be edited, multiple sites can be edited simultaneously (Hickey et al. 2016).

6.3.1  Polled gene Most dairy heifers are disbudded or dehorned at an early age. The procedure is generally done using heat cauterisation, often without the use of anaesthetic and is therefore considered an animal welfare issue. The gene for polled is a single dominant gene. Therefore, mating a homozygous polled bull (PP) to a herd of non-polled cows (hh) will result in all the offspring being polled (Ph). If the bull is heterozygous (Ph) and the cows are horned (hh), half the offspring will be polled (Ph). Two mutations that prevent development of horns in certain breeds of cattle have been mapped on the bovine genome (Medugorac et al. 2012). Genetic dehorning of cattle would certainly be preferable, however, introgression of the polled gene through conventional selection would lead to a trade-off in genetic merit, as carriers of the polled mutation are generally inferior in genetic merit, recovery of genetic merit could take several generations. Gene editing is an obvious solution and a method to do this using the gene-editing technique called transcription activator-like effector nucleases has already been used to generate live polled calves (Fahrenkrug and Carlson 2014).The advantage with this method is that no additional genetic material is transferred between breeds.

6.3.2  Cholesterol deficiency In 2015, a new defect was discovered in Holsteins by Kipp et al. (2015) at VIT in Germany that causes young calves to die if homozygous. They concluded that heterozygous animals have reduced cholesterol, but homozygotes have no cholesterol and survive only a few months. The defective haplotype traces back to one sire born in 1991 (https://www.cdcb. us/reference/changes/HCD_inheritance.pdf). This indicates that animals that have this sire in their pedigree more than two times might be carriers of this defect (see Fig 3). Through

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the availability of genomic information, this defect is known, but it also provides a basis for genome-assisted approaches to avoiding inadvertent carrier matings.

6.3.3  Slick gene As mentioned earlier in this chapter, heat stress is a big problem for the lactating cow. One approach for improving resistance to heat stress in dairy breeds is to introduce thermotolerance genes from other breeds. One such gene is called the slick gene. The slick is described as a very short, sleek hair coat mostly observed in tropical Bos taurus cattle of Criollo descent (Huson et al. 2014). Slick cattle are better able to regulate body temperature during heat stress than cows with normal hair (Dikmen et al. 2014).

7 Summary Genetic selection has led to phenomenal rates of genetic gain in milk production traits. However, from the mid-1990s, it was recognised that narrow breeding goals, focused on production traits, had negative consequences for fitness traits, impacting on animal welfare. The most obvious was the deterioration in female fertility, which has been observed worldwide. Since then, breeding goals have been extended and realised selection responses for traits such as fertility show that genetic selection can improve even low heritability traits. More recently, there has been a surge of interest in selecting for health traits and traits associated with resources, such as feed efficiency and methane emissions, even though the collection of these phenotypes may be expensive and only possible in small populations. In fact, all these traits are ideal candidates for genomic selection where the basic requirement is a population that has genotypes and phenotypes (either on the individual or on its progeny). Genotypes and associated phenotypes are used to create a reference population to calculate genomic prediction equations that can be applied to cows or bulls that are genotyped but do not have phenotypes. While genomic selection has been implemented for many traits (production, fertility, cell count, longevity, etc.), there are still obstacles in applying it to several new traits, associated with the heritability of the trait, the number of animals in the reference population and the cost of phenotyping. The opportunities to apply genomic selection to traits related to welfare are abundant and include common health disorders, such as mastitis resistance, lameness and ketosis. One option is to customise future breeding goals to include appropriate traits for the prevailing management and environmental conditions. For example, selection for heat tolerance is of great importance in emerging (and many existing) dairy regions. In conclusion, genomic selection offers exciting prospects for genetically improving scarce and expensive to measure traits, such as those associated with dairy welfare and resource usage.

8  Where to look for further information Many new and relevant journal articles are published by the Journal of Dairy Science (JDS) including a recent collection of papers on balanced breeding: http://www. journalofdairyscience.org/content/balancedbreeding. Also Interbull has annual meetings and freely provides the latest finding and discussions: http://www.interbull.org. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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9 Acknowledgements Jennie Pryce acknowledges the Gardiner Foundation (Melbourne, Australia) for financial support through the ImProving Herds project. We acknowledge Professor Ben Hayes (University of Queensland) and Dr Matthew Bell (University of Nottingham) for their contribution to the sections on adaptability to climate change. We also thank Dr Mary Abdelsayed (Holstein Australia, Melbourne) for providing us with unpublished data contributing to Fig. 2.

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Genetic selection for dairy cow welfare and resilience to climate change 101 Uribe, H., Kennedy, B., Martin, S. and Kelton, D. (1995), Genetic parameters for common health disorders of Holstein cows. Journal of Dairy Science 78, 421–30. VanRaden, P. (2004), Invited review: selection on net merit to improve lifetime profit. Journal of Dairy Science 87, 3125–31. VanRaden, P., Sanders, A., Tooker, M., Miller, R., Norman, H., Kuhn, M. and Wiggans, G. (2004), Development of a national genetic evaluation for cow fertility. Journal of Dairy Science 87, 2285–92. VanRaden, P. M., Olson, K. M., Wiggans, G. R., Cole, J. B. and Tooker, M. E. (2011), Genomic inbreeding and relationships among Holsteins, Jerseys, and Brown Swiss. Journal of Dairy Science 94, 5673–82. Veerkamp, R. (1998), Selection for economic efficiency of dairy cattle using information on live weight and feed intake: a review. Journal of Dairy Science 81, 1109–19. Veerkamp, R., Beerda, B. and Van der Lende, T. (2003), Effects of genetic selection for milk yield on energy balance, levels of hormones, and metabolites in lactating cattle, and possible links to reduced fertility. Livestock Production Science 83, 257–75. Venter, J. C., Adams, M. D., Myers, E. W., Li, P. W., Mural, R. J., Sutton, G. G., Smith, H. O., Yandell, M., Evans, C. A. and Holt, R. A. (2001), The sequence of the human genome. Science 291, 1304–51. Wall, E., Simm, G. and Moran, D. (2010), Developing breeding schemes to assist mitigation of greenhouse gas emissions. Animal 4, 366–76. West, M. and Harrison, J. (1997), Bayesian Forecasting and Dynamic Models. Springer-Verlag, New York, US. White, H. M. (2015), The role of TCA cycle anaplerosis in ketosis and fatty liver in periparturient dairy cows. Animals 5, 793–802. Wiggans, G. R., VanRaden, P. M. and Zuurbier, J. (1995), Calculation and use of inbreeding coefficients for genetic evaluation of United States dairy cattle. Journal of Dairy Science 78, 1584–90. Windig, J. J., Ouweltjes, W., ten Napel, J., de Jong, G., Veerkamp, R. F. and De Haas, Y. (2010), Combining somatic cell count traits for optimal selection against mastitis. Journal of Dairy Science 93, 1690–701. Zwald, N., Weigel, K., Chang, Y., Welper, R. and Clay, J. (2004), Genetic selection for health traits using producer-recorded data. I. Incidence rates, heritability estimates, and sire breeding values. Journal of Dairy Science 87, 4287–94.

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Chapter 5 Ensuring the welfare of culled dairy cows during transport and slaughter Carmen Gallo and Ana Strappini, Animal Welfare Programme, Faculty of Veterinary Science, Universidad Austral de Chile, Chile 1 Introduction 2 Legislation and codes of practice 3 Pre-transport conditions that influence the welfare of cows during transport 4 Welfare of culled cows during transport 5 The effects of livestock markets on cow welfare 6 Welfare of cows at the slaughter plant 7 Conclusions 8 Where to look for further information 9 References

1 Introduction Culling is the departure of cows from the herd because of sale, slaughter, salvage or death (Fetrow et al., 2005). The proportion of cows that are culled from dairy herds annually is variable (25–30%), and depends on biological factors such as age, parity, milk yield, reproductive and sanitary state of the cows, and also on economic factors such as the price of milk, of cows and replacement heifers (Bascom and Young, 1998). Most of the culled cows will be either sold through livestock markets and livestock dealers or sent directly to slaughterhouses. According to the studies of González et al. (2012a,b,c) in cattle submitted to long haul in North America, for all loads of different categories surveyed, culled cattle represented only 0.9%. In Chile, Gallo et al. (1999) registered the different categories of cattle arriving at several Chilean slaughterhouses, finding that adult and old cows represented around 15% of all cattle slaughtered; most of these cows were actually slaughtered at the smallest, and not exporting, meat plants. Another survey in Chile described 413 transport loads arriving at slaughterhouses and showed that 9.4% of them were culled cows (Gallo et al., 2005). Clearly, the number of culled cows slaughtered yearly in each country is variable and will depend mostly on economic factors, but their proportion with regard to the total of all cattle categories slaughtered is rather low. However, the sale of market cows and bulls accounts for 25% of all U.S. beef consumption (U.S., 2007). Culled cows are part of the food supply chain and should be http://dx.doi.org/10.19103/AS.2016.0006.05 © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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treated accordingly to provide meat that is acceptable from a meat safety and quality point of view, as well as from an ethical point of view that considers animal welfare. Good handling during transport and slaughter aims to achieve that.

2  Legislation and codes of practice Risks during transport can be reduced by selecting animals best suited to cope with the ordeals of journey. Therefore, the World Organisation for Animal Health standards (OIE, 2015) state that each animal should be inspected in order to evaluate fitness for transport and those that are considered unfit for transport should not be loaded, unless they are sent for veterinary treatment. Among animals unfit for transport are those sick, injured, weak, disabled or fatigued; those that are unable to stand unaided or cannot be moved without causing them additional suffering; those whose physical condition would result in poor welfare; females travelling without their young ones, that is, females that have given birth within the previous 48 h and pregnant animals that would be in the final 10% of their gestation period at the planned time of unloading. In accordance with OIE standards, all revised legislation/codes of practice (USA, 2003; European Council, 2005; New Zealand, 2011; Australia, 2012; Chile, 2013; Canada, 2015) indicate that animals should be checked before transport on their fitness for the journey; if not fit they should not be loaded and transported, although in some cases they may be acceptable with special provisions. Regarding competence of drivers, only in New Zealand, EU and Chile, a certificate of competence is required (Table 1). All animals should be transported for the shortest possible time (OIE, 2015). Hartung et al. (2003) propose that the welfare of the animals is limited by their needs and not by a fixed maximum transport time if vehicle and transport conditions are appropriate. Accordingly, the OIE standard for the transport of animals by land (OIE, 2015) recommends that suitable water and feed be made available as appropriate and needed for the species, age and condition of the animals, as well as the duration of the journey, climatic conditions, etc. and hence does not refer to maximum transport duration. Within the revised legislation, Table 1 shows that there are maximum continuous journey times stated for cattle, in most cases separated according to two cattle classes: young (one to six months), pregnant or lactating; and others (adult cattle). Also, maximum times without water/food are specified in most cases. Usually, the maximum journey time is equivalent to the maximum time without water and food; therefore, there are spells for unloading, resting, watering and feeding the animals, unless the vehicle is equipped with systems for watering and feeding. In these cases, space availability per animal must be increased. The OIE (2015) standard for the transport of animals by land also indicates that the space required on a vehicle or in a container depends upon whether or not the animals need to lie down or stand; when they lie down, they should be able to adopt a normal lying posture and when they are standing they should have enough space to adopt a balanced position. Again, space recommendations for transport should be stated according to the needs of the animals. One criterion for acceptable stocking densities is based on the provision of adequate ventilation and another is the minimum space required for animals based on dimensions and activities during transport (Randall, 1993). Existing legislation for the transport of cattle in most countries provides general guidelines on space requirements for cattle and refers separately to different weights and sometimes

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Minimum floor area (m2/head) standing

0.86 0.98 1.05 1.13 1.23 1.34 1.47 1.63

Mean live weight (kg)

300 350 400 450 500 550 600 650

24ª, 48 /NS

b

b

*Recommendations for safe load levels for the transportation of cattle by road from Canadian code of practice for beef cattle

0.948 1.050 1.133

Minimum space (m2/head)*

52/52

315–360 360–405 405–450

Weight range (kg)

24

Mean live weight (kg) 300 400 500 >600

b

0.86 1.06 1.27 1.50

Minimum floor area (m2/head)

12ª, 24 /24ª, 48b

b

48 b

12a





New Zealand

18a

NS



Canada

a = Young (1–6 months), lactating or pregnant cattle, b = others, NS = not specified.

Space availability

Max time without water/food

24a

Max journey duration (h)

48



NS

Drivers’ competence

Australia

Fitness for transport

Indications

325 550 >700 650

Mean liveweight (kg)

0.95–1.30 1.30–1.60 1.47 >1.60

Minimum floor area (m2/head) standing

14/14

8 (14-1-14)

NS





EU

Table 1 Maximum journey duration, space availability and other indications for cattle transport in different countries

1m2/500 kg

24/24

24

NS





Chile

NS

NS

28

NS

NS



USA

Ensuring the welfare of culled dairy cows 105

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Ensuring the welfare of culled dairy cows

classes of cattle (Table 1). This gives minimum space availabilities that range from 0.86 m2/ head for 300 kg cattle to 1.6 m2/head for 650 kg cattle, which is based on Randall (1993) equation A = 0.01 W0.78 (A = area, W = weight of animal) for standing cattle. For long distance transport, the FAWC (2013) recommends somewhat higher space allowances by using the equation A = 0.021 W0.67. In the case of Chilean legislation, only one figure for minimum space availability is given (1.0 m2/500 kg cattle), and hence, there is no difference due to cattle category; as it is common in many countries, there is a tendency towards using these minimum space availabilities commercially (Gallo et al., 2005; Gallo and Tadich, 2008). In conclusion, there are recommendations in various countries in terms of minimum space allowances for different categories of cattle and also maximum transport times without food and water, but most given values are indistinctive of animal factors like breed, age, sex, body condition score, physiological state (pregnant/non-pregnant, lactating, weaned/not weaned, etc.), physical conditions (horned/not horned) or according to ambiental factors like expected length of journey, expected climatic conditions/temperature, ventilation during the journey and whether food and water need to be supplied during transport. All these factors should be taken into consideration when transporting cattle, and these become more important in animals that, although considered fit for transport, are often in poor physical condition, pregnant, lactating or even suffering from a painful illness (lameness, mastitis). As this is often the case with culled cows, special provisions should be made for their transport in order to reduce risks of poor animal welfare.

3 Pre-transport conditions that influence the welfare of cows during transport Compared to the dairy industry, the physical condition of culled beef cows is better than that of dairy cows sent for slaughter (Grandin, 2001). When dairy cows are culled due to reproductive problems or even because they are difficult to handle, they may be in good physical shape and this may not represent a major welfare problem. However, often dairy cows are culled due to lameness, mastitis, milk fever or metabolic disorders that cause a poor physical condition, and hence, they may be too weak for transport. According to Grandin (1998, 2001), this happens when cows are pushed beyond their biological limits, and therefore, emphasis must be on preventing cows from becoming non-ambulatory. All of these conditions will frequently apply to culled dairy cows. Moreover, Riehn et al. (2014) evaluated the proportion of pregnant cows in 53 German slaughterhouses and found that 9.6% of the female slaughter cattle were pregnant on average, and more than 90% of the affected animals were slaughtered during the last two trimesters of pregnancy. According to observations by the authors in several slaughterhouses in Latin American countries, it is not uncommon to find cows giving birth at slaughterhouses during lairage. The latter is probably related to the fact that many farmers delay culling cows until late lactation, when their yields become unprofitable, thus many are in a late stage of pregnancy. Hence, the delay in culling until the economically optimal time can also carry a welfare cost. Efforts should be made to carefully inspect culled cows before loading and to coordinate each component of the pre-slaughter logistic chain to ensure the welfare of these animals (Miranda-de la Lama et al., 2014). Most regulations specify that animals should be fit for transport and that this must be checked before loading; hence there should be a better © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the welfare of culled dairy cows 107

Figure 1 Culled cow with mastitis (left) and lame (right, photo by Dr N. Tadich) on a farm before being loaded onto the transport vehicle.

enforcement of the regulations. The welfare of animals can be improved by transporting and marketing culled breeding stock when they are still fit, before they become too weak, emaciated or even downer. From an animal welfare perspective, it is extremely important to handle weak cows, and those with mastitis and lameness, carefully, because these animals will be in pain and distress, and this condition will follow or even aggravate during marketing, transport and slaughter (Fig. 1). These animals should not go through auction markets, and special conditions should be offered to them during transport (more space availability, bedding, etc.) in order to avoid further detrimental conditions during this period. If the cow is unfit for transport, a veterinarian should determine and supervise the implementation of the most appropriate killing method to ensure that animals are killed on farm without avoidable pain and distress (OIE, 2015). The recommended killing methods are free bullet, penetrating or non-penetrating captive bolt followed by bleeding, or injection with barbiturates and other drugs.

4  Welfare of culled cows during transport Welfare during transport and slaughter can be assessed by behavioural and physiological measures, but also evaluation of injuries, bruises, mortality, morbidity and carcass quality can be used as indicators of welfare during handling and transport (Warriss, 1990; Knowles, 1999; Broom, 2000; Knowles and Warriss, 2007). Most of the studies on cattle transport have been done with steers and bulls destined for meat production and there are not many studies that have investigated the effects of transport conditions, duration of journey and others in culled cows. Already in 1978 Hails pointed out that the concern shown for an animal being transported increases in proportion to its economic value and culled cows have a low carcass value: lower dressing percentage, scarce or too much fat cover and poorer grades (Van Arendonk et al., 1984; Gallo et al., 1995, 1999; U.S., 2007). This fact, and the lower proportion of culled cows compared to other cattle categories supplying meat, probably explains why most experimental studies on the effects of transport have been done with cattle categories different from culled cows. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Ensuring the welfare of culled dairy cows

Transport reviews have focused mainly on the effects of transport on the animals such as mortality, behaviour, physiological responses and meat quality, and on environmental/ external factors of the journeys, such as distance or time travelled, vehicle structure, handling, driver experience and others (Hails, 1978; Tarrant, 1990; Grandin, 1994; Knowles, 1999; Gallo and Tadich, 2005; Knowles and Warriss, 2007; Broom, 2008; Nielsen et al., 2011). Eicher (2001) refers more specifically to the transportation of cattle in the dairy industry and states that there is a need for additional research on the specific needs of different ages and stages of production of dairy cattle during transport, because transportation has become a routine management practice within dairy herds. Studies should include recovery of animals after transport and also consider the possible effects on productivity. Grandin (2001) states that the most important issue in the case of transport is starting with an animal that is fit for the journey with serious problems occurring in culled breeding stock. There are only a few commercial studies dealing with the transport of culled dairy or beef cows and culled cattle in general (González et al., 2012a,b,c). According to González et al. (2012c), calves and culled cattle appear to be more affected by transport based on the likelihood of becoming lame, non-ambulatory or dead within a journey; in the same study also significantly more culled cattle were already lame at loading than other categories, particularly females. Therefore, culled cattle are at greatest risk of experiencing stress and poor welfare during long haul transport. When culled cows are healthy and fit for the journey, most of the principles that apply for other cattle categories during transport will also apply to culled cows. However, this could be often not the case with culled cows transported in poor condition and/or because they are lame, with mastitis or other health problems, as basal values for stress indicators could be misleading.

4.1  Indicators of stress during transport Even under good conditions of transport, cattle will show physiological changes that are indicative of stress (Broom, 2000). Increases in the concentrations of various blood components (cortisol, CK, packed cell  volume, lactate, free fatty acids, betahydroxybutirate, total protein/albumin and others) and in physiological measures like heart rate, respiration rate and body temperature have been used as indicators of stress of animals during transport (Knowles and Warriss, 2007; Broom, 2008). Haptoglobin, a major acute phase protein, has also been used as an indicator of poor welfare during transport (Arthington et al., 2003). Research by Yagi et al. (2004) and Lomborg et al. (2008) in healthy dairy cows transported for 4 to 6 h evaluated the effect of short transport stress on somatic cell counts, migration of blood neutrophils and acute phase proteins in cattle and found that all these indicators increased after transport. Regarding behaviour during transport, adult cattle normally prefer to stand and will not lie down in trucks while they are moving (Knowles, 1999); however at high stocking densities or with long journeys, they occasionally lie down (Tarrant, 1990). The most common standing orientations for cattle during long distance transport are perpendicular and parallel to the direction of travel, avoiding the diagonal orientations (Tarrant et al., 1992; Gallo et al., 2000, 2001). Maintenance of balance on moving vehicles requires energy and good footing, and more animals are likely to fall down after 12 h of transportation (Gallo et al., 2000). The proportion of lying adult cattle increases with time after 12 h of transport, whereas young cattle (6–12 months) lie down earlier (Grandin and Gallo, 2007). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the welfare of culled dairy cows 109

When this happens at high stocking densities, cattle are trapped down and are unable to rise again (Tarrant et al., 1992).Transporting emaciated, lame or sick cows will render them more susceptible to loss of balance; moreover, when they fall during transport, it becomes particularly difficult for them to stand up again, and the risk of being trampled by other animals and suffocating becomes greater. When an animal dies during transport, it is because its physiological mechanisms have failed to maintain homeostasis (Knowles and Warriss, 2007), and therefore, mortality is used to quantify stress. Adult cattle are more resilient than other livestock and mortality during transport appears to be low, but young calves are more vulnerable (Knowles, 1995, 1999). In dairy cows transported to slaughter between 1997 and 2004 in the Czech Republic, Vécerek et al. (2006) found that mortality rate during transport (died in the truck or shortly after unloading) was 0.038%. Mortality increased with travel distance, and season was also a factor in the death rates of dairy cows under transportation, with higher mortality occurring in the colder periods, as opposed to warmer periods. The same authors found a growing trend in dairy cow mortality during transport throughout the time studied, which is a warning sign in relation to the welfare of these animals. Malena et al.(2007) found a mean mortality rate of 0.0396 in dairy cows transported between 1997 and 2006 in the Czech Republic, with lowest mortality in less than 50 km distance transport (0.0137%) and highest (0.1874%) in transport longer than 300 km. In the United States, mortality rate recorded at arrival at the slaughterhouse was 0.04% (U.S., 2007). The proportion of cattle arriving as downers or non-ambulatory can also be used as an indicator of poor transport. However, according to observations by the authors, in culled cows, this is commonly the result of the transport, plus the poor conditions of the animals before loading them (Fig. 2). Grandin and Gallo (2007) also indicate that some of the most severe welfare problems that occur during cattle transport are with culled cows and other animals that are sick, emaciated or debilitated, and hence of low economic value. Moreover, Grandin (1994) and Doonan et al. (2003) refer to non-ambulatory animals, which are mostly culled dairy cattle. There are several meat quality problems – shrink, carcasses bruises, high ultimate pH – that become evident only after slaughter and reflect that animals have had a poor welfare

Figure 2 Culled cows arriving non-ambulatory at a Chilean (left) and Colombian (right, photo by Dr F. Ramírez) slaughterhouse. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Ensuring the welfare of culled dairy cows

during the pre-slaughter period (Warriss, 1990; Gallo and Huertas, 2016). Shrink is related to animal welfare as it reflects that animals have suffered from prolonged hunger and/or thirst. The loss of liveweight during long journeys causes shrink and can negatively affect carcass weight (Warriss, 1990). González et al. (2012b) showed that both feeder calves and culled cattle (bulls and cows) had the greatest shrink compared to calves and fat cattle, in long distance commercial haul (>400 km, 12–16 h, without feed and water) in North America. Transport duration and cattle category were the most important factors affecting shrink. The presence of bruises on a carcass is an indicator that cattle were exposed to improper handling and transport conditions and hence reflect a welfare problem during the pre-slaughter period. Bruising is also associated with economic losses due to trimming meat cuts and poorer meat quality. Older cows and oxen suffer more from bruising than younger cattle (Strappini et al., 2010). The presence of high ultimate pH (>6.0 at 24 h post-mortem) is an indicator that cattle have been through chronic stress during the preslaughter period (Ferguson and Warner, 2008), makes meat unattractive due to its darker colour and reduces its shelf life (DFD, Hood and Tarrant, 1980). In general, the incidence of high pH meat is higher in bulls and steers than in cows (Warriss, 1990). However, Knowles (1999) indicates that the high prevalence of DFD meat found in culled cows at slaughter within the United Kingdom suggests that they find marketing and transport to slaughter particularly stressful. This is consistent with the results of Strappini et al. (2010) who found that cows transported to the slaughterhouse, passing through the market, also have a higher percentage of high pH meat than those going directly from the farm, and that the presence of bruises was also significantly associated with increased carcass pH values. So, handling culled cows gently, reducing long fasting periods without water and food, and minimizing stress will undoubtedly help improve their welfare and also allow to produce more meat of better quality for the consumers.

4.2  Causes of animal stress during transport There are many environmental/external factors related to cattle journeys that can increase stress and negatively affect animal welfare, and these are journey length, stocking density in the truck, vehicle design and maintenance, ventilation, climatic conditions, quality of roads and the standard of driving (Grandin and Gallo, 2007). The time a journey takes is generally more important than the distance travelled (Warriss, 1990) and there is often no direct relationship between them, particularly in countries with poor or geographically difficult roads, where a short distance could take many hours (Gallo and Tadich, 2008). Tarrant et al. (1992) found evidence of dehydration and fatigue after 24 h road transport and concluded that any extension of journey time or deterioration in transport conditions would be detrimental to the welfare of steers transported to slaughter. Warriss et al. (1995) concluded that a 15-h journey under good conditions of transport is not unacceptable from the viewpoint of animal welfare, based on the physiological measurements and subjective behaviour observations of castrated male cattle between 12 and 18 months of age. The findings of Gallo et al. (2000, 2001) who transported steers by road 3, 6, 12, 24 and 36 h (the latter with or without a rest stop) are similar to those of the above-mentioned authors, indicating that journeys of 24 h or more, without food and water, and at high stocking densities (500 kg/m2) negatively affect welfare and meat quality. A high stocking density or low space availability (1.05 m2 per 600 kg steer) reduces the welfare of the cattle during transport and increases the stress response, number of falls and © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the welfare of culled dairy cows 111

amount of bruising (Tarrant et al., 1992). Inappropriate space allowances can increase the frequency of falls, injuries, bruising, mortality, cortisol and creatine kinase concentrations (Tarrant et al., 1992; González et al., 2012c). González et al. (2012a) found that culled and breeding cattle in long distance hauling in North America had the fewest number of animals per trailer and hence the greatest space allowance (allometric coefficient k = 0.019–0.047, where k = space allowance/BW0.6667) compared to other cattle categories; they suggest that more space is provided to animals with poorer body condition (culled) or high value (breeding). The same authors also found that gates in the deck were used more frequently when hauling calves, breeding and culled cattle, suggesting that this is due to the fact that culled and breeding cattle are usually loaded in groups of fewer animals and there is potential mixing of animals. This has also been observed in Chile by Gallo et al. (2005) and in South America in general by Gallo and Tadich (2008); these authors mention that in order to avoid welfare problems and deaths with the consequent economic losses for the farmers, culled cows are usually transported in short hauls, with higher space allowances, in smaller vehicles, and in smaller groups of animals to local slaughterhouses. Nielsen et al. (2011) studied the effects of journey duration on animal welfare and concluded that transport of long duration is possible in terms of animal welfare provided that four issues can be dealt with, that are specific for the species and age group of the animals that are transported: the physiological and clinical state of the animal before and during transport; feeding and watering; rest and thermal environment. Hence, we consider that it would be possible to transport cattle for longer than 24 h provided that animals are healthy, have enough space to be able to rest (lie down), have comfortable bedding, have access to food and water, and other factors like ventilation, ambient temperature and humidity are controlled in accordance with the needs of the specific category of cattle transported (breed, age, sex, physiological state and others). The poor condition of culled dairy cows when leaving the farms, combined with transport stress, may become critical factors leading to impaired health and even to death during transport.

5  The effects of livestock markets on cow welfare Cows can be transported for different reasons within farms, between farms, to the slaughter house when they are culled or to livestock markets to be sold (Fisher et al., 2008). This latter implies multiple loading/unloading, extra transports, and in some cases, mixing with unfamiliar animals. According to González et al. (2012b), most of the culled cattle loads submitted to long haul transported in North America originate from auction markets (78%) and only a few from the farm/ranch (22%). Cattle loaded at auction markets are more likely to become non-ambulatory or die during transport compared to those loaded at farms or feed yards (González et al., 2012c). Something similar happens in South America, where much of the young fat cattle goes directly to the slaughterhouses, but feeder calves and culled cows often pass through livestock markets, where infrastructure and handling are poor (Gallo and Tadich, 2008). Several studies have shown that cattle passing through auction markets also suffer more bruising than those marketed directly from farm to slaughterhouse (McNally and Warriss, 1996; Weeks et al., 2002; Strappini et al., 2010) and that the most affected categories in terms of the number of bruises per carcass, as well as the size and depth of the lesions, are culled cows and oxen (Strappini et al., 2010, 2012). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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De Vries (2011) describes the general design and structure of a livestock market as composed by an (un) loading point, races, holding pens, a weighing point and the arena or stage. When cows arrive at the market, they get out of the truck at the loading point. From this point they are driven through races to the holding pens. The size and design of the races, as well as the holding pens, can differ between markets. From the holding pens cows are driven again to the arena or selling yard. A stockperson in the ring (sometimes riding a horse) moves the animal to show the audience the qualities of the selling animal. The audience has the opportunity to bid, and the animal will be sold to the highest bidder. Just before (or after) being sold, the animals are weighed at the weighing point. From the weighing point or from the arena, cows are driven to a different holding pen or directly to the loading point where they are loaded on trucks and prepare to be transported again. The size of the animal group varies in relation to the design of the holding facilities. Mixing of unfamiliar animals in the holding pen can occur. Provision of water and food depends on market regulations, but in general it is not a common practice in many countries. The movement of the cow from one stage to another inside the market might implicate stress, fear, fatigue and risk for injuries. In fact, studies on bruised carcasses from cows traded through livestock markets revealed several factors potentially harmful to the animals that impaired their welfare (Strappini et al., 2010). In this way, the gross characteristics of the bruises can be used to identify and evaluate potentially sub-optimal welfare conditions during the pre-slaughter period. The characteristics and number of bruises on Chilean cattle carcasses were studied and related to the source of the animals (Strappini et al., 2012). For a total of 258 cow carcasses (111 transported directly from farm to the slaughterhouse, and 147 cows traded via livestock market), the number of bruises, anatomical site, size, colour and shape were assessed. The number of bruises per carcass was higher in animals from markets than in off-farm animals (mean 3.8  2.0 versus mean 2.5  1.8 respectively). These results are in line with those reported by Jarvis et al. (1995) and Weeks et al. (2002) who found that 71.0% of the animals that had passed through a market showed a bruised carcass compared to 53.7% of the animals from farms. Regarding the distribution of bruises on carcasses, cows from markets showed more bruises on the hip, pin and ribs site presenting evidences of rough handling and animals beaten by sticks at markets (Strappini et al., 2012; Fig. 3).

Figure 3 Culled cows at a Chilean livestock market, showing horned cows of mixed origin at high stocking density in a pen (left) and cows being handled with sticks (right). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the welfare of culled dairy cows 113

Market animals in general showed agonistic behaviour and seemed to be excited displaying butting, mounting, defecation and vocalizations. Stockpersons of Chilean markets (De Vries, 2011) and other South American livestock markets (Gallo and Tadich, 2008) were observed using wooden sticks to poke and hit animals (Fig. 3). These findings are in line with Strappini et al. (2012) who found a high prevalence of bruises with a tram-line appearance reported on carcasses of cows coming from livestock markets in the same area of study (Fig. 4). These types of bruises are characteristic of those caused by a rounded shape object and are evidence that animals were beaten with sticks (Weeks et al., 2002). The behaviour of the stockperson towards animals is likely to depend on the behaviour of their colleagues at the livestock market and it is influenced by subjective norms. However a busy environment might also have negative influence on the human – animal relationship since the stockperson feels pressure to move the animals quickly and does not take time to guide the animal with care. Therefore, the pressure exerted by a peer group as well as the working conditions can be the cause of the use of stick and rough handling (Coleman et al., 2000). Market authorities (i.e. staff, owners, official veterinarians) must ensure that cows exposed for sale at the livestock auction are in good condition and should have the authority to decide on the humane killing of those animals unfit for onward transport. Livestock markets operators should make it very clear that unfit animals will not be accepted in their markets. Therefore, farmers must be aware of the fact that unfit cows should not be transported, and the criteria to consider when an animal is unfit for transport are given by OIE (2015). Moreover, passing culled cows through auction markets should be avoided whenever possible as it will only add to further suffering and pain, and impair their welfare.

Figure 4 Stick marks that become visible after dehiding the cow at the slaughterhouse. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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6  Welfare of cows at the slaughter plant Grandin (1994) states that although culled cows represent less than 1% of the cattle handled in U.S. slaughter plants, they suffer greatly due to rough handling.

6.1  Arrival and unloading When cattle arrive at a slaughterhouse, they are unloaded and then put in a lairage pen for ante-mortem inspection; the lairage pen also serves as a holding facility to organize cattle entering the slaughterline. Unloading should take place as soon as possible after arrival (OIE, 2015) in order to minimize further stress of the animals arriving tired from the journey. Regarding the arrival of cattle to the slaughterhouses, the longest unloading delays were found in culled cattle in North America (González et al., 2012b). In Colombia, Ramírez and Gallo (2012) observed that the mean waiting time for cattle before being unloaded was 6.3 h; there were frequently fallen animals in the trucks (Fig. 2), particularly weak cows, and the delay was due to the fact that cattle had to be unloaded only between 7.00 and 11.00 am at the slaughterhouse. These delays are common in other South American countries as well (Gallo and Tadich, 2008) and undoubtedly affect the welfare of the animals. Non-ambulatory (downer) cattle are a major problem area and dairy cattle are 75% of the downers (Grandin, 1994). As observed by the authors, cattle that arrive as nonambulatory in South American slaughterhouses are also mainly culled cows (Fig. 2). When unloading non-ambulatory cows, they should be handled and moved as little as possible in order to avoid producing more pain and distress on the animal. Dragging of downed or crippled livestock is forbidden in most countries. Slide boards and cripple carts are helpful to unload disabled cattle and further transport them to the emergency slaughterhouse to be immediately slaughtered. If this is not possible, the disabled animal should be stunned on the vehicle, before unloading, and slaughtered immediately after. However, it is still common to see improper unloading of non-ambulatory cows, being lifted or hoisted from different parts of their bodies instead of being humanely killed on the truck (Fig. 5).

Figure 5 Cows being inadequately unloaded by lifting from their legs after arriving non-ambulatory at the slaughterhouse. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the welfare of culled dairy cows 115

6.2  Lairage duration and conditions It has been well established that from an animal welfare perspective, as well as from a meat quality point of view, lairage time should be as short as possible (Tadich et al., 2005; Ferguson and Warner, 2008). The OIE standards for animal welfare (2015) recommend that waiting times at the slaughterhouse be kept to a minimum and not be longer than 12 h; if animals need to be kept longer, food should be offered to them. During lairage, cattle have access to water but not to food usually. The possibilities of resting are few. This may be due to the environment, which may not provide suitable conditions for rest, as there will be noise, unfamiliar smells and the presence of people and other animals. Gentle handling in well-designed facilities will minimize stress levels and improve efficiency at the slaughter plant; therefore, constant monitoring of handler performance and good maintenance of handling structures are required to maintain high standards of welfare (Grandin, 2007). The authors have observed in several countries in South America that, with the exception of emergency slaughter, culled cows will usually remain in lairage for a longer period than other cattle categories, because preference for slaughter is given to steers and heifers that will render better carcasses and meat quality than culled cows. In Colombia, Ramírez and Gallo (2012) and Ramírez (2016) found that cattle in general remain between 12 and 118 h in lairage (mean 39.98 h, Fig. 6 left) and that culled cows experiment the longest lairage times, mostly with access to water but no feed. A similar feature was found by Gallo et al. (1995); with a mean of 34 h lairage for cattle in general, culled cows waited 39 to 51 h. Although lairage times are being reduced in most countries due to OIE (2015) recommendations and the negative effects on meat quantity and quality (Ferguson and Warner, 2008), in Chile, cattle still remain for over 12 h in lairage, as they usually arrive the evening before they will be slaughtered. This will affect their welfare in general, but particularly in the case of cows that are culled because of mastitis and lameness, which are painful and cows have to stay in pens without the necessary comfort. In fact, Meneses et al. (2005) examined 500 dairy cows at a slaughterhouse and found that 71% of them presented hoof lesions, not considering whether they were lame or not. The frequency of presentation of hoof lesions obtained in this study at a slaughterhouse is much greater than the farm prevalence of lame cows (Flor and Tadich, 2008; Hernández-Gotelli and

Figure 6 Dead and non-ambulatory cattle in lairage pens at a Colombian slaughterhouse (left, photo by Dr M. F. Ramírez) and culled cows during lairage at right, showing that they mainly remain standing. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Tadich, 2015); the higher prevalence of lame cows at slaughterhouses compared to farms shows that animal welfare issues in the culled cows concentrate at slaughterhouses. Observations on the behaviour of cattle during lairage showed that the time taken for cattle arriving from markets to lie down after arrival at the slaughterhouse was less compared to those arriving directly from farms, and they were also lying down for a longer period (Cockram, 1991). Opitz et al. (2012) found that after short transport (100 km) during long periods of lairage (19 h) resting behaviour of culled cows (latency and duration of lying down) was uncommon, moreover a high number of interactions among them occurred (Fig. 6 right). Most cows remained standing during the whole period, only 24% of all cows were lying down at least once during the lairage period; the time they were lying down corresponded only to 5% of the lairage time. The physical condition also affected the behaviour of cows in lairage: cows in better condition interacted more and rested less. Hence, culled cows, particularly those that feel pain due to lameness or mastitis, will not rest and do not benefit from a long lairage.

6.3  Stunning and slaughter Dairy cattle, cows in particular, have a close human–animal relationship and therefore a small flight zone which makes handling sometimes difficult when driving cows from the lairage pens to the stunning point at the slaughterhouse; as they are not afraid of people, they are difficult and slow to move. Strappini et al. (2013) found that after relatively short transport times (4 h) directly from farm to slaughterhouse and long lairage times (12 h) most bruises in culled cows were the result of circumstances at the slaughterhouse; either due to human–animal, animal–animal or animal–facility interactions. One of the main

Figure 7 Carcasses of culled cows showing bruises, caused by falling of guillotine doors on their backs. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the welfare of culled dairy cows 117

problems was guillotine doors falling on the back of cattle. As cows are usually of larger size than steers and heifers, they are at greater risk of being hit with guillotine doors, when these doors are used to push cattle forward (Fig. 7). The OIE (2015) recommends that cattle be immobilized before stunning and also that methods of restraint that cause avoidable suffering not be used. Grandin (2007) states that behavioural principles should be used for restraining animals, as this will enhance animal welfare and will reduce stress and injuries. Restraining devices include head gate designs, hydraulic chutes with adjustable sides, belly lifts and rear pushers. In all cases these devices should have enough pressure to provide the feeling of restraint, but avoid uncomfortable pressure points on the animal and pain on the animals. Immobilizing devices improve the efficiency of stunning (Gallo et al., 2003), but they can also produce stress if they exert excessive pressure on the animal (Ewbank et al., 1992). Muñoz et al. (2012) found that in 6.1% of the cases cattle restraint was incorrect, and this was significantly associated with vocalizations; cows were less affected by this, probably because of being more tame and familiar with holding structures on farm. However, large dairy cows were more affected than other cattle categories by the falling of guillotine doors on their backs. The most common method for stunning cattle is the captive bolt, which in its mode of action can be penetrating (which impacts the skull and enters the bolt into the brain) or non-penetrating (which only impacts the skull) (HSA, 2006). In order to avoid a possible return to consciousness, when using non-penetrating concussion stunners, animals should be bled within 30 s and it is not recommended for cattle of less than eight months of age, for mature stock bulls, or for aged cows (HSA, 2006). The OIE (2015) recommends that non-penetrating captive bolt be used only when there is no alternative method. The physical signs of an effective stun are: animal collapses, no rhythmic breathing, fixed/ glazed expression in the eyes, no corneal reflex, relaxed jaw and tongue hanging out (HSA, 2006). Concha and Gallo (2009) compared the effectiveness of non-penetrating captive bolt between steers, heifers and cows during the stunning process, and found that cows had a higher presence of sensibility signs (rhythmic breathing, eye movements and corneal reflex, vocalizations and head lifting), the longest intervals between stunning and sticking, and also more frontal bone fractures, all indicators of incorrect stunning and impaired welfare. Stunning efficacy can be significantly improved by training stunning operators (Gallo et al., 2003). Most of the welfare problems that culled cows suffer during stunning at the slaughter plant could be avoided by proper animal handling, adequate design of handling and stunning facilities and by training operators who understand that culled cows are sentient beings, independent of their lower economic value.

7 Conclusions Culled cows should leave the farm before they become too weak or emaciated; emphasis must be on preventing cows to become non-ambulatory. If cows become non-ambulatory on farm, they should be euthanized as soon as possible on site and not transported. If cows become non-ambulatory during transport or during lairage, they should be moved as little as possible so as to avoid further pain and slaughtered without delay.

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Culled dairy cows should go directly from the farm to a slaughterhouse and not traded through cattle markets. Duration of transport for culled dairy cows should be as short as possible and conditions of transport should consider providing a larger space availability than for steers and heifers, and comfortable bedding as to lie down. Slaughterhouses should be organized in such a way to give preference to weak dairy cows, so that they can be humanely unloaded from the vehicles and slaughtered as soon as possible after arrival. The training of people handling animals during transport and at the stunning point should incorporate the principle that all farm animals are sentient beings, regardless of the lower economic value of culled cows compared to other cattle categories. There is need for more studies on the welfare of the different cattle categories during transport, particularly culled cows, and on the handling of them at the slaughterhouses, as there is some evidence that animal welfare during these procedures is greatly impaired in culled dairy cows.

8  Where to look for further information For those who would like further reading on the welfare of culled dairy cows during transport and slaughter, and considering that information on this specific subject is scarce, we suggest to review the general legislation on transport and slaughter of animals for the countries of interest. We also recommend to read the OIE guidelines on animal welfare (OIE, 2015), particularly the standards on welfare of animals during transport and slaughter. For Spanish speaking readers we would also suggest the third edition of the book Bienestar Animal: una visión global en Iberoamérica (Mota-Rojas et al., 2016) which contains several chapters on good handling practices for cattle during the pre-slaughter period, including transport.

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Weeks, C. A., McNally, P. W. and Warriss, P. D. 2002. Influence of the design of facilities at auction markets and animal handling procedures on bruising in cattle. Veterinary Record 150: 743–8. Yagi, Y., Shiono, H., Chikayama, Y., Ohnuma, A., Nakamura, I. and Yayou, K. 2004. Transport stress increases somatic cell counts in milk and enhances the migration capacity of peripheral blood neutrophils of dairy cows. Journal of Veterinary Medical Science 66 (4): 381–7.

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Chapter 6 Ensuring the health and welfare of dairy calves and heifers Emily Miller-Cushon, University of Florida, USA; Ken Leslie, University of Guelph, Canada; and Trevor DeVries, University of Guelph, Canada 1 Introduction 2 Newborn calf vitality 3 Colostrum management 4 Health management 5 Housing considerations 6 Feeding management 7 Managing weaned calves 8 Summary 9 Where to look for further information 10 References

1 Introduction Over the last two decades, there have been many advances in the nutrition, housing and health management of young, dairy replacement heifers. Nevertheless, national survey results suggest that approximately 1 out of every 10 dairy heifers in the United States die before weaning. Individual studies from Europe, Scandinavia, Australia and other parts of the world have reported less alarming results. Yet, vast improvements in the success of rearing of young dairy calves are possible and are urgently needed. This chapter will delve into aspects of the management of birth, improvement of calf vitality, success of colostrum feeding, prevention of neonatal disease, alleviation of pain at common procedures, provision of optimal housing, execution of accelerated feeding programmes, stress-free weaning efforts and maintenance of efficient rearing by optimal nutrition and housing of post-weaned dairy heifers. In each of these areas of emphasis, numerous recent advances will be presented. However, hurdles and bottlenecks to achieving meaningful improvements in the success of heifer-rearing programmes, particularly as they relate to calf welfare, will also be described and discussed.

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2  Newborn calf vitality 2.1  Management of calving to improve calf vitality The process of parturition can be a stressful, traumatic and hazardous event in the life of both the cow and calf. Dystocia is defined as a difficult or abnormal calving event, due to a prolonged unassisted parturition process, or due to a prolonged or severe assisted calf delivery (Mee, 2004). Unfortunately, the definition of dystocia can be subject to varying interpretations. A number of scoring systems to assess the degree of dystocia have been developed, with different terminologies and numbers of categories. Generally, higher scores reflect a greater level of assistance, as well as a larger number of people assisting and a greater amount of mechanical force required to deliver the calf (Meijering, 1984). As the prevalence of dystocia has increased over time, more attention has been focused on maintaining the health and longevity of cows rather than lack of vitality in the newborn calf, even with mounting evidence that dystocia results in both short- and long-term implications for calf health, performance and welfare. A recent review has documented and discussed the risk factors, characteristics, assessment, resulting outcomes and strategies for improvement of neonatal calf vitality (Murray and Leslie, 2013). General factors associated with dystocia may include pelvic dimensions of the dam, calf size and calf presentation. Maternal factors include weak labour, insufficient dilation of the cervix and uterine torsion (Meijering, 1984). In the end, the most common cause of dystocia is foeto-pelvic disproportion, which is a mismatch in dam pelvic size and calf weight (Mee, 2008a), most commonly occurring in primiparous cows delivering bull calves. Yet, it has been shown that calf birth weight was a better predictor of calving difficulty than calf gender alone (Johanson and Berger, 2003); in fact, for every 1 kg increase in birth weight, there was a 13% increased probability of dystocia. As an example, if a population of Holstein calves that on average weigh 45 kg at birth have a probability of dystocia at 10%, the probability of dystocia in a calf that weighs 46 kg would be 11.3%. The Holstein breed has the highest ratio of calf birth weight to dam body weight, averaging 7.1%, clearly resulting in the highest incidence of dystocia (Johanson and Berger, 2003). It is noteworthy that the practice of recording calf birth weights and weaning weights has not been widely adopted in the dairy industry. It is emphasized, and encouraged, that the accurate recording of birth weights could be an important component of making advancements in breeding and management programmes to reduce the incidence of dystocia, and subsequently to improve the sustainability of managing parturition in the dairy industry. Calvings that are termed to be dystocia usually require human intervention. Yet, inappropriate timing of intervention, or excessive force applied during delivery, may result in foetal trauma, stress and often in stillbirth (Schuijt, 1990). Dystocia can also lead to a cascade of behavioural and physiological responses which may have implications for calf vitality, as well as for the long-term health, well-being and productivity of calves that survive. Prolonged or assisted delivery can cause a variety of effects in the calf, including injury, inflammation, hypoxia, acidosis, pain and an inability to maintain homeostasis (Lombard et al., 2007). Each of these effects can further contribute to a reduced state of well-being in the newborn calf. Neonatal vitality is essential to the health, survival and welfare of the calf. If the calf is not vital at birth, it may be unwilling, or unable, to get up and suckle colostrum in a timely manner. Early colostrum intake improves passive transfer of immunoglobulins (Ig), energy uptake and thermoregulation. The impacts of colostrum © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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management on long-term health status and overall performance will be reviewed later in this chapter (Godden, 2008).

2.2  Characteristics of impaired calf vitality Calf vitality is defined as having the capacity to live and grow, with physical and mental energy and strength. Impaired calf vitality usually results from inflammation, pain, injury, inability to maintain homeostasis, hypoxia and acidosis (Murray and Leslie, 2013). These physiological responses can have behavioural repercussions. For example, there is often a reduced motivation to perform natural behaviours for survival, including standing up and suckling colostrum after birth (Barrier et al., 2012). When excessive force is applied during the delivery process, trauma inflicted can cause severe injury and pain (Schuijt, 1990). Injuries to the vertebral column are common following dystocia and include vertebral fractures, myelomalacia, spinal cord compression or a severed spinal cord. In newborn calves with thoracolumbar fractures, haemorrhage in and around the kidneys, adrenal glands and musculature are consistent necropsy findings. Fractures of the vertebrae, as well as ribs, may increase the risk of abdominal trauma, which may subsequently lead to liver rupture and abdominal haemorrhage. Neonatal vertebral fractures, as well as femoral and mandibular fractures, occur infrequently. If such injuries are not immediately fatal, calves are usually weak and lack mobility. Calf weakness may interfere with the natural interactions and behaviours that promote health and survival. Systemic acidosis, due to premature rupture of the umbilical vessels, is another major consequence of prolonged dystocia or forced extraction. Umbilical cord rupture terminates the oxygen supply to the foetus from the placenta. When this rupture occurs prematurely, before the calf is able to regulate its own respiration, oxygen supply diminishes, leading to the rapid development of asphyxia and respiratory acidosis. Intense and prolonged labour contractions and trauma during forced extraction can exacerbate this effect, subsequently inducing a state of acid–base imbalance and prolonged hypoxia. If the hypoxia is severe, foetal tissues will derive energy from anaerobic glycolysis, resulting in the production of lactic acid, inducing a state of metabolic acidosis and compromised survival (Grove-White, 2000). Subsequent implications in calves include inability to thermoregulate, aspiration pneumonia, oedema, bleeding and death (Poulsen and McGuirk, 2009). Newborn calves are particularly susceptible to environmental conditions at birth, and are challenged to maintain thermoregulation by shivering thermogenesis in muscle tissue, as well as by mobilizing energy reserves through non-shivering thermogenesis in brown adipose tissue. It has been demonstrated that following dystocia, the reduced ability to control body temperature found in stressed calves may be due to hypoxia, acidosis, low plasma thyroid hormone levels and, subsequently, decreased mobilization of body lipids (Vermorel et al., 1983). Another method of generating body heat in newborn calves is through physical activity. Simple natural behaviours such as standing up, walking and consuming colostrum may be challenging for calves with low vitality, especially in temperatures outside of their thermoneutral zone. Energy and heat acquired through colostrum ingestion may also be delayed or reduced in calves with low vitality (Grove-White, 2000; Barrier et al., 2012). The effects of calving difficulty on newborn calf vitality and its association with blood pH, the apparent efficiency of immunoglobulin G (IgG) absorption (AEA) and weight gain have been recently studied (Murray et al., 2015a). A total of 45 calving events (n = 48 calves) were monitored from the first sight of foetal membranes. All calves were assessed at the time of first attaining sternal recumbency (SR), 2 and 24 h, 7 and 14 d of age. Measurements © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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included time to SR, rectal temperature, respiration and heart rate, analysis of bloodgases and other blood measures, suckling response, time to standing, passive transfer of IgG and weight gain. At 2 h after birth, calves were separated from their dam and fed a commercial colostrum replacer containing 180 g IgG by oesophageal tube feeder. Calves born following dystocia had lower venous blood pH and took longer to attain SR, and attempt to stand, than those born unassisted. Duration of calving interacted with the number of people required to manually pull the calf, as a significant predictor of pH at SR. No association was found between pH at SR and AEA. However, reduced AEA was found in calves that were female, and in calves that did not achieve SR within 15 min of birth. A longer calving duration, being born in July or August compared to June, and a shorter time spent standing in the first 2 d of life, were all significantly associated with reduced weight gain to 14 d. From this study and other research, it is clear that factors at calving impact newborn calf physiology, vitality and subsequent weight gain (Murray and Leslie, 2013; Murray et al., 2015a).

2.3  Assessment of newborn calf vitality In developed countries, human pre- and post-natal care programmes have resulted in a very high rate of success for prevention of problems in newborn babies. Part of this success is due to a standard requirement for the completion of a health and vigour score within minutes of birth. This method of assessment of newborn vitality, commonly termed the ‘APGAR score’, was created by Virginia Apgar, M.D., over half a century ago (Apgar et al., 1958). It has become the standard procedure used for human newborns since that time. The APGAR score measures Appearance, Pulse, Grimace, Activity and Respiration. A rating of 2, 1 or 0 is given to each sign. The score is assessed at 60 s after delivery, and is repeated, based on a decision model, to determine a course of action until the baby is deemed healthy and vigorous. The APGAR score lacks sensitivity, and was not designed for the purpose of making long-term predictions about future health and growth. However, the APGAR score is highly specific and works well to guide physicians in providing care to individuals that may be at considerable risk immediately after birth (Murray and Leslie, 2013). Decades of efforts to develop and implement a modified APGAR score for use with calves have been summarized (Murray and Leslie, 2013). Yet, there has been a general lack of research to identify risk factors at birth that can be used to predict perinatal morbidity and mortality in calves. Knowledge concerning these factors was considered to be critical for the development of a practical calf vigour assessment tool, as well as a decision model to assist farmers in determining best practices to aid calves with low vitality to improve health and survival. Recently, a method to assess newborn calf vitality has been created and implemented (Murray et al., 2015b). As well, additional studies have shown that low vitality can be detrimental to survival, development and welfare (Murray et al., 2015c). From this work, researchers at the University of Guelph have developed and validated a dairy calf VIGOR score that is associated with the physiological status of the calf and the degree of calving difficulty. The dairy calf VIGOR score assesses Visual appearance, Initiation of movement, General responsiveness, Oxygenation, as well as heart and respiration Rate of the calf (Murray et al., 2015b) (Fig. 1). Calves with lower cumulative scores using the VIGOR assessment system are considered to have poor vigour, are at greater risk for problems and may need immediate attention and critical care. Yet, further information on approaches to mitigate and manage the effects of reduced vitality is greatly needed. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Figure 1 University of Guelph: Calf Vitality Score Sheet (With permission from: Murray et al. 2015b).

2.4  Methods to improve newborn calf vitality Various interventions may be required to assist calves with compromised vigour to aid in long-term health and survival. Such interventions include respiratory resuscitation, thermal support, manual feeding of colostrum and the administration of non-steroidal © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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anti-inflammatory drugs (NSAIDs). First, immediate supportive care to high-risk calves, following dystocia and assisted calving, includes establishing an open airway, stimulation of breathing and provision of circulatory support. Veterinarians must work with producers to establish protocols and provide the necessary training and equipment to allow herd staff to deliver immediate and aggressive intervention when needed. Some larger herds have implemented a resuscitation kit, including a stethoscope, rectal thermometer, compressed air device, needles, suction pump and oxygen delivery equipment (Mee, 2008). In addition, herd staff can be trained to perform simple physical techniques, such as using fingers to clear the mouth and nose of fluid, and stimulating breathing as soon as the calf’s thorax has emerged from the cow, even in a hip-locked calf. Breathing is enhanced by sitting the calf in sternal recumbency, in a ‘dog sitting’ posture, so that both lungs are more easily ventilated. In this position, the calf should be briskly dried with a clean, dry towel, rubbing from tail head to the head along the topline, and then rubbing and stimulating the head, ears, eyes and nose. Pinching across the nasal septum can stimulate the inspiratory reflex. Finally, pouring ice cold water on the head, or into the ear, can induce a gasp reflex. Suspending the calf, such as by hanging it over a gate, is vehemently discouraged (Mee, 2008). After establishing an open airway, breathing and circulation, ongoing supportive care should include continuation of intranasal oxygen for very weak calves, drying the calf completely, supporting it in sternal recumbency and providing supplemental heat to prevent hypothermia. Delivery of oxygen by herd staff, with a face mask or intranasal tube, offers a valuable opportunity for improvement in calf vitality that is clearly underutilized. Furthermore, many calves experiencing prolonged dystocia will be acidotic. For these more severe cases, the administration of 50–100 mL of 8.4% sodium bicarbonate solution should be considered (Mee, 2008). While these approaches to the therapy and management of impaired neonatal calf vitality are soundly based, and make therapeutic sense, there is a profound lack of controlled clinical research to validate their usefulness under commercial farm conditions. In general, there is a clear need for more research in this area. Although it is assumed that an assisted calving is a painful process for both the dam and the calf, pain management in newborn calves after an assisted calving is largely not addressed (Murray et al., 2015b). Yet, it is logical that reduced calf vigour can result from pain and inflammation caused by soft tissue injury during calving. New research suggests that alleviation of this pain may have benefits in improving behaviour, total milk intake, success of passive transfer and, subsequently, reduce the risk of developing disease (Murray et al., 2015b). In a recent study, shortly after birth, calves were randomly assigned to receive either a 1 mL subcutaneous injection of an NSAID, meloxicam, (20 mg/mL; Metacam®. Boehringer Ingleheim Vetmedica Inc., St. Joseph, MO) or 1 mL of a placebo solution for control calves (Murray et al., 2015c). Meloxicam-treated calves had greater improvements in vigour and suckling reflex than placebo-treated control calves. In a second placebo-controlled field study, the administration of a 1 mL (20 mg/mL) subcutaneous injection of meloxicam resulted in improved overall health, and improved weight gain in the first week of life in calves born following an assisted calving (Murray et al., 2015b). Clearly, this early research suggests that meloxicam therapy shows promise for improving health and growth, particularly for calves born with assistance. However, more research is needed to describe the value of providing pain management to dams and calves following an assisted calving. To be specific, it would be very useful to determine © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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if the administration of NSAIDs to calves following dystocia can reduce the time to standing, increase colostrum absorption, as well as improve overall calf survival, health and welfare.

3  Colostrum management Colostrum management is the single most important management factor in determining dairy calf health and survival (Godden, 2008). Nevertheless, a significant proportion of dairy calves suffer from failure of passive transfer, contributing to excessively high preweaning mortality. A successful colostrum management programme requires attention to 5 key elements (The 5 Qs), including Quality, Quantity, Quickness, SQueeky Clean (Cleanliness) and Quantifying (monitoring) the programme results. As stated above, achieving early and adequate intake of high-quality colostrum is a critical factor in determining health and survival of the neonatal calf. Successful passive transfer is defined as having a serum IgG concentration 10 g/L when the calf is sampled between 24 and 72 hrs of age. In addition to reduced risk for pre-weaning morbidity and mortality, long-term benefits associated with successful passive transfer include reduced mortality in the post-weaning period, improved rate of gain and feed efficiency, reduced age at first calving, improved first and second lactation milk production and reduced tendency for culling during the first lactation (Godden, 2008). Delivery of sufficient colostrum to provide 150–200 g of IgG to the calf, within a short time after birth, should result in an acceptable level of failure of passive transfer (FPT), such as less than 10% of calves. However, FPT rates of approximately 20% are commonly reported (Trotz-Williams et al., 2008), indicating that a significant opportunity still exists for many herds to improve colostrum management, and in turn enhance calf welfare and both short-term and long-term performance. The quality of colostrum chosen to be fed to newborn calves is the first critical step. Colostrum has numerous important constituents that are in their greatest concentrations at first milking, and decline steadily in the transition milk over the next 2–3 days. Highquality colostrum is considered to have an IgG concentration >50 g/L (Godden, 2008). Breed and age of the cow are inherent factors affecting colostrum quality, but several other important factors can be managed by producers. Provision of a balanced ration to dry cows, which promotes high dry matter intake, and is accompanied by unrestricted access to water, is very important. Stressors during the dry period must be minimized, including heat stress and overcrowding. Excessively short dry periods, such as fewer than 21 days, must be avoided. Late lactation and/or early dry period vaccinations will enhance specific community against selected pathogens. Finally, harvest of the colostrum within 1–2 hrs of calving will ensure optimal IgG content (McGuirk and Collins, 2004). It is clear that most dairy producers have limited information about the quality of the colostrum that is being fed. Yet, cow-side testing of colostrum quality can be easily performed. There are two simple, rapid, indirect tests to predict colostrum IgG concentration. The colostrometer is a hydrometer instrument that estimates IgG concentration by measuring colostrum density. However, factors such as content of fat and other solids, and temperature, will affect the accuracy of the colostrometer reading. Alternatively, a Brix refractometer measures sucrose concentration (Brix %), which is positively correlated with IgG in colostrum. Using a Brix cut-point of 22% has good © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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accuracy (sensitivity 90.5%; specificity 85%) to identify high-quality colostrum (IgG >50 g/L; Bielmann et al., 2010). Poorer quality colostrum may be saved for the second or third feeding. If less than 90% of cows are producing high-quality colostrum, the prepartum and just-fresh cows should be evaluated to improve the overall quality of colostrum harvested. The goal is to deliver 150–200 g IgG to each newborn calf. As such, the volume of colostrum to be fed will depend on the quality. For example, if the colostrum had 50 g/L IgG and we fed 4L, then we would deliver 200 g IgG. Yet, since most producers do not measure colostrum quality, it remains to be a guess as to the necessary quantity to be fed. The likelihood of delivering at least 150–200 g IgG to the calf is improved by feeding a larger volume (3 to 4L) at the first feeding, and at least within the first 6 hrs after birth. Age of the calf at first feeding is a critical factor affecting the efficiency of Ig absorption. The efficiency of IgG transfer across the gut epithelium is optimal in the first 2–4 hrs after birth. Yet, absorption progressively declines over time, with closure being complete by approximately 24 hrs (Godden, 2008). As such, producers should aim to hand feed colostrum to all calves within 1–2 hrs after birth, and certainly by not more than 6 hrs of age. Fresh colostrum can be a source of infectious pathogen exposure to newborn calves (Godden, 2008). Besides exposure, high coliform counts in colostrum are associated with reduced IgG absorption, and an increased risk of illness (Godden and James, 2014). Producers need to minimize the level of bacterial contamination and risk for pathogen exposure through colostrum. Simple strategies to achieve this goal include not letting the calf suckle the dam, and appropriately preparing the cow’s teats prior to colostrum harvest. Colostrum should not be pooled from multiple cows if it is to be fed fresh. All colostrum milking, storage and feeding equipment should be properly cleaned, sanitized and dried between uses. Fresh colostrum should be fed within 2 hrs of harvest, or frozen for storage. Additional tools that may be helpful to reduce pathogen exposure through colostrum include feeding commercial colostrum replacers or heat-treating colostrum. Good quality colostrum replacement products can offer a consistent and convenient source of Ig for newborn calves, when high-quality, clean colostrum is not available. Also, studies have demonstrated that heating colostrum to 60°C (140°F) for 60 min results in a significant reduction in colostral bacterial counts, with no significant reduction in IgG concentration. Heat treatment reduces the risk of pathogen exposure, while enhancing the efficiency of absorption of IgG by the calf, thereby resulting in improved health in the period from birth to weaning (Godden et al., 2012). The final step in effective colostrum management is to monitor the programme. This step can be done by utilizing a simple, inexpensive and rapid indirect test, such as serum total protein (STP, g/dl) or serum Brix (%) measurements, to estimate the proportion of calves with FPT. Test results should be interpreted at the group-level, not for each individual animal. At least 12 or more clinically healthy 1–7-day old calves should be tested. For the colostrum management programme to be deemed successful, 90% of calves tested should have an STP measure 5.2 g/dl (Godden, 2008) or a serum Brix measure 8.4% (Deelen et al., 2014). If a higher proportion of calves fail than expected, then the previously described 4 Qs should be investigated and opportunities to make improvements should be identified. Routine monitoring should help producers to quickly identify and correct problems. In summary, the colostrum management programme should include the feeding of high-quality, clean colostrum in sufficient quantity, soon after birth, and achieve a proportion of calves with successful passive transfer of IgG of 90% or greater. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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4  Health management 4.1  Management of pain Pain is an unpleasant and emotional experience, involving both a physiological and a psychological component that can reduce an animal’s ability to experience normal pleasures or impede natural functioning (Anderson and Muir, 2005). Pain arises via chemical, thermal or mechanical stimuli that are actually, or potentially, damaging to the tissues. Research has shown that many of the common procedures associated with livestock husbandry, such as dehorning or castration, are painful to the animal. Some methods are less painful than others, and some may continue to cause pain for hours after the procedure. Signs of pain in animals are varied and are not necessarily obvious. Researchers have worked on finding effective ways to alleviate this pain, as freedom from pain is a basic tenet of animal welfare. Pain control should incorporate a combination of anaesthetics, sedatives and/or analgesics that are known to be effective at controlling pain, both during and after the painful procedure in question. Disbudding and dehorning (DD) calves are common management procedures performed on almost all dairy farms. A general review concerning DD has been published by a task force of the American Veterinary Medical Association (AVMA Animal Welfare Division, 2014). Appropriate DD practices are important for the welfare of the calf, as well as for public perception of the dairy industry. In particular, minimizing pain associated with DD is important to limiting the pain-stress-distress cascade that creates altered behavioural and physiologic states. Pre-emptive analgesia can be accomplished with sedation, general anaesthesia, local anaesthesia, as well as with pre- and postoperative administration of NSAIDs. A summary of currently available research on pain assessment and management following DD has also been published (Stock et al., 2013). Evidence of pain associated with DD include behavioural responses (head shakes, ear flicking; Faulkner and Weary, 2000) and increases in cortisol responses (Petrie et al., 1996) in calves dehorned without pain management. Behavioural responses to pain are reduced using both short-lived local anaesthetic (Stafford and Mellor, 2005) and longer-lasting analgesics (Faulkner and Weary, 2000). While behavioural and physiological changes associated with painful procedures can provide indications of arousal reflecting changes in affective state, novel research in this area has advanced our understanding of affective state. Neave et al. (2013) reported that dairy calves, trained to associate a visual stimulus with a milk reward, were less likely to judge ambiguous stimuli as rewarding after they had been disbudded than they had been before the procedure. These results indicate a negative cognitive bias in calves experiencing pain. Two interesting surveys of bovine veterinarians and dairy producers in Ontario, Canada, have been conducted a decade apart. These investigations provide the opportunity to determine if DD protocols have changed over the past decade and to look at factors associated with the adoption of pain control practices. The first study was conducted in 2004 (Misch et al., 2007). More recently, 93 bovine practitioners from 51 different clinics and 165 licensed producers of the Dairy Farmers of Ontario completed the survey in 2014 (Winder et al., 2015). In the latter study, over 90% of veterinary clinics reported that veterinarians or their technicians performed DD for about 30% of their dairy clients. Furthermore, over 95% of veterinarians reported training producers concerning appropriate DD methods, including the use of local anaesthetic. While the percentage of veterinarians using local © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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anaesthetic, sedatives and NSAID products varied with the age of animal involved, there was considerable use of these approaches in the DD protocols being implemented. Interestingly, over 70% of veterinarians who had been practising for over 10 years reported changing their DD practices since 2004 (Winder et al., 2015). Common changes were the increased use of NSAIDs, sedation and local anaesthetic. Approximately 73% of the dairy producer respondents reported performing DD themselves, with the remaining 27% reporting that they have a veterinarian perform this procedure. A substantial percentage of producers performing DD themselves were using a local anaesthetic, sedation and NSAID therapy. Over 60% of producers reported changing DD practices in the past 10 years. Common changes included the addition of local anaesthetic and performing DD at a younger age. In fact, the use of local anaesthetic reported in the recent survey was far higher than reported a decade earlier (62% vs. 22%). It is noteworthy that the most common influence cited by producers for their changes was the herd veterinarian. Use of NSAID therapy by veterinarians was also far higher than previously reported. A strong relationship between producer and veterinarian was associated with the adoption of pain control. Veterinarians can clearly play a key role in improving DD practices for dairy calves, as well as perhaps a number of other practices directly related to the sustainability of dairy production. Identifying factors associated with best practices may help veterinarians target appropriate educational opportunities for their dairy clients. In the end, it is important to emphasize that the inclusion of polledness in selection indexes and long-term breeding strategies has the potential to reduce and eventually eliminate the need to dehorn. However, while some polled Holstein sires are commercially available, there is minimal evidence of a major impact with limited use of these animals.

4.2  Morbidity and mortality from common diseases Calfhood disease continues to be an important, and global, problem on dairy operations. Neonatal calf diarrhoea (NCD) and bovine respiratory disease (BRD) are the most common causes of morbidity and mortality in young dairy cattle. There is a wide variation in the incidence of these calfhood diseases, with substantial impacts on many commercial dairy operations. Previous studies reported overall calfhood morbidity of 35% (Waltner-Toews et al., 1986a). Specific incidence risks of NCD and BRD of 29% and 39%, respectively, have been documented (VanDonkersgoed et al., 1993; Donovan et al., 1998a). Mortality risk during the first year of life ranged from 2.1 to 14.0% depending on the year, population and age of calves (Waltner-Toews et al., 1986a; Gulliksen et al., 2009). It is important to emphasize that the large differences in the reported morbidity and mortality risk may be heavily influenced by many calf-level and herd-level risk factors, as well as by the case definitions used, age of the calves, study design and geographical influences. Understanding the factors associated with morbidity, mortality and growth is an essential step towards improving calf health and performance. Several pivotal studies have proposed that the key risk factors include farm size, concurrent disease, colostrum management, calving factors, perinatal treatments, housing, feeding, genetics and environmental factors (Waltner-Toews et al., 1986b,c; Lundborg et al., 2005; Gulliksen et al., 2009). Interestingly, systemic viral vaccination of commercial, pre-weaned dairy heifer calves did not have a significant impact of the incidence of BRD, mortality or growth (Windeyer et al., 2012). Recently, a landmark project in Canada has intensively explored and elucidated risk factors for neonatal disease (Windeyer et al., 2013). Risk factors for NCD included weight © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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at enrollment, occurrence of other diseases before 2 weeks of age and an interaction between season of birth and herd-level incidence risk of NCD. Risk factors for BRD included herd-level incidence risk of BRD, season of birth, navel dipping, the occurrence of other diseases before 2 weeks of age, FPT and method of temperature control in pre-weaning housing. Risk of mortality was increased in calves treated for BRD or other diseases. This study reinforced the importance of disease prevention by illustrating the interconnectedness of various diseases, mortality and growth. In particular, the importance of passive immunity for the prevention of BRD and optimizing growth was reinforced. In addition to the cost of treating sick calves, the economic consequences of BRD include increased mortality, reduced growth, increased age at first calving (AFC) and increased dystocia at first parturition (Stanton et al., 2012). With that said, it has been difficult to elucidate any direct relationship between calfhood health and milk production. The impacts of calfhood disease primarily occur before first calving, by increasing AFC and reducing survival. It should be noted that for those heifers that survive and join the milking herd, they perform as well as their herdmates who remained healthy early in life. Overall, it seems clear that BRD has substantial effects on heifer survival and productivity, and has profound impacts on the economics, welfare and sustainability of the dairy industry (Bach, 2011). Further research should be conducted to investigate the association between calfhood disease and future performance, while taking into account AFC and survival. Considering the ongoing, worldwide struggles with neonatal disease in dairy calves, there is a clear need for an improved understanding of the unique features and challenges of the neonatal bovine immune system (Chase et al., 2008). Since calves are born immunologically naive, there is no chance to develop an adaptive immune response, before they face disease challenges in the neonatal period. Therefore, calves depend on passive and innate immunity to protect them from infectious disease during the early stages of life. While calves at birth most likely possess a majority of the components of a mature immune system, the cellular portions are naive and may be in a quiescent state. Furthermore, the soluble portions may exist in lesser concentrations than are necessary for an effective immune response. As described earlier, in the section on colostrum management, calves need to acquire passive immunity from their dam, shortly after birth, in order to survive. High levels of IgG, as well as other cellular components and cytokines that are present in colostrum, are essential for development of a calf’s immunity and protection against disease (Chase et al., 2008). During the first weeks of life, the level of maternal antibodies starts to decline, and the calf’s own adaptive immune system starts to develop. At a certain point, passive immunity drops below a level that is no longer protective against common pathogens. Unfortunately, this situation occurs before fully active immunological maturity, leaving what is known as a ‘window of susceptibility’ to infection (Fig. 2). To make matters worse, this timing often coincides with the age when calves may undergo stresses associated with management practices, such as weaning, moving, co-mingling and dehorning. The ideal circumstance would be to ensure continuity of immunity. In other words, circumstances should be set up to allow calves to generate an adaptive immune response before the passive immunity declines below the level of protection. Vaccination has been a primary method used to create an adaptive immune response. Yet, if maternal antibodies are present in sufficient quantity to block the vaccine antigen, or if the calf’s immune system is not sufficiently mature, there will be minimal detectible response to parenterally administered vaccines against the respiratory viruses associated with BRD (Windeyer et al., 2012). However, experimental challenge studies © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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have demonstrated varying levels of efficacy of vaccines administered via the intranasal route. Recently, a commercially available trivalent intranasal vaccine has shown a reduction in ultrasonographic lung lesions associated with BRD and has improved growth in young dairy calves (Ollivett et al., 2014a). Yet, various herd factors played a significant role in determining whether or not average daily gain was improved. Also, intranasal vaccination did not eliminate the risk of disease in that study. Identification of the opportune time, appropriate route, method of antigen presentation and other best practices for vaccination of neonatal animals remains as a substantial challenge for sustainable dairy production. As described earlier, there is no definitive evidence that the incidence of BRD in dairy calves has improved over the last few decades, and long-term consequences of this disease are becoming clearer. Furthermore, prompt and accurate diagnosis of BRD is often undermined by subtle and inconsistent clinical signs. The development and use of systematic calf health scoring systems have shown promise towards ameliorating the problems associated with generic definitions, as well as improving early detection rates and the initiation of treatment protocols (McGuirk, 2008). The most widely used system, the Wisconsin Calf Scoring Chart, divides the response to respiratory disease into 5 categories: body temperature, nasal discharge, cough, ocular discharge and ear position. One of the promising and encouraging developments in this field is the implementation and evaluation of the ability of clinicians using readily available, portable thoracic ultrasonography to diagnose the lung lesions associated with BRD in dairy calves (Buczinski et al., 2014). It is clear that methods of diagnosing lung lesions, and a better understanding of the effects of subclinical BRD, should be a priority for dairy researchers, and might serve to improve the welfare of dairy calves and the sustainability of the dairy industry in general.

Figure 2 Total immunoglobulin levels in a calf over time, starting at birth. The shaded area represents the period of increased susceptibility to infectious disease. Adapted from Morein et al., 2002; Chase et al., 2008. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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4.3  Sickness behaviour Sickness behaviour is defined as a coordinated set of responses to an infectious or inflammatory condition (Johnson, 2002). For example, the analysis of lying behaviour of affected animals by visual observation of video recordings has shown promise for the early detection of illness in dairy calves (Borderas et al., 2008). More recently, accelerometers have been used to objectively measure specific aspects of lying patterns, without the labour of analysing large quantities of video. Automated measures of lying behaviour that have been validated in the dairy calf consist of total lying time, total standing time, number and duration of individual lying and standing bouts, and the laterality of the lying position (Bonk et al., 2013). Yet, the effect of specific diseases on lying behaviour in dairy calves has not been extensively studied. An earlier study showed that a low-dose injection of bacterial endotoxin does appear to alter lying patterns (Borderas et al., 2008). In a recent investigation, the relationships between clinical parameters, diagnostic ultrasonography and lying behaviours in pre-weaned dairy calves from a herd with a high prevalence of endemic respiratory disease were studied (Ollivett et al., 2014b). Total lying time was significantly affected by fever and age. Monitoring lying time in pre-weaned dairy calves might have a place in identifying febrile animals, requiring individual examination and possible intervention. It is possible that automated tools, such as accelerometers, may be able to detect behavioural changes during the early stage of BRD, thereby enhancing our ability to identify and manage disease. Further studies are needed to determine if identification of such animals results in better outcomes as compared to traditional methods of disease identification. Another approach to the measurement of physiological, behavioural and production indicators on individual calves involves monitoring the data collected from automated milk feeding systems for group-housed pre-weaned calves. Such systems offer the benefits of reallocation of labour, earlier socialization of calves and an easy way to deliver more milk. However, concerns include increased risk for morbidity and mortality, as well as delays in disease detection. Software programs in the automated milk feeding systems should be able to assist in the detection of sick calves by flagging calves when there has been a large reduction in milk intake or large changes in drinking speed. However, the early simplistic algorithms used in these systems did not prove to be any more sensitive or timely than a human observer, and often missed detecting sick calves altogether. Recent research has focused on different algorithms to examine feeding behaviour that could improve the sensitivity and timeliness of detecting sick calves (Knauer et al., 2015). Although several feeding behaviours differ between healthy and sick calves, drinking speed and unrewarded visits to the feeder offer the greatest potential to be useful as indicators of morbidity in group-housed, computer-fed calves. Further research should pursue validation and improvement of these findings. While changes in lying activity and feeding behaviour may be likely to provide the most practical behavioural indicators of disease, sickness behaviour includes a number of other behavioural changes. These changes include a general reduction in behaviours less critical to survival, including social behaviour, grooming and exploration (Weary et al., 2009). Borderas et al. (2008) reported that calves exposed to a low dose of bacterial endotoxin have been found to spend less time eating hay and self-grooming. Cramer and Stanton (2015) assessed the relationship between exploratory behaviour and disease, and found that calves diagnosed with BRD or diarrhoea were less likely to approach a stationary human or a novel object. While further work is needed to validate behavioural indicators © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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of disease, these results suggest that there may be a wide range of subtle behavioural cues that should be considered to aid in screening for disease.

4.4  Genetic approaches to improved calf health and survival With such a significant portion of the cost of production going towards heifer rearing, it is remarkable that such limited emphasis has been placed on calf health and survival as economically important traits included in genetic selection indices. Nearly a decade ago, a large retrospective study determined that there is genetic variation among sires for the survival of their offspring (Henderson et al., 2011a). A companion investigation estimated the heritability of BRD, bloat and umbilical disease to be 0.09, 0.04 and 0.14, respectively (Henderson et al., 2011b). Although these heritabilities are generally low, it is clear that significant variation existed between Holstein sires, making selection for disease resistance and improved calf survival possible, with gains that are independent of effects of birth weight. More complete and accurate data collection by dairy producers would be necessary in order to develop accurate genetic evaluations for calf health and survival. Another genetic-based approach to enhancement of immune function, known as ‘Immunity+ Sires’, has shown considerable promise for improvement in measures of health and performance (Wagter et al., 2000; Mallard et al., 2011). This programme is founded upon phenotypic tests for specific assessment of antibody-mediated immune response (AMIR) and cell-mediated immune response (CMIR) of sires and their daughters. In the case of calves, this approach has demonstrated that cows with a high AMIR profile produced colostrum containing higher levels of IgG and beta-lactoglobulin (b-LG), suggesting that feeding colostrum from these cows could reduce the incidence of FPT in calves (Fleming et al., 2016). In addition, there could be potential protective effects of IgA at the mucosal surface of the intestines. Related to this concept, it is noteworthy that the health benefits of whey proteins are under investigation in humans. Colostrum from high AMIR cows may provide a more efficient source of ingredients for future manufacturing of natural health products for human consumption. Future research is required to determine if b-LG plays a role in preventing septicaemia, diarrhoea and respiratory infections in calves after birth, and if this molecule could be used to compensate for the lack of protective Ig in colostrum. Breeding for cattle with high AMIR may lead to the production of better quality colostrum to improve passive protection in young calves.

5  Housing considerations Housing strategies and facilities for the pre-weaned dairy calf are diverse. In many cases, the welfare of the calf may depend to a greater extent on management, cleanliness, and farm staff attentiveness than basic housing characteristics, such that different farms may implement vastly different approaches to calf housing with similar success. It is understood, however, that the housing environment for dairy calves can have broad implications for welfare, including growth and health, comfort and behavioural expression.

5.1  Social housing Individual housing for calves has traditionally been recommended to minimize the spread of disease and allow monitoring of individual calves, yet there is little evidence to suggest © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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that housing calves in small, well-managed groups increases the risk of disease. However, housing calves in larger groups of over 10 calves may be associated with a greater risk for respiratory disease (Svensson and Liberg, 2006). Apart from group size, pen stocking density and environmental factors such as ventilation and pen cleanliness are likely to be critical predictors of calf health. Stocking rate impacts airborne pathogen load, and lower stocking rate reduces respiratory disease (reviewed by Gorden and Plummer, 2010). With the increasing adoption of computerized calf feeding technology, it is becoming increasingly feasible and common to house calves in large, dynamic groups. Management strategies to allow for sufficient space per calf (e.g. 2.3–2.8 m2/calf; Gorden and Plummer, 2010), appropriate ventilation and effective disease monitoring is of importance to calf welfare in these housing conditions. Research in recent years has provided evidence of a number of short-term and longerterm benefits of social housing from a behavioural standpoint. Calves reared in pairs or groups have been noted to consume more solid feed (De Paula Vieira et al., 2010; Phillips, 2004), and have more frequent meals of both milk and solid feed (Miller-Cushon and DeVries, 2015), which is likely due to social facilitation of feeding or social learning. Importantly, early social contact allows for normal social interactions, including play (Duve et al., 2012) and social bonding (Færevik et al., 2006). Early social contact may play a critical role in the ability of the calf to cope with novel situations. Socially reared calves appear to be less reactive when faced with a novel environment and social separation (De Paula Vieira et al., 2012) and struggle less in response to restraint (Duve et al., 2012). The effects of early social contact on the behavioural and cognitive development of the calf may be critical for longer-term welfare. Calves reared in pairs have been found to perform better in the reversal learning stage of a cognitive task (Gaillard et al., 2014), suggesting increased behavioural flexibility in calves with early social enrichment. Although no work to date has linked cognitive ability of adult cows to early life experiences, evidence of early cognitive deficits in individually reared calves is important, and may well influence their ability to adapt to novel management scenarios throughout their life. While understanding of longer-term effects on cognitive development is currently lacking, there is evidence of longer-term effects of social rearing on social development. Compared with calves reared individually, calves previously reared in social groups have been found to be more successful in competitive feeding scenarios (Duve et al., 2012) and may rank higher in a social hierarchy (Broom and Leaver, 1978). By contrast, calves reared in social isolation exhibit more agonistic social behaviours and may adapt less well to a social environment (Veissier et al., 1994). Although rearing calves in social environments is likely to benefit welfare, challenges remain with effectively implementing group-housing. Competition for access to feed is likely unavoidable in group-housing scenarios, as competitive displacements at the feeder are evident even in small groups of only 2–3 calves when feeding stations are limited (von Keyserlingk et al., 2004; Miller-Cushon et al., 2014a). A greater age and size range within larger pens can prompt increased competition (Hepola, 2003; Faerevik et al., 2010), suggesting that stable groups are likely to reduce competition and agonistic social interactions compared with dynamic groups. Interestingly, there is some evidence that calves in large groups (of 8–16) may be displaced from the feeder less frequently than calves housed in smaller groups of 4 (Færevik et al., 2007), suggesting that calves may learn to avoid agonistic interactions in a large stable social group. Minimizing competition early in life may have important longer-term consequences, as there is evidence that competitive displacements at the feeder, as well as greater rates of intake and feeding © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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patterns associated with competitive pressure, persist post-weaning in calves previously reared in a more competitive group with a limited number of feeding stations (MillerCushon et al., 2014a). Although competition can, in some cases, be reduced or prevented through feeder design (Jensen et al., 2008), the tendency for calves to engage in synchronized feeding when possible (Miller-Cushon et al., 2014a; Miller-Cushon and DeVries, 2015) suggests that feeding systems which allow for social feeding may better accommodate the natural behaviour of the calf. Although it is concerning that competition can negatively affect intake and growth, at least in the short-term (Miller-Cushon et al., 2014a; von Keyserlingk et al., 2004), it may be that preference for social feeding outweighs desire to avoid competition at the feeder, especially if agnostic interactions are minimal and calves simply take turns feeding, as is sometimes observed (Miller-Cushon et al., 2014a). There is some evidence that, when offered a choice of feeding locations, pair-housed calves prefer to feed alongside a familiar calf than in isolation (Miller-Cushon and DeVries, 2015), but little is known about the social feeding preferences and motivation to avoid competition of calves housed in larger groups.

5.2  Housing environment Calf performance and welfare are influenced by aspects of the housing environment, including temperature, ventilation, bedding surfaces, and space allowance. Temperatures outside the thermoneutral zone of the calf pose challenges both for health and growth, and for comfort. In much of North America, summer weather can create conditions of heat stress for livestock. Cooling with fans has been found to improve weight gain and feed efficiency of calves housed in summer temperatures ranging from 8 to 34°C (Hill et al., 2011). Relatively little work to date has explored effects of heat stress on either behaviour of the calf early in life or longer-term growth and performance. When temperatures drop below the lower critical temperature (15°C for neonatal calves; NRC, 2001), appropriate bedding is important to reduce heat loss through conduction. Hill et al. (2011) reported that lying posture was influenced by bedding, with calves lying on sand tucking their legs under their bodies, whereas calves bedded on straw were more likely to rest with their legs exposed and nestle into bedding. In a survey of naturally ventilated calf barns in North America during winter, Lago et al. (2006) reported that a higher nesting score, indicating that the ability of the calf to nestle into the bedding was associated with reduced risk of respiratory disease. Lying time and preference for lying location can be considered indicators of comfort in adult dairy cows, and have similarly been evaluated in dairy calves in response to different bedding surfaces. For example, greater lying time has been reported in calves bedded on sawdust as opposed to quarry stones (Sutherland et al., 2014). Camiloti et al. (2012) reported that when calves were provided pens divided into one area with dry sawdust and the second area with either wet sawdust (ranging from 74 to 29% DM) or concrete, much less time was spent lying on the wet sawdust than on dry sawdust, and calves never chose to lie down on the concrete. Preferences for soft, dry bedding may be due to the ability to nest, comfort when lying down, or warmth. Hänninen et al. (2005) described a positive correlation between total lying time and average daily weight gain in pre-weaned calves, suggesting that adequate rest is important for the performance of the growing calf. Space allowance for dairy calves influences behaviour and, if insufficient, can reduce welfare. In groups of 3 calves, active movements were restricted when less space was © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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provided (1.0 or 1.5 vs. 2.0 m2/calf; Sutherland et al., 2014), and, similarly, active play behaviour was reduced in both individually housed and group-housed calves when less space was provided (1.35 vs. 4.0 m2/calf; Jensen et al., 1998). Further, group-housed calves in general have access to a larger total area than individually housed calves, and Jensen et al. (1998) reported that group-housed calves were more active than individually housed calves when space allowance per calf was similar.

6  Feeding management 6.1  Milk feeding The early growth, performance and behaviour of the pre-weaned calf are highly subject to the milk feeding programme. Whereas conventional feeding regimes have long recommended encouraging early solid feed intake through limiting milk allowance, it is increasingly accepted today that providing greater amounts of milk early in life can benefit performance and welfare of the calf. According to conventional restricted feeding programmes, dairy calves are provided milk or milk replacer at a rate of 4–5 L/d, whereas calves with ad libitum access to milk will consume 2–3 times that amount (Appleby, 2001; Jasper and Weary, 2002). Calves fed restricted amounts of milk have substantially reduced weight gain, and may be prone to illness as a result of compromised immune function when nutrient supply is limiting (Nonnecke et al., 2003). Further, there is evidence of a relationship between plane of nutrition and growth early in life and longer-term reproductive and lactation performance (Soberon et al., 2012; Gelsinger et al., 2016), suggesting that early life nutrition has both immediate and longer-term impacts on the performance of the calf. The effects of milk feeding programme on calf performance and welfare have been well reviewed previously (Khan et al., 2011b). The approach to implementing ad libitum milk feeding programmes, or any accelerated feeding programme that increases milk allowance over a conventional restricted rate, varies between farms. In many cases, use of automated milk feeders simplifies feeding of grouphoused calves on accelerated feeding programmes. As discussed earlier, these feeders provide the advantage of monitoring individual intake of group-housed calves and provide data that may assist in identifying sick animals. In other cases, higher milk allowances may be provided manually via more frequent, or larger, daily milk deliveries. There is some evidence that provision of large, less frequent meals may be less desirable than providing more frequent access to milk. Hulbert et al. (2011) reported that consolidating daily milk allowance from two daily meals into a single meal had no effect on average daily gain, but was likely a stressor for the calf, based on changes in immune response. Further, there is some evidence that increasing milk allowance without adjusting feeding frequency may affect glucose metabolism and reduce insulin sensitivity (Bach et al., 2013). Milk feeding programmes have marked effects on the behaviour of the calf. Providing ad libitum access to milk allows for more natural suckling behaviour of the calf, with calves typically distributing feeding activity over the course of the day in frequent meals (e.g. 4–10 meals per day; Appleby, 2001; Miller-Cushon et al., 2013), resembling the behaviour of a suckling calf (de Passillé, 2001). When milk supply and, consequently, feeding time is restricted, calves engage in frequent bouts of non-nutritive sucking (de Passillé, 2001; Miller-Cushon et al., 2013a). Further, the general behaviour of the calf is largely influenced © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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by plane of nutrition. Calves fed less milk exhibit less play behaviour (Krachun et al., 2010; Duve et al., 2012), vocalize more (Thomas et al., 2001) and spend less time lying and have frequent unrewarded visits to the feeder (De Paula Vieira et al., 2008). These behavioural changes associated with restricted milk feeding can easily be interpreted as indicators of hunger, suggesting that conventional, restricted milk feeding programmes likely impair calf welfare. Apart from milk feeding allowance, the method of milk feeding has implications for calf welfare. The motivation to suckle exists apart from hunger (Hammell et al., 1988) and the action of sucking, apart from ingesting milk, stimulates the release of digestive hormones that may contribute to satiety (de Passillé et al., 1993). When calves are provided their milk by bucket, rather than via an artificial teat, they are likely to engage in non-nutritive sucking (Jensen and Budde, 2006). In group-housed calves, non-nutritive sucking can be expressed as cross-sucking behaviour, which poses both immediate and longerterm health and welfare concerns, as this behaviour can persist post-weaning (Keil and Langhans, 2001). Thus, provision of milk via a teat satisfies a behavioural need to suck, may impact digestion and satiety of the calf, and reduces the development of an abnormal and potentially harmful behaviour.

6.2  Provision of solid feed to pre-weaned calves The early feeding programme of the dairy calf involves the provision of solid feed, including a highly digestible grain concentrate and, in some cases, forage. It is well established that early intake of concentrate is important for rumen development and, consequently, the ability of the calf to digest and utilize nutrients from solid feed during and after weaning. In particular, the fermentation of carbohydrates produces butyrate, which triggers the development of rumen papillae (Warner et al., 1956; Sander et al., 1959). Hay, on the other hand, is lower in nutrients and is generally considered to be less critical for rumen development. However, offering physically effective forage to pre-weaned calves has been found to provide a number of benefits, including improving rumen environment through increasing rumen pH (Khan et al., 2011a), and increasing digestibility of nutrients (Montoro et al., 2013) and feed efficiency (Coverdale et al., 2004). Interestingly, there is some evidence that hay intake may be satisfying for the calf from a behavioural standpoint, as it is associated with reduced non-nutritive oral behaviour (Castells et al., 2012). Further, calves voluntarily select a proportion of hay in their diet, in some cases even selectively consuming hay particles from a mixed diet containing both concentrate and hay (MillerCushon et al., 2013b). Given the importance of early solid feed intake for calf performance, some attention has been paid to the palatability of concentrate components. It is established that calves exhibit preferences for certain ingredients in pairwise preference tests (Montoro and Bach, 2012; Miller-Cushon et al., 2014b), and restriction to a less preferred diet may negatively impact intake, at least over a short period of time (Miller-Cushon et al., 2014b). However, it is not well understood whether palatability of feed is likely to influence intake when choice is not a factor. Montoro et al. (2011) reported that providing a starter ration with the same flavour as milk replacer resulted in a slight increase in intake in calves with low intake before weaning, suggesting that feed familiarity may influence acceptance of solid feed when calves are reluctant to begin consuming it. There is growing evidence that early calf feeding programmes have potential to influence feeding behaviour into the post-weaning stage. Feed sorting behaviour is a © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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welfare concern for adult cattle, as it results in an unbalanced intake of nutrients and has potential to impair rumen health and impair performance (DeVries et al., 2008). The sorting behaviour of calves provided a mixed diet of chopped hay and concentrate has been observed before weaning (Miller-Cushon et al., 2013b), and the extent of feed sorting into the post-weaning period appears to depend on early experience. MillerCushon et al. (2013b) reported that calves provided the opportunity to sort during the milk feeding stage, through the provision of a mixed diet, continued to sort into the postweaning stage, whereas calves provided separate feed components did not begin to sort during the 6 weeks that they were followed post-weaning. The welfare implications of feed sorting early in life are not well understood, but there is potential for feed sorting early in life to have both immediate negative effects, if there is an impact on rumen health, and longer-term effects, if early experience continues to influence behaviour into adulthood. However, it is also important to consider that, in some cases, feed sorting can be beneficial. Adult cattle experiencing a bout of low rumen pH may sort in favour of longer particles to attenuate this condition (DeVries et al., 2008), yet it is not clear whether feed sorting may have any similar beneficial outcome for younger calves.

6.3  Weaning calves from milk Weaning of the dairy calf from milk to solely a diet consisting only of solid feed is a critical and likely stressful transition, during which the calf may experience impaired growth. Whereas calves have been reported to nurse their dam for 7–14 months in a semi-wild herd (Reinhardt and Reinhardt, 1981), calves are typically weaned after only 6 to 8 weeks of life on modern dairy farms (Vasseur et al., 2010). Weaning is accompanied by behavioural signs of stress, such as vocalizations (De Paula Vieira et al., 2010), as well as suppression of innate immune responses (Hulbert et al., 2011b). It is well established that early acceptance and intake of solid feed is critical for rumen development and supports consistent weight gain through milk weaning (Terré et al., 2007). The welfare and performance of the calf during the weaning transition therefore depends primarily on the extent to which the calf has begun consuming solid feed before the removal of milk, which can be influenced by the timing and method of removal of milk, as well as by social factors. Conventional milk feeding programmes, with low milk allowance, were intended to encourage early solid feed intake and facilitate early weaning of calves. However, with the increasing implementation of accelerated milk feeding programmes in recent years, calves are consuming less solid feed early in life (Jasper and Weary, 2002), and weaning must be managed carefully to encourage solid feed intake and support consistent weight gain. Calves weaned abruptly from milk are likely to experience reduced growth, whereas calves weaned over a longer period of time (10 days or more) consume more solid feed before removal of milk and gained more weight (Sweeney et al., 2010). Weaning later in life accomplishes a similar goal of supporting increased intake before weaning and improved weight gain through weaning (Eckert et al., 2015). Starter intake varies considerably between calves, and weaning based on individual intake may be a promising approach to improve calf performance and reduce hunger (de Passillé and Rushen, 2016), although individualized weaning programmes are unlikely to be feasible on large farms relying on manual feeding. As discussed above, social housing for dairy calves encourages increased solid feed intake, which can translate into improved performance through weaning. Likely due to greater solid feed intake early in life, group-housed calves have been observed to gain © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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weight more consistently through the weaning period, whereas individually housed calves experienced a check in their growth (Chua et al., 2002; Miller-Cushon and DeVries, 2015). Pair-housed calves also vocalize less in response to weaning (De Paula Vieira et al., 2010), possibly due to either increased early solid feed intake and reduced hunger in response to removal of milk, or social buffering of response to this potentially stressful event. Social effects on solid feed intake are particularly influential in calves provided greater milk allowances (Jensen et al., 2015), suggesting that social grouping is an effective step towards facilitating weaning of calves on accelerated milk feeding programmes.

7  Managing weaned calves Reducing age at first calving, without compromising body weight at that time, has financial benefits for dairy producers, as it reduces the number of replacements needed as well as the number of days on feed for replacements. Further, growth efficiency in young dairy cattle remains very high, particularly up to 6 months of age. Thus, once dairy calves are successfully weaned off milk, the goal in rearing them should be to continue to maintain a high level of growth, such that they achieve puberty early, are of sufficient size to be bred by 12–14 months of age, and thus calve at 22–23 months of age at 80–90% of mature body weight. Feeding programmes for replacement heifers need to be designed to promote such desired growth. While there is vast knowledge on how various feed types contribute to meeting nutrient requirements for growth, dairy producers are still challenged in achieving that growth, in particular, consistency in growth across their dairy replacements. In this section of the chapter, the focus will be placed on the specific role that feeding management has on the health and welfare of calves after weaning, with particular emphasis on methods of feed delivery, the amount of feed provided, and feeding space availability.

7.1  Feeding delivery methods Traditional feeding practices for weaned dairy calves have included the addition of forage (typically dry forage) to a grower concentrate up to about 6 months of age, after which common practice would be to transition calves over to a silage-based ration. During those first few months post-weaning, the grain concentrate portion of the diet has traditionally, as with calves, been provided separate from the roughage or on top of the roughage (‘top dressing’). In this feeding practice, the amount of concentrate is typically fixed, while the forage (provided ad libitum) intake is variable. The net result of this is variable total DMI, which may in turn lead to inconsistent and variable growth rates. Researchers have recently demonstrated that intake consistency and feeding patterns are improved when replacement heifers are fed a mixed ration (i.e. total mixed ration; TMR) as compared to having their feed components provided separately. For example, DeVries and von Keyserlingk (2009a) demonstrated that replacement dairy heifers will consume a large proportion of the grain component of their diet in the time period immediately after feed delivery when given a choice of ration components, or when provided grain concentrate top-dressed on hay. Alternatively, those researchers found that heifers provided a TMR had smaller meals after feed delivery, exhibiting less of a ‘slug feeding’-type response. Greter et al. (2010a) reported similar feeding patterns in heifers provided with concentrate top-dressed on haylage as compared to those fed a © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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TMR. Not only does feeding method influence the timing and size of meals, but also the composition of feed consumed. Both DeVries and von Keyserlingk (2009a) and Greter et al. (2010a) demonstrated that the amount of sorting against forage, and for concentrate, in replacement dairy heifers is reduced in those fed TMR. Thus, providing a TMR to young, dairy heifers limits undesirable variations in feeding patterns (i.e. variation in amount of feed consumed across the day and also in the composition of the feed consumed), which may result in large post-prandial drops in rumen pH, as demonstrated in young dairy cattle (Quigley et al., 1992; González et al., 2008). Part of this feeding response to concentrate, provided separate from forage, may be due to the desire to consume the concentrate, in fear of not being able to at a later time. Researchers have found that feeding concentrate apart from forage creates more aggressive displacements and competition for feed, regardless of whether the concentrate is provided in a limited (Greter et al., 2010a) or ad libitum (González et al., 2008) amount. Increased competition, due to the desire to consume specific feeds at the bunk, is not limited only to situations where concentrate and forage are provided separately. Huzzey et al. (2013) recently demonstrated that replacement heifers, fed TMR varying in quality (low, medium and high energy), competed more for feed access when feed quality across the length of the feed bunk was nonuniform, as compared to when it was uniform (regardless of quality). As discussed earlier regarding milk-fed calves, the potential carry-over effect in learned behavioural patterns may be significant. Greter et al. (2010b) transitioned heifers fed TMR, or their feed components fed separately, to a common mixed ration. These researchers found that the feeding and competitive behaviour patterns heifers displaced while on the different feeding methods persisted after this dietary transition. These findings suggest not only that the heifers learned these behavioural patterns, but that these patterns became habitual and may potentially be difficult to extinguish in the long run. Similar results were also shown in a study by Groen et al. (2015), where dairy bull calves at 4–5 months of age were fed a dry TMR, containing either 85% concentrate and 15% chopped wheat straw or 70% concentrate and 30% chopped wheat straw. After 5 wk on these diets, calves were all switched to a silage-based TMR for 2 wk. During that time period calves previously fed the 70% diet continued to have a longer meal immediately after feed delivery. This was likely a reflection of the longer meal that those calves had while on their treatment diets, whereby they were also engaging in a greater degree of feed sorting (against the longer straw particles). Thus, data from these studies, as with that described earlier in this chapter for calves, suggests that providing replacement heifers with TMR diets that are designed to not only limit feed sorting, but also promote consistent intakes across the day are important for the short-term and long-term benefits of these animals.

7.2  Amount of feed provided Replacement dairy heifers have traditionally been provided high-forage, low-energy diets that are designed to control caloric intake and target a specific growth rate. Such diets are commonly fed in an ad libitum amount. Unfortunately, as with mature cattle, young dairy heifers will selectively consume (sort) their diets (Hoffman et al., 2006; Greter et al., 2008; DeVries and von Keyserlingk, 2009a,b), which then results in an imbalance of nutrients consumed relative to expectation. To prevent this imbalance, and to target a certain level of nutrient intake, various researchers have recommended the provision of a nutrient-dense diet fed in a limited amount (Hoffman et al., 2007; Zanton and Heinrichs, 2007). By targeting nutrient intake, © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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limit feeding can effectively control average daily gain in replacement heifers, as well as decreases faecal excretion, increase feed efficiency and even feed costs. It is interesting to note that in studies comparing limit-fed heifers to those fed a control diet, all fed for a similar level of ADG, when followed into first lactation, milk production of the limitfed heifers did not differ from those fed ad libitum (Hoffman et al., 2007; Zanton and Heinrichs, 2007). Unfortunately, despite these apparent benefits, limit feeding does pose welfare concerns for dairy heifers. These concerns stem from the variety of frustration and hunger-related behaviours (related to lack of satiety) observed in limit-fed heifers, including reduced eating time, increased inactive standing time (Kitts et al., 2011), increased vocalization levels, aggressive ‘reaching’ for feed (Hoffman, 2007) and increased levels of oral stereotypies, including tongue rolling, constant head nodding and bar biting/licking (Redbo et al., 1996; Redbo and Nordblad, 1997; Lindström and Redbo, 2000). Greter et al. (2015) demonstrated that the high motivation of limit-fed heifers to work for a low-nutritive feedstuff, as compared to those fed ad libitum, is related to the hunger and/or frustration due to lack of rumen fill and/or foraging substrate. A potential alternative to limit feeding would be to restrict the nutrient density of a TMR (Hoffman et al., 1996). Greter et al. (2008) tested this approach by adding different levels of a straw to a mixed ration and demonstrated that this method could help meet the natural foraging behaviour patterns of heifers. Similar results were seen by Kitts et al. (2011), who found that heifers with straw mixed into a TMR fed in a limited amount spent more time feeding, more time ruminating, less time unrewarded at the feed bunk and less time inactively standing. Unfortunately, one of the challenges with such an approach, seen in Greter et al. (2008) is an increase in the amount of feed sorting, which then once again results in heifers consuming more or less nutrients than desired for them. As an alternative to straw mixed into the TMR, another approach is to provide a lownutritive feedstuff (e.g. straw) alongside a limit-fed TMR. Greter et al. (2011) and Kitts et al. (2011) both demonstrated that providing straw, separate to a limit-fed TMR, did have a positive impact on promoting rumen fill and reducing the negative behaviours associated with limit feeding. It is interesting to note that, likely due to the impact a nutrient-dense diet has on the rumen, limit-fed heifers have been shown to prefer long chopped straw to short chopped one (Greter et al., 2013). It is, thus, recommended to feed a low-nutritive feedstuff alongside a limit-fed TMR in an effort to meet the behavioural needs of heifers and to satisfy normal feeding behaviour and diurnal feeding patterns. It could be hypothesized that the behavioural effects of limit feeding could also be reduced by providing smaller portions of the ration more frequently throughout the day. Unfortunately, the data available does not support this idea. Greter et al. (2014) investigated the delivery of a limit-fed TMR 1x, 2x or 4x per day. These researchers found that limit-fed heifers, who provided their daily allotment of feed 1x spent more time feeding throughout the day, and also spent less time standing without eating, compared with the other feeding frequency treatments. It was hypothesized by these researchers that heifers limit-fed 1x/day experienced satiety, at least in the short term, following that large meal, whereas heifers fed smaller meals 2x or 4x spent less time feeding and may never have achieved sufficient rumen fill to reach satiety.

7.3  Feed space availability As with mature cattle, there is a continuing question regarding appropriate space availability for growing dairy heifers. While with mature dairy cattle, the effects of limited © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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feeding space may be more quickly apparent, with resultant impacts on outcomes such as intake, milk yield, milk composition, early lactation health and lameness, the direct implications for replacement heifers are slightly less obvious. That being said, there is some literature to support the idea that competition for feed appears to have similar (to mature cattle) behavioural effects, across feeding strategies, on replacement dairy heifers. These effects, in turn, may have productive, health and welfare impacts on those animals. A reduction in feeding time and a concomitant increase in feeding rate were observed by DeVries and von Keyserlingk (2009b) in ad libitum fed heifers exposed to high feed bunk competition (2 heifers/feeding place) compared with those with no feed bunk competition. Similar decreases in feeding time have been observed in studies with limit-fed heifers (Keys et al., 1978; Longenbach et al., 1999) and in heifers fed a highconcentrate diet ad libitum (González et al., 2008). Despite these reductions in time spent eating, no effects of feeding competition have been reported on DMI of ad libitum (DeVries and von Keyserlingk, 2009b; González et al., 2008) or limit fed (Keys et al., 1978; Longenbach et al., 1999) replacement heifers. Although total DMI appears to be resilient to reductions in feed space availability, dairy heifers compensate by eating faster, in large meals, and shifting their intake to other parts of the day (González et al., 2008; DeVries and von Keyserlingk, 2009b). As seen in mature cows, such feeding patterns (i.e. large, fast meals) may contribute to greater risk of ruminal acidosis, as shown by González et al. (2008). While the risks of sub-optimal rumen health are likely highest for high-concentrate diets, there is a potential risk for replacement heifers fed higher forage rations as well, particularly in situations where feed sorting is exacerbated. The most consistent impact of limited feed space availability on replacement dairy heifers is the variable effect it has on individual animals within a group. DeVries and von Keyserlingk (2009b) demonstrated that feed bunk competition increased day-to-day variation in meal duration, feeding time and meal size. Similarly, González et al. (2008) also found that the variability in feeding time tended to increase with competition. These researchers, as well as Longenbach et al. (1999), also found body weight within pens to be more variable, indicating a greater disparity between group members in their ability to maintain similar DMI. It is likely that, across these studies, the variability in feeding behaviour and weight gain observed with lower amounts of feeding space may be related to certain animals dominating the feed bunk after feed delivery and consuming excess DM, while others (i.e. subordinates) are not able to consume sufficient feed. Thus, these data would indicate that to maintain growth at a consistent level across all replacements heifers within a pen, as well as to promote good health and welfare, adequate feed bunk space is required so that all animals can feed simultaneously.

8 Summary Successfully rearing replacement dairy heifers to enhance welfare, profitability and sustainability remains a challenge on many farms. In this chapter, we have summarized the numerous recent advances in understanding how approaches to managing calf health, feeding and housing, both pre- and post-weaning, can have considerable impacts on the welfare of the calf. In outlining our current state of knowledge in these areas, we have also drawn attention to opportunities to improve welfare on-farm, including: © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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•• improved calf monitoring, early colostrum management, and refined approaches to intervention to enhance early calf vitality •• improved approaches to identify and manage both sickness and pain associated with routine procedures •• more widespread adoption of accelerated feeding programmes and social housing for dairy calves, as well as improved understanding of best practices for managing group-housed calves •• refinement of feeding practices to optimize growth and welfare of weaned heifers

9  Where to look for further information Without a doubt, and by a wide margin, the single best source of peer-reviewed information on the general subject of health and welfare of dairy calves and heifers is the Journal of Dairy Science from the American Dairy Science Association (ADSA), which can be found at: http://www.journalofdairyscience.org/. Additional information, particularly new scientific developments published in abstract form, are available in the proceedings of the ADSA meetings each year, which can be found at: https://www.adsa.org/. Following a major extension education meeting entitled Large Dairy Herd Management, hosted by the ADSA in Chicago, Illinois, there will be an electronic book publication from the proceedings of this meeting. This book will be published in 2017, and is entitled ‘Large Dairy Herd Management eBook Publication, Third Edition’. The book will have a section on ‘Calves and Replacements’, edited by R. E. James, of Virginia Tech University. Further information is available at: https://www.adsa.org/Publications/ LargeDairyHerdManagement.aspx. Based in the United States, there is an organization dedicated to the extension of information about calf and heifer rearing. This organization is named the ‘Dairy Calf and Heifer Association’, based in Madison, Wisconsin, USA. This organization holds an annual meeting each spring. The proceedings of this meeting, and other management information about rearing calves and heifers, is available at their website at: http://calfandheifer.org/ index.php. There are a number of electronic newsletters that focus on extension information related to dairy calves. The Veal Farmers of Ontario host an electronic newsletter, called the ‘Calf Care Corner’. This site focuses on timely issues related to the care of dairy replacement and veal calves. This newsletter is available at: http://calfcare.ca/. Two other examples of such electronic publications are the Calf Notes Newsletter published by Dr. Jim Quigley, and available at: http://www.calfnotes.com/index.html, as well as the Calving Ease Newsletter published by Dr. Sam Leadley, and available from Attica Veterinary Associates at: http:// atticavet.entrexp.com/orgMain.asp?orgid=11&storyTypeID=&sid=&.

10 References American Veterinary Medical Association Animal Welfare Division. 2014. Literature review on the welfare implications of the dehorning and disbudding of cattle. AVMA 1–9.

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Jensen, M. B., A. M. de Passillé, M. A. G. von Keyserlingk and J. Rushen. 2008. A barrier can reduce competition over teats in pair-housed milk-fed calves. J. Dairy Sci. 91: 1607–13. Jensen, M. B., L. R. Duve and D. M. Weary. 2015. Pair housing and enhanced milk allowance increase play behavior and improve performance in dairy calves. J. Dairy Sci. 98: 2568–75. Jensen, M. B., K. S. Vestergaard and C. C. Krohn. 1998. Play behaviour in dairy calves kept in pens: the effect of social contact and space allowance. Appl. Anim. Behav. Sci. 56: 97–108. Johanson, J., and P. Berger. 2003. Birth weight as a predictor of calving ease and perinatal mortality in Holstein cattle. J. Dairy Sci. 86: 3745–55. Johnson, R. 2002. The concept of sickness behavior: a brief chronological account of four key discoveries. Vet. Immunol. Immunopathol. 87: 443–50. Keil, N. M., and W. Langhans. 2001. The development of intersucking in dairy calves around weaning. Appl. Anim. Behav. Sci. 72: 295–308. Keys, J. E., R. E. Pearson and P. D. Thompson. 1978. Effect of feedbunk stocking density on weight gains and feeding-behaviour of yearling Holstein heifers. J. Dairy Sci. 61: 448–54. Khan, M. A., D. M. Weary and M. A. G. von Keyserlingk. 2011a. Hay intake improves performance and rumen development of calves fed higher quantities of milk. J. Dairy Sci. 94: 3547–53. Khan, M. A., D. M. Weary and M. A. G. von Keyserlingk. 2011b. Invited review: effects of milk ration on solid feed intake, weaning, and performance in dairy heifers. J. Dairy Sci. 94: 1071–81. Kitts, B. L., B. W. McBride, I. J. H. Duncan and T. J. DeVries. 2011. Effect of the provision of a lownutritive feedstuff on the behavior of dairy heifers fed a high-concentrate ration in a limited amount. J. Dairy Sci. 94: 940–50. Knauer, W. A., S. M. Godden, A. M. Dietrich and R. E. James. 2015. The use of precision dairy technologies to detect illness in group housed automatically-fed pre-weaned dairy calves. Proc. Am. Assoc. Bovine Practioners 48: 280. Krachun, C., J. Rushen and A. M. de Passillé. 2010. Play behaviour in dairy calves is reduced by weaning and by a low energy intake. Appl. Anim. Behav. Sci. 122: 71–6. Lindström, T., and I. Redbo. 2000. Effect of duration and rumen fill on behaviour in dairy cows. Appl. Anim. Behav. Sci. 70: 83–97. Lombard, J. E., F. B. Garry, S. M. Tomlinson and L. P. Garber. 2007. Impacts of dystocia on health and survival of dairy calves. J. Dairy Sci. 90: 1751–60. Longenbach, J. I., A. J. Heinrichs and R. E. Graves. 1999. Feed bunk length requirements for Holstein dairy heifers. J. Dairy Sci. 82: 99–109. Lundborg, G., E. Svensson and P. Oltenacu. 2005. Herd-level risk factors for infectious diseases in Swedish dairy calves aged 0–90 days. Prev. Vet. Med. 68: 123–43. Mallard, B. A., H. Atalla, S. Cartwright, B. C. Hine, B. Hussey, M. Paibomesai, K. A. Thompson-Crispi and L. Wagter-Lesperance. 2011. Genetic and epigenetic regulation of the bovine immune system: practical implications of high immune response technology. Proceedings of the National Mastitis Council 50th Annul Meeting of the National Mastitis Council, New Prague, MN, pp. 53–63. McGuirk, S. M. 2008. Disease management of dairy calves and heifers. Vet. Clin. N. Am-Food A. 24: 139–53. McGuirk, S. M., and M. Collins. 2004. Managing the production, storage and delivery of colostrum. Vet. Clin. North Am. Food Anim. Pract. 20(3): 593–603. Mee, J. F. 2004. Managing the dairy cow at calving time. Vet. Clin. North Am. Food Anim. Pract. 20: 521–46. Mee, J. F. 2008. Prevalence and risk factors for dystocia in dairy cattle: a review. Vet. J. 176: 93– 101. Meijering, A. 1984. Dystocia and stillbirth in cattle – a review of causes, relations and implications. Livestock Prod. Sci. 11: 143–77. Miller-Cushon, E. K., R. Bergeron, K. E. Leslie and T. J. Devries. 2013a. Effect of milk feeding level on development of feeding behavior in dairy calves. J. Dairy Sci. 96: 551–64. Miller-Cushon, E. K., R. Bergeron, K. E. Leslie, G. J. Mason and T. J. Devries. 2013b. Effect of early exposure to different feed presentations on feed sorting of dairy calves. J. Dairy Sci. 96: 4624–33. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

Ensuring the health and welfare of dairy calves and heifers151 Miller-Cushon, E. K., R. Bergeron, K. E. Leslie, G. J. Mason and T. J. DeVries. 2014a. Competition during the milk-feeding stage influences the development of feeding behavior of pair-housed dairy calves. J. Dairy Sci. 97: 6450–62. Miller-Cushon, E. K., and T. J. DeVries. 2015. Effect of social housing on the development of feeding behavior and social feeding preferences of dairy calves. J. Dairy Sci. 1–12. Miller-Cushon, E. K., C. Montoro, I. R. Ipharraguerre and A. Bach. 2014b. Dietary preference in dairy calves for feed ingredients high in energy and protein. J. Dairy Sci. 97: 1634–44. Misch, L., K. Lissemore, S. Millman and T. F. Duffield. 2007 An investigation into the practices of dairy producers and veterinarians in dehorning dairy calves in Ontario. Can. Vet. J. 48: 1249–54. Montoro, C., and A. Bach. 2012. Voluntary selection of starter feed ingredients offered separately to nursing calves. Livest. Sci. 149: 62–9. Morein, B., I. Abusugra and G. Blomqvist. 2002. Immunity in neonates. Vet. Immunol. Immunopathol. 87: 207–13. Murray, C. F., T. F. Duffield, D. B. Haley, D. L. Pearl, D. M. Veira, S. M. Deelen and K. E. Leslie. 2015c. The effect of Meloxicam NSAID therapy on the change in vigor, suckling reflex, blood gas measures, milk intake and other variables in newborn dairy calves. J. Vet. Sci Anim. Husbandry 3(4): 1–14. Murray, C. F., D. B. Haley, T. F. Duffield, D. L. Pearl, S. M. Deelen and K. E. Leslie. 2015b. A field study to evaluate the effects of meloxicam NSAID therapy and calving assistance on newborn calf vigor, improvement of health and growth in pre-weaned Holstein calves. Bov. Pract. 49(1): 1–12. Murray, C. F., and K. E. Leslie. 2013. Newborn calf vitality: risk factors, characteristics, assessment, resulting outcomes and strategies for improvement. Vet. J. 198: 322–8. Murray, C. F., D. M. Veira, A. Nadalin, D. M. Haines, M. L. Jackson, D. L. Pearl and K. E. Leslie. 2015a. Physiological and behavioural characteristics related to vitality and passive transfer of immunoglobulins in newborn Holstein calves. Can. J. Vet. Res. 2015; 79(2): 109–19. Neave, H. W., R. R. Daros, J. H. C. Costa, M. A. G. Von Keyserlingk and D. M. Weary. 2013. Pain and pessimism: dairy calves exhibit negative judgement bias following hot-iron disbudding. PLoS ONE 8: 8–13. Nonnecke, B. J., M. R. Foote, J. M. Smith, B. A. Pesch and M. E. Van Amburgh. 2003. Composition and functional capacity of blood mononuclear leukocyte populations from neonatal calves on standard and intensified milk replacer diets. J. Dairy Sci. 86: 3592–604. Ollivett, T. L., K. E. Leslie, T. Duffield, D. V. Nydam, J. Hewson, J. Caswell and D. F. Kelton. 2014a. A randomized controlled clinical trial to evaluate the effect of an intranasal respiratory vaccine on calf health, ultrasonographic lung consolidation, and growth in Holstein dairy calves. Proc. Am. Assoc. Bovine Practioners 47: 113–14. Ollivett, T. L., D. V. Nydam, T. Duffield, K. E. Leslie, G. Zobel, J. Hewson, J. Caswell and D. Kelton. 2014b. The effect of respiratory disease on lying behavior in Holstein dairy calves. PhD Dissertation. University of Guelph. Petrie, N. J., D. J. Mellor, K. J. Stafford, R. A. Bruce and R. N. Ward. 1996. Cortisol responses of calves to two methods of disbudding used with or without local anaesthetic. N. Z. Vet. J. 44: 9–14. Phillips, C. J. C. 2004. The effects of forage provision and group size on the behavior of calves. J. Dairy Sci. 87: 1380–8. Poulsen, K. P. and S. M. McGuirk. 2009. Respiratory disease in the bovine neonate. Vet. Clin. North Am. Food Anim. Pract. 25: 121–37. Quigley, J. D., T. M. Steen and S. I. Boehms. 1992. Posprandial changes of selected blood and ruminal metabolites in ruminating calves fed diets with or without hay. J. Dairy Sci. 75: 228–35. Redbo. I., Emanuelson, M., Lundberg, K. and Oredsson, N. 1996. Feeding level and oral stereotypies in dairy cows. Anim. Sci. 62: 199–206. Redbo, I., and A. Nordblad. 1997. Stereotypies in heifers are affected by feeding regime. Appl. Anim. Behav. Sci. 53: 193–202. Reinhardt, V., and A. Reinhardt. 1981. Natural sucking performance and age of weaning in zebu cattle (Bos indicus). J. Agric. Sci. 96: 309–12. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Sander, E. G., R. G. Warner, H. N. Harrison and J. K. Loosli. 1959. The stimulatory effect of sodium butyrate and sodium propionate on the development of rumen mucosa in the young calf. J. Dairy Sci. 42: 1600–5. Schuijt, G. 1990. Latrogenic fractures of ribs and vertebrae during delivery in perinatally dying calves: 235 cases (1978–88). J. Am. Vet. Med. Assoc. 197: 1196–1202. Soberon, F., E. Raffrenato, R. W. Everett and M. E. Van Amburgh. 2012. Preweaning milk replacer intake and effects on long-term productivity of dairy calves. J. Dairy Sci. 95: 783–93. Stafford, K. J., and D. J. Mellor. 2005. Dehorning and disbudding distress and its alleviation in calves. Vet. J. 169: 337–49. Stanton, A., D. Kelton, S. LeBlanc, J. Wormuth and K. Leslie. 2012. The effect of respiratory disease and a preventative antibiotic treatment on growth, survival, age at first calving, and milk production of dairy heifers. J. Dairy Sci. 95: 4950–60. Stock, M. L., S. L. Baldridge, D. Griffin and J. F. Coetzee. 2013. Bovine dehorning: assessing pain and providing analgesic management. Vet. Clin. North Am. Food Anim. Pract. 29: 103–33. Sutherland, M. A., G. M. Worth and M. Stewart. 2014. The effect of rearing substrate and space allowance on the behavior and physiology of dairy calves. J. Dairy Sci.97: 4455–63. Svensson, C., and P. Liberg. 2006. The effect of group size on health and growth rate of Swedish dairy calves housed in pens with automatic milk-feeders. Prev. Vet. Med. 73: 43–53. Sweeney, B. C., J. Rushen, D. M. Weary and A. M. de Passillé. 2010. Duration of weaning, starter intake, and weight gain of dairy calves fed large amounts of milk. J. Dairy Sci. 93: 148–52. Terré, M., M. Devant and A. Bach. 2007. Effect of level of milk replacer fed to Holstein calves on performance during the preweaning period and starter digestibility at weaning. Livest. Sci. 110: 82–8. Thomas, T. J., D. M. Weary and M. C. Appleby. 2001. Newborn and 5-week-old calves vocalize in response to milk deprivation. Appl. Anim. Behav. Sci. 74: 165–73. Trotz-Williams, L., K. Leslie and A. Peregrine. 2008. Passive immunity in Ontario dairy calves and investigation of its association with calf management practices. J. Dairy Sci. 91(10): 3840–9. USDA. 2007. Dairy 2007, Heifer Calf Health and Management Practices on U.S. Dairy Operations, 2007. USDA: APHIS: VS, CEAH. Fort Collins, CO, pp. 1–168. Van Donkersgoed, J., C. S. Ribble, L. G. Boyer and H. G. Townsend. 1993. Epidemiological study of enzootic pneumonia in dairy calves in Saskatchewan. Can. J. Vet. Res. 57: 247–4. Vasseur, E., F. Borderas, R. I. Cue, D. Lefebvre, D. Pellerin, J. Rushen, K. M. Wade and A. M. de Passillé. 2010. A survey of dairy calf management practices in Canada that affect animal welfare. J. Dairy Sci. 93: 1307–15. Veissier, I., V. Gesmier, P. Le Neindre and J. Y. Gautier. 1994. The effects of rearing in individual crates on subsequent social behaviour of veal calves. Appl. Anim. Behav. Sci. 41: 199–210. Vermorel, M., C. Dardillat, J. Vernet, Saido and C. Demigné. 1983. Energy metabolism and thermoregulation in the newborn calf. Ann. Vet. Res. 14: 382–9. von Keyserlingk, M. A. G., L. Brusius and D. M. Weary. 2004. Competition for teats and feeding behavior by group-housed dairy calves. J. Dairy Sci. 87: 4190–4. Wagter, L. C., B. A. Mallard, B. N. Wilkie, K. E. Leslie, P. J. Boettcher and J. C. M. Dekkers. 2000. A quantitative approach to classifying Holstein cows based on antibody responsiveness and its relationship to peripartum mastitis occurrence. J. Dairy Sci. 83: 488–98. Waltner-Toews, D., S. W. Martin and A. H. Meek. 1986a. Dairy calf management, morbidity and mortality in Ontario Holstein herds. 3. Assoc. Manage. Morb. Prev. Vet. Med. 4: 137–58. Waltner-Toews, D., S. W. Martin and A. H. Meek. 1986b. Dairy calf management, morbidity and mortality in Ontario Holstein herds. 4. Assoc. Manage. Morb. Prev. Vet. Med. 4: 159–71. Warner, R. G., W. P. Flatt and J. K. Loosli. 1956. Dietary factors influencing the development of the ruminant stomach. J. Agric. Food Chem. 4: 788–92. Weary, D. M., J. M. Huzzey and M. A. G. von Keyserlingk. 2009. Board-invited review: using behavior to predict and identify ill health in animals. J. Anim. Sci. 87: 770–7.

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Ensuring the health and welfare of dairy calves and heifers153 Winder, C. B., S. J. LeBlanc, D. B. Haley, K. D. Lissemore, M. A. Godkin and T. D. Duffield. 2015. Practices for the disbudding and dehorning of dairy calves in the province of Ontario. Proc. Am. Assoc. Bovine Practioners 48: 284. Windeyer, M., K. Leslie, S. Godden, D. Hodgins, K. Lissemore and S. LeBlanc. 2012. The effects of viral vaccination of dairy heifer calves on the incidence of respiratory disease, mortality, and growth. J. Dairy Sci. 95: 6731–9. Windeyer, M., K. Leslie, S. Godden, D. Hodgins, K. Lissemore and S. LeBlanc. 2014. Factors associated with morbidity, mortality, and growth of dairy heifer calves up to 3 months of age. Prev. Vet. Med. 113: 231–40. Zanton, G. I., and A. J. Heinrichs. 2007. The effects of controlled feeding of a high-forage or highconcentrate ration on heifer growth and first-lactation milk production. J. Dairy Sci. 90: 3388–96.

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Part 2

Nutrition of dairy cattle

Chapter 7 The rumen microbiota and its role in dairy cow production and health Anusha Bulumulla, Mi Zhou and Le Luo Guan, University of Alberta, Canada 1 Introduction 2 Diversity and function of rumen microbiota 3 Factors influencing composition of rumen microbiota 4 Current trends and innovations in studying the rumen microbiome: ‘omics’ approaches 5 Current trends and innovations in studying the rumen microbiota: linkage with host phenotypes 6 Altering rumen function by manipulating microbiota 7 Knowledge gaps and future directions 8 Conclusions 9 Where to look for further information 10 References

1 Introduction Ruminants are characterized by their capacity for pre-gastric anaerobic fermentation in the rumen (foregut), which harbors a variety of microbes, including bacteria, archaea, protozoa and fungi. The complex association of different microbes acts synergistically for the conversion of cellulosic feed into volatile fatty acids (VFAs) and proteins that fulfil the nutrient requirements of the animals (Frey et al., 2010). Rumen microbiology research began in the 1950s, when Dr Robert Hungate used anaerobic culture techniques to explore this complex microbial ecosystem (Hungate, 1960). Through the twentieth century, culture-based techniques were the principal tool in rumen microbiology research, but these methods explored only a small proportion of the total rumen microbial population. The major advances in our knowledge of rumen microbes in the twenty-first century have been achieved by the use of culture-independent nucleic acid-based technologies and genomics. In particular, a comprehensive understanding of rumen microbial diversity together with advances in phylogenetic studies has marked a

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major milestone in rumen microbiology. The analysis of the 16S rRNA gene, a conserved microbial gene marker, has led to the discovery of novel and unculturable bacterial and archaeal species. Recent applications in molecular biology such as metagenomics analysis have allowed a more comprehensive understanding of this unique ecosystem, revealing the diversity of the microbial community, the microbial–microbial relationship, and the functional potential of the microbiome as well as their role in microbial–host relationship. Research into rumen microbial diversity and function has attracted attention in the past few decades because of the importance of rumen microbiology to many economically important traits and to the environmental impact of dairy herds. With an increasing human population and decreasing arable land, it is necessary to change livestock management in various ways, such as increasing herd density and increasing the use of grain in animal feed. These practices have led to increased environmental impacts as well as animal health issues (Yeoman and White, 2014). Currently, a significant amount of the cereal grain (wheat, barley) produced in the world that is suitable for human consumption is actually used in livestock farming, most notably in the cattle industry (Eisler et al., 2014), to enhance production through improved feed efficiency and growth. However, the cereal grain-based readily fermentable diet increases metabolic disorders in cattle such as subacute ruminal acidosis (Gao and Oba, 2014) and also increases the incidence of welfare-related issues such as lameness (Ventura et al., 2014). Given the competing demands for cereals as food or feed over the past few decades, it is important to increase meat and milk production while ensuring animals are healthy and minimizing the use of human-suitable food in their diet (Eisler et al., 2014). Knowledge about feed utilization and the digestive efficiency of rumen microbiota could therefore provide possible ways to manipulate microbial composition and function in the rumen, leading to higher feed efficiency and less negative metabolic and environmental effects. In this chapter, we will focus principally on the knowledge of rumen microbiota achieved to date, recent findings about its role in cattle feed efficiency and metabolic dysfunction, and potential strategies to improve rumen function for better production and health through manipulation of rumen microbiota.

2  Diversity and function of rumen microbiota Rumen microbiology research has evolved over the last decade to produce greater understanding of diversity, metabolic functions and different interactions of rumen microbiota. This has been possible because of the use of molecular biology techniques. To date, hundreds to thousands of microbial phylotypes have been identified from various rumen systems using the culture-independent molecular-based approaches (Brulc et al., 2009; Henderson et al., 2015). This huge diversity in microbial composition suggests that the rumen microbiome (the collective genomes of rumen microbiota) contains 100 times more genes than the host animal (McSweeney and Mackie, 2012), provides genetic and metabolic capabilities to digest fibres and provides host animals with nutrients and energy. Molecular microbial ecology studies have allowed the identification of uncultured and low-abundance microbes, the discovery of potential interactions among different microbial groups and the quantitative exploration of this complex ecosystem which has co-evolved with its host.

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2.1  Rumen microbial diversity 2.1.1  Rumen bacteria Rumen bacteria are the predominant microorganisms in the rumen, and account for more than 95% of the population with a high density of 1010 to 1012 bacterial cells/g of rumen content (measured through direct count) (McSweeney et al., 2005). They are highly variable in size, shape, organization and substrate utilization (Zhou et al., 2015). The rumen bacterial population can be classified into four main subpopulations: liquidassociated (Tajima et al., 2007), solid-associated (Brulc et al., 2009), epithelium-associated (Lukas et al., 2010) and eukaryote-associated. The last category of these populations has a symbiotic relationship with rumen protozoa and fungi (McSweeney et al., 2009). To date, numerous studies on analysing rumen microbial communities using nextgeneration sequencing have estimated that rumen microbiota contain up to approximately 7000 bacterial species. Of these, approximately 19 existing bacterial phyla have been identified, with phyla of Firmicutes, Bacteroidetes and Proteobacteria and genera of Prevotella, Bacteroides and Clostridium dominating in most of the cattle rumens (Brulc et al., 2009; Cai et al., 2013) and approximately 30% of microbiota remain unidentified (McSweeney and Mackie, 2012). The abundance of the bacterial groups differs depending on the ruminant species, the breed, whether the animals are dairy or beef cattle, environmental conditions and diet. The factors affecting the rumen microbial diversity are summarized in Section 3.

2.1.2  Rumen archaea Rumen archaea (methanogens) have been widely studied due to their importance in enteric methane production, which contributes to both greenhouse gas (GHG) emissions and feed energy loss (2–12%) for the animal (Hook et al., 2010). Generally, archaea have a population of 107 to 108 cells/g rumen contents, with Methanobrevibacter (>60%), Methanomicrobium (~15%) and Methanomassiliicoccales (a group of uncultured rumen archaea previously referred to as rumen cluster C, RCC) (~16%) as the predominant genera in the rumen archaeal community (St-Pierre and Wright, 2012; Borrel et al., 2014). As with ruminal bacteria, many factors can influence the structure of the rumen archaeal community. Many studies have focused on changes to the archaeal community under different feeding regimens (Zhou et al., 2010; McSweeney and Mackie, 2012).

2.1.3  Ciliated protozoa Ciliated protozoa are the second most common microbes (by mass) in both domesticated and wild ruminants (Williams and Coleman, 1992). Although their functions are not well defined, it is commonly thought that they play an important role in rumen fermentation, for example, by facilitating fibre digestion and participating in the microbial protein turnover. The most prevalent protozoans in the rumen can be classified under genus level, including Epidinium, Entodinium, Diplodinium and Holotrich ciliates (Williams and Coleman, 1992). As with other microbial groups, knowledge of protozoa has been significantly increased through the application of molecular techniques (Skillman et al., 2006). Many studies have shown that the amount and composition of ruminal protozoa are correlated with dietary changes (Leng et al., 2011; Tymensen et al., 2012). It is also known that certain bacteria

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and methanogens are symbiotic with protozoa. Protozoan-associated methanogens are estimated to be responsible for up to 37% of enteric methane (Tymensen et al., 2012). Although a difference in methane production has been observed between ciliateassociated and non-ciliate-associated methanogens (Belanche et al., 2014), it is not clear how such microbial interaction variation influence overall rumen function.

2.1.4  Anaerobic fungi Anaerobic rumen fungi have evolved with the ability to hydrolyse lignocellulose, and contain fibre digestive enzymes such as cellulases, xylanases, mannases, esterases, glucosidases and glucanases (Ishaq, 2015). Rumen fungi have been classified into six genera: monocentric Neocallimastix, Caecomyces, Piromyces, polycentric Anaeromyces, Orpinomyces and Cyllamyces (Ishaq, 2015). Generally, anaerobic rumen fungi account for up to 20% of the total microbial biomass (Rezaeian et al., 2004). So far, more than 18 species of anaerobic rumen fungi have been described through the use of molecular biological techniques such as the specific quantitative polymerase chain reaction (qPCR) technique and high-throughput sequencing technology (Denman et al., 2008). Population structure is highly correlated with dietary changes (Edwards et al., 2008). It has been proposed that fungi play a more significant role in rumen fermentation than bacteria (Lee et al., 2000), due to their ability to penetrate deeper into substrates which are not available to surface-acting bacteria. Comprehensive understanding of rumen fungi requires intensive research in taxonomy and genetic diversity.

2.1.5 Ruminal viruses (including Bacteriophages and Archaeaphages) Viruses, especially phages, are plentiful and diverse in the rumen. They were first identified in the 1960s, but very little research was carried out until the 1990s. Bacteriophages are abundant (107–109 particles per ml) in the rumen ecosystem, but their population structure and symbiotic relationships are poorly understood (McSweeney and Mackie, 2012). Several studies have pointed out the influence of rumen viruses on the structure and density of other microbial populations, due to cell lysis and possible lateral gene transfer (Hegarty and Klieve, 1999). They may play a beneficial role by balancing the bacterial populations, and may, through lateral gene transfer, add novel enzymes to the rumen ecosystem and host animals. However, they also have detrimental effects such as reducing feed efficiency and transferring toxin genes (Gilbert and Klieve, 2015). Recent metagenomic analysis of the bovine rumen virome identified 28 000 different viral genotypes belonging to several families (Siphoviridae, Myoviridae, Podoviridae, Unclassified, Herpesviridae, Phycodnaviridae, Mimiviridae, Poxviridae, Baculoviridae, Iridoviridae, Polydnaviridae, Adenoviridae, Bicaudaviridae) (Berg Miller et al., 2012). Moreover, studies have identified prophages as the predominant lytic phages, and have revealed their association with predominant bacterial phyla (Firmicutes, Bacteroidetes and Proteobacteria) (Swain et al., 1996). This cell lysis may also play a vital role in supplying microbial amino acids to the animal for protein synthesis.

2.2  Function of rumen microbiota Rumen microbes play a vital role in the nutritional, physiological and protective functions of the host. About 70% of the metabolic energy requirement of ruminants is fulfilled © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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through rumen fermentation and the associated breakdown of feed components into VFAs (Bergman, 1990). Community composition, the physiology of different microbial species, the interaction between different microbial groups and the interaction of microbiota with the host animal (Zhou et al., 2015) are extremely important in rumen function. It is a major advantage of ruminant agriculture that fibre can be digested through the degradation of plant cell walls by a complex community of fibrolytic microbes including rumen bacteria and fungi, thus converting poor-quality roughages into highly valued products. Starch and other soluble carbohydrates are degraded in the rumen by the combined enzymatic activities of bacteria, protozoa and fungi (McSweeney and Mackie, 2012). The rumen microbial fermentation produces short-chain VFAs, primarily acetate, propionate, butyrate and other by-products such as carbon dioxide, hydrogen, methane, ammonia and lactic acid. This process is also related to reducing equivalent disposal, which is a critical feature of fermentation (Russell and Rychlik, 2001). Acetate is the dominant VFA, and the rate of production depends on hydrogenase activity (Russell and Rychlik, 2001). Thus, rumen acetate production is highly correlated with enteric methane production. In contrast, when carbohydrate is metabolized to propionate, butyrate or lactate, dehydrogenase reactions are involved; therefore, feed energy loss as methane and heat is reduced. Fermentation product profiles are therefore dependent on feed quantity and quality, as well as on the rumen microbes which dictate to the animal’s performance. Moreover, the energy (ATP) availability is determined by the method of reducing equivalent disposal (Russell and Rychlik, 2001), where propionate shows high-energy efficiency over other VFAs through the process of gluconeogenesis. As such, a low acetate to propionate ratio is desirable, because it is related to better growth performance of the animal. Protein digestion and metabolism in the rumen occur when dietary protein and non-protein nitrogen are metabolized into ammonia by proteolytic bacteria through enzymatic protein hydrolysis, degradation of peptides and amino acid deamination (Cotta and Hespell, 1986). The ammonia can then be either used by cellulolytic bacteria for protein synthesis or absorbed by the host. Thus, the rate of rumen microbial protein synthesis is dependent on available energy, rather than on the availability of sources of nitrogen because of the synchronization of degradation between protein and carbohydrates in the rumen (Hackmann and Firkins, 2015). It has been shown that microbial protein production in the rumen is greater given highly fermentable carbohydrate sources, rather than low-quality feeds (Oba, 2011). VFA production profiles will also be altered (Hoover and Stokes, 1991). It is, therefore essential to balance highly degradable nitrogen content with carbohydrates. In addition, rumen microbes are also involved in lipid degradation, where dietary lipids (triglycerides, galactolipids and phospholipids) are rapidly hydrolyzed into glycerol, free fatty acids and galactose (McCann et al., 2014). However, most of these functions have been defined based on isolated cultures. It is not yet fully understood how dynamic changes in rumen microbiota affect rumen function at the carbohydrate, protein and lipid metabolism levels.

3  Factors influencing composition of rumen microbiota The rumen ecosystem is dynamic, and many factors have been identified to have an effect on rumen microbial diversity, density and functions. These include diet, breed, age of the © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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animal, physiological conditions and growth stages of the animals; season, geographical location, feed additives, feeding strategy and intensity; intake level and animal health as well as medical treatment (antibiotic usage) (Weimer et al., 2000; Romero-Perez et al., 2011; Hernandez-Sanabria et al., 2012; McCann et al., 2014). Any change in the rumen microbial ecosystem could be the result of one or multiple factors. The most studied factors are described below.

3.1 Effect of diet, feed intake and feeding regimes on rumen microbiota Diet plays a key role in shaping the rumen microbial community, and it is therefore the most extensively studied factor. The rumen microbial community and/or its by-products change in response to various dietary conditions, with the rumen microbial ecosystem adapting to have optimum population dynamics to utilize the available nutrients. Some ruminants are fed highly fermentable, grain-based diets in order to meet the energy requirement for high productivity. When there is a dietary transition from forage-based to grain-based diets, changes in the composition of the rumen microbiota are observed, with a reduction in fibre-utilizing microbes and a corresponding increase in those which utilize soluble carbohydrate (Penner et al., 2010; Henderson et al., 2015). Changes are also observed in other physical and chemical properties of the rumen, such as pH and VFA concentrations. A rapid change to a nutrient-dense, grain-based diet can result in the accumulation of VFA and other organic acids, thus causing a decrease in pH and further changes in the microbial community (Kleen et al., 2003; Plaizier et al., 2008). Feed intake levels (Crater et al., 2007) and frequencies of feeding (Pulido et al., 2009) also shape the rumen microbial community. In addition, a considerable amount of research has focused on methanogens and their activities under different dietary conditions (Kumar et al., 2009; Zhou et al., 2009, 2013), management (Buddle et al., 2011), and for animals in different physiological states and at different ages (Zhou et al., 2015).

3.2 Effect of age and physiological condition on rumen microbiota The structure and ecology of the rumen microbiota changes with the age of the host animal, with a particularly significant difference observed between youth and adulthood. Early studies based on culture methods could only describe the changes in rumen microbes with age, with a focus on initial rumen colonization in newborn lambs (Hobson and Fonty, 1997; Fonty et al., 2007; Béra-Maillet et al., 2009). Recently, several studies have been carried out to investigate microbial colonization and different factors affecting early microbial colonization (Malmuthuge et al., 2012, 2014, 2015). A detailed understanding of early rumen colonization could help us to understand how this unique organ develops (functions, morphology and colonization), which could provide the means to manipulate its functions to improve the rumen function and cattle production.

3.3  Effect of host genotype on rumen microbiome It is difficult to determine the effects of host genetics on rumen microorganisms due to the confounding effects of diet and rumen microbial population dynamics and lack of microbial data available from large populations. However, recent studies have focused © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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on the co-evolution of gut microbes and host animals using the microbes’ substrate preferences and their possible interaction with the host genotype (Ley et al., 2008). It has been reported that rate of feed intake, which is highly correlated with rumen fermentation and microbial population, varies significantly between individual animals within the same breed and when fed the same diet (Maekawa et al., 2002; Beauchemin and Penner, 2009; Penner et al., 2010). For example, longer fermentation and rumen retention time has been linked to higher methane production from animals of the same species, but Bos indicus cattle, who have faster rumen fermentation and shorter rumen retention time than Bos taurus cattle, were found to harbour a higher rumen methanogen population and produce more methane (Hennessy et al., 2000; Shi et al., 2014). Further, studies also identified host specificity in the symbiotic rumen microbial community (Penner et al., 2010; Weimer et al., 2010; King et al., 2011; Carberry et al., 2014; Roehe et al., 2016). Results from the above studies suggest that host factor should be taken into account when explaining the variation observed in rumen microbiota.

3.4 Effects of geography, season and host adaptations on rumen ecology Factors such as geography, climate, habitat pressure, behaviour and ecology influence the diversity and evolution of rumen microbes. Ruminants have therefore been classified into three broad groups: ‘concentrate selectors’, ‘intermediate feeders’ and ‘grass and roughage eaters’, based on their morphological variations, adaptations related to feeding behaviour and digestive physiology in relation to the geographic diversity of the ruminant’s ecological niche (Hofmann, 1989). Different feeding behaviours and forage selection resulted in differences in substrate availability to the host animals, especially the plant cell content that has been proven to impact the anatomical features of different ruminants (Karasov et al., 2011; Carberry et al., 2012). Changes have been observed in rumen fermentation, retention time, pH, microenvironment and the symbiotic gut microbiota in different animals, and such variation then further influences host phenotype, including growth and production (Hofmann, 1989; Jami and Mizrahi, 2012). Some studies have shown that diet and geographic location have a greater impact on the rumen microbiota than do the genetics of the host animal (Carberry et al., 2012; Rodríguez et al., 2015). Moreover, several studies suggest that rumen populations change with seasonal variations in climate, photoperiod and changes of forage availability for grazing cattle (Barboza et al., 2006; Fernando et al., 2010). Beef cattle with re-ranking residue feed intake may exhibit changes in rumen fermentation, leading to an alteration in the rumen microbiome (Carberry et al., 2012, 2014). Given poor-quality feeds, a reduced rate of rumen feed passage within the digestive tract, coupled with increased nitrogen recycling, was observed, rather than an increase in rumen bacteria (Fields, 2004; Sarnklong et al., 2010). Such factors must also be considered when manipulating rumen microbiota.

4 Current trends and innovations in studying the rumen microbiome: ‘omics’ approaches Culture-based methods have many limitations; using such methods, only a very small fraction (1%) of rumen microbes (Zhou et al., 2015) were identified over the course of © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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decades of research. Since the majority of rumen microbes were not isolated and identified using these traditional methods, the descriptions of rumen community composition were not complete. With the application of molecular biology techniques, the diversity of rumen bacteria and archaea could be assessed by analysing microbial gene sequences against available databases (Whitford et al., 1998; Kim et al., 2011; Cole et al., 2013). Primary molecular studies were mainly based on the 16S rRNA gene, and this gave promising results because it is a conserved gene expressed among all prokaryotes with similar sequence length (Zoetendal et al., 2008) and some polymorphic regions. Fingerprinting and clone library sequencing help to increase the understanding of rumen bacterial diversity; however, these methodologies cannot detect the microbes with relatively low abundance (Zhou et al., 2015). With the development of high-throughput, next-generation sequencing techniques, studies of the rumen microbial community have proceeded by sequencing various polymorphic fragments of 16S rRNA genes, and a more diverse microbiota has been revealed, including phylotypes with low abundance in the rumen. As well as identifying the composition of the rumen microbiota, current research studies aim to discover microbial activities and methods to redirect the rumen microbiome for better functions. The latter will be the topic of Section 6, while this section focus on ‘omics’ approaches to answer two key questions: What microbes are present and what are they doing in the rumen? In the old days, studies of the rumen microbiology focused on isolating individual species from the rumen liquid and content samples, and then studying their biochemical features based on the cultures. However, since many rumen microbial species (namely viable but unculturable (VBNC) species) require extremely strict cultivation conditions and cannot be isolated, other methods are required to study these species and understand their impact on host performance. Handelsman (2004) pointed out that applying metagenomics to study the microbiome can help us to identify the composition of the entire microbial community and function, reveal the competition and communications within the microbiome and potentially understand the symbiotic relationships between microbes and hosts. Brulc et al. (2009) studied the metagenomes of the rumen content collected from three beef steers and revealed fundamental variations in the glycoside hydrolase (GH) content of the steers fed on forages and legumes compared to that in the hindgut of termites fed on wood. They concluded that such significant variation in GH between rumen and termite hindgut was driven by different diets. However, a remarkable individual variation of GH composition was also found among the three steers, emphasizing that even under identical raising conditions each animal should still be considered independently (Brulc et al., 2009). Hess et al. (2011) also applied metagenomic analysis to study the rumen microbiome of dairy cows. They identified 27 755 putative carbohydrate-active genes, and 90 candidate proteins of which 57% were active against cellulosic compounds of the feed. In addition, they assembled 15 unculturable microbial genomes to add to the rumen microbial reference database. Microbial plasmids also encode essential functional genes. Metagenome analysis revealed that rumen microbial plasmidomes in cows are enriched in functions including ‘plasmid backbone function’ and ‘biosynthesis function’ (Kav et al., 2012), which may also contribute to functions of rumen microbiome. In contrast to the studies which focus on beef cattle and dairy cows under conventional raising systems, some studies have focused on ruminants fed with low-quality diets and given harsh survival conditions. Such studies offer valuable knowledge for enhancing fibre digestion in farm ruminants. Pope et al. (2012) studied the rumen microbial © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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metagenomes of high-arctic reindeer, which survive under austere nutritional conditions. This revealed numerous novel microbial polysaccharide utilization loci-like systems in addition to cellulolytic enzymes commonly found in cattle and buffalo rumen. Their findings have pointed out novel mechanisms for rumen cellulose degradation, which could be important targets for future study to improve utilization of poor-quality forages in all ruminants. Dai et al. (2012) studied the rumen metagenome of yak fed on a wheat stalk diet. They identified genes encoding SusC/SusD-type outer membrane proteins, and found that GH genes such as GH5, GH9 and GH10 were predominant within the examined metagenome. They proposed that in yak rumen, the SusC/SusDinvolving mechanisms may be the main lignocellulose degradation system, and that an endoglucanase of a novel GH5 subfamily also plays an important role in contributing to the lignocellulose degradation. Patel et al. (2014) examined the rumen metagenome of buffaloes fed on different proportions of green or dry roughage, and found that the buffalo rumen microbiome harboured a greater number of debranching enzymes and oligosaccharide-degrading enzymes compared to cow, termite and chicken symbiotic microbiomes. This trait of the buffalo rumen metagenome may be one of the key factors allowing them to survive on coarse feed. Metagenomic analysis helps to discover the functional potentials within the rumen microbiome, but it cannot reveal the actual activity. Thus, metatranscriptomics, which study the active transcripts of microbial genes, should also be employed. Findley et al. (2011) isolated total RNA from cow rumen fluid and examined the transcripts of protozoan GHs. They identified four novel genes among which two (type 1-7.1 and type 2-8.6) were characterized in downstream biochemical assays. Metatranscriptomic analyses performed in cow rumen (Dai et al., 2012) have proved that the GHs produced by Ruminococcus, Fibrobacter and Prevotella were the predominant degraders of plant cell wall polysaccharides (PCWP), with GH48 cellobiohydrolases and cellulosome-like structures playing significant roles in efficient PCWP degradation. In order to gain a complete understanding of the rumen microbiome, it is also important to identify the microbial metabolites which can be utilized by the host or which can influence the rumen environment and host health. Butyrivibrio proteoclasticus B316T, a polysaccharide-degrading and butyrate-producing bacteria prevalent in the rumen, was reported to produce intracellular debranching enzymes (Dunne et al., 2015). This suggests a plausible model according to which this species is capable of conducting extracellular digestion of hemicellulose to oligosaccharides, followed by transporting the oligosaccharides to the cytoplasm for further digestion by intracellular enzymes (Dunne et al., 2015). With these ‘omics’-based approaches, it is possible to study the composition, activities and functions of the rumen microbiome systematically.

5 Current trends and innovations in studying the rumen microbiota: linkage with host phenotypes 5.1  Feed efficiency With our developing knowledge of rumen microbiota, it is feasible to explore the impacts of the rumen microbiome on host performance by associating microbial measurements © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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with host phenotypes. One such application is to define the roles of rumen microbiota in affecting host feed efficiency. Hernandez-Sanabria et al. (2012) have analysed the rumen bacteria in beef cattle with varied residual feed intake (RFI) under growing and finishing diets. They found that the abundance of Succinivibrio sp. was associated with host dry matter intake and average daily gain in low-RFI (efficient) animals, Robinsoniella sp. abundance was associated with high-RFI (inefficient) animals, whereas the abundance of Eubacterium sp. differed between RFI groups when animals were fed with a feedlot finishing diet. With deeper coverage of sequences, Myer et al. (2015) reported that although Bacteroidetes and Firmicutes were the dominant phyla regardless of host feed efficiency differences, proportions of Succiniclasticum, Lactobacillus, Ruminococcus and Prevotella differed among animal groups with varied feed intake and body weight gain. Jami et al. (2014) have identified a tentative correlation between the relative abundance of bacteria of the order RF39 and host RFI (R = 0.51) in dairy cows. In addition to these findings on bacteria, both Zhou et al. (2009, 2010) and Carberry et al. (2014) reported that although the total methanogen population was similar, changes in the abundance of particular archaeal genotypes may have contributed to the variation in host methane production, and so impacted host RFI.

5.2  Methane emission Mitigating enteric methane emissions from ruminants has attracted increasing attention, since this would allow a reduction in GHG emissions in the agricultural sector, as well as minimizing dietary energy loss in the host animals. Zhou et al. (2011) studied the rumen methanogens of Holstein cows and found that host methane emission was positively correlated with a phylotype close to Methanobrevibacter gottschalkii, rather than being correlated with the total methanogen population in the rumen. Wallace et al. (2015) measured the metagenome of beef cattle selected for extremely high and low methane emissions, and observed 2774 proteins correlated with methane emissions. In addition, they also claim that a lower abundance of Succinivibrionaceae may be linked to a decrease in acetate production, and thus further contribute to the lowered methane. This will be discussed further in Section 6.

5.3  Ruminal acidosis A natural rumen microbiota is a well-adapted, stable ecosystem. With nutritional management, the stability of the microbial ecosystem may be disturbed, resulting in a metabolic disorder in the host animal. This is a particular risk when animals are fed with nutrient-dense diets, because these may unbalance the ecosystem by providing an excessive supply of substrate to some microbes. On the other hand, a deficient amount of some nutrients may also lead to an unstable system. Ruminal acidosis is a digestive disorder developed when animals have a rapidly fermentable diet. It is particularly common in the dairy industry (Oetzel, 2007). Acidosis is characterized by depressed rumen pH for a prolonged period (Plaiziera et al., 2008), due to the accumulation of fermentation end products, VFAs and lactic acid. Changes in rumen pH have an adverse effect on rumen flora and fermentation processes. Acidosis can be divided into two categories: clinical and sub-clinical (Beauchemin and Penner, 2009). It may result in decreased feed intake, depressed milk fat (Kleen et al., 2003), laminitis (Nocek, 1997) and liver abscesses (Nagaraja and Titgemeyer, 2007). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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The depressed pH and the resulting acidosis are caused by diet (Steele et al., 2011) but their severity will depend on several factors such as the diversity and abundance of rumen microbiota, the structural adaptation of rumen epithelium (Steele et al., 2011), the rate of absorption of VFA and buffering (Steele et al., 2012). Recent studies have shown that ruminal bacterial communities in beef steers can be divided into those which are subacute ruminal acidosis (SARA) resistant and those which are susceptible (Chen et al., 2012). Bacterial community changes were also associated with SARA severity (Khafipour et al., 2009) in dairy cows, suggesting that rumen microbiota play a role in rumen metabolic dysfunction. Future studies are needed to verify whether such changes cause SARA or ruminal acidosis.

5.4  Quality and safety of animal products Understanding rumen microbial lipid metabolism is also important, since the rumen microbiota ferments ingesta into various short-chain fatty acids which are then absorbed by the host to create animal products. Jami et al. (2014) have shown a strong correlation between milk fat yield and the Firmicutes:Bacteroidetes ratio, indicating that an increased Bacteroidetes population in the rumen may be associated with higher adiposity of the host. In addition, four genera (Atopobium, Adlercreutzia and two unknown genera belonging to the order Coriobacteriales) were found to be positively correlated with milk lactose content (Jami et al., 2014), implicating their crucial roles in supplying the host with substrates for lactose synthesis. The fatty acid profiles of subcutaneous adipose tissue were also shown to be associated with rumen bacterial populations and fermentation (Petri et al., 2014): a low level of vaccenic acid in subcutaneous fat was accompanied by a smaller population of Anerophaga, Fibrobacter, Guggenheimella, Paludibacter and Pseudozobellia in the rumen, while a high abundance of Clostridium was accompanied by low levels of n-3 polyunsaturated fatty acids and conjugated linolenic acids in subcutaneous fat tissue, implying that Clostridium bacteria play a role in biohydrogenation. Supplementing steer diets with flax oil resulted in higher proportion of Butyrivibrio, Howardella, Oribacterium, Pseudobutyrivibrio and Roseburia, while with echium oil Succinivibrio and Roseburia were increased (Huws et al., 2015). The substantial degree of rumen biohydrogenation seen with either flax oil or echium oil supplements, together with the resulting changes in rumen microbiome, have been proposed as a method of triggering an alteration in the fatty acid composition of ruminant products. The above findings, together with numerous results in other studies, have illustrated the importance of the rumen microbiome and microbial metabolism in altering host phenotypes. Ruminants host both beneficial and pathogenic microbes in their gastrointestinal systems. Human health can be affected positively by the supply of nutrients in meat and dairy products, and negatively by the occurrence of zoonotic disease through food or environmental contamination. Until recently most of the ruminant gastrointestinal tract microbes were not considered to be zoonotic, but pathogens such as Salmonella spp., Escherichia coli strains such as E. coli O157:H7, Listeria monocytogenes and Camphylobacter spp. have now been identified, increasing concerns about the prevalence of pathogens in the gut (Pell, 1997; Oliver et al., 2005; Gannon et al., 2012). A recent study of E. coli O157:H7 proteome in the rumen showed that when this pathogen colonized the rumen, it expressed specialized proteins which enabled it to adapt to the rumen environment, and then to colonize the lower gastrointestinal tract (Kudva et al., 2014). © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Moreover, with modern intensive farming there is increasing concern about transmission of antibiotic resistance and chemical residues from livestock to human systems. In intensive animal agriculture, antibiotics are often used to control/prevent disease and to promote growth (McEwan and Fedorka-Cray, 2002). Consumers are giving increasing attention to the potential for the transmission of antibiotic-resistant gut microbiota and associated genetic elements from ruminants to humans, and thus raising questions about the safety of animal products.

6  Altering rumen function by manipulating microbiota Identifying the variation in rumen microbiota in hosts under different conditions, and recognizing the association between rumen microbiome and host phenotype, raises a key question: Can we improve rumen function by manipulating rumen microbiota? Several studies have explored altering rumen function by changing microbiota, with the aim of increasing feed efficiency and reducing methane emissions. Dietary modulation is the most commonly used method to redirect the rumen microbiota for short experimental periods. Animals fed diets of different forage:concentrate ratios harboured distinctive rumen microbial communities and had different fermentation parameters (e.g. SadetBourgereau et al., 2010; Hernandez-Sanabria et al., 2012; Petri et al., 2014). Compositional changes in the rumen microbiome have also been widely reported after supplying high grain diets, with changes in VFA production and host functions (Hernandez-Sanabria et al., 2012; Petri et al., 2014). Increased dietary fat such as fatty acids (e.g. Dohme et al., 2001) and essential oils (e.g. Mclntosh et al., 2003) have also been shown to reduce methane emissions remarkably. However, extreme dietary alterations may lead to increased cost, changes in milk and meat quality, and various metabolic disorders such as acidosis and ketosis. The use of different feed additives and rumen modifiers to increase feed efficiency, including direct fed microbes (Lettat et al., 2012; Qadis et al., 2014) and ionophores (Dennis and Nagaraja, 1981), have been shown to result in noticeable reductions in methane emissions. In particular, ionophores (monensin, lasalocid, laidlomycin, salinomycin and narasin) are selective anti-microbial compounds commonly used as feed additives in ruminants to improve feed efficiency (Callaway et al., 2003), resulting in increased carbon and nitrogen retention in the animal body. A vaccine has also been used for selective elimination of methanogens responsible for methane emissions, with varied success rates (Wright et al., 2004; McAllister and Newbold, 2008; Wedlock et al., 2013). The impacts on rumen fermentation parameters and the persistence of the effects in reducing methane differed among studies. In contrast, the recently developed 3-nitrooxypropanol (3-NOP) (Duval and Kindermann, 2012) has been shown to consistently alter the rumen microbiota and reduce methane production regardless of experimental method (in vitro vs in vivo), host variation (dairy cows/beef cattle/sheep) and experiment length (short-term vs long-term) (Martínez-Fernandez et al., 2014; Reynolds et al., 2014; Haisen et al., 2014, 2015; Romero-Perez et al., 2014, 2015; Hristov et al., 2015). The effectiveness of 3-NOP in these studies guarantees that there will be further studies to identify whether it has toxic effects on the animals, and how it influences individual microbial species within the rumen. Rumen content exchange is not a novel concept in nutritional practices, but the impact of introducing a donor microbiota into a recipient’s rumen remains largely unknown.

© Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Weimer et al. (2010) exchanged the rumen contents of two pairs of dairy cows, with differing rumen pH/total VFA concentration/bacterial composition within this pair. In the case of one of these pairs, the animals’ microbiota re-established to near their original profile. In the second pair, by the end of the experiment the rumen of each animal also showed higher similarity to its own pre-exchange status than to that of the donor, although a distinction still existed. These results suggest that allowing an adequate adaptation period (14 to 61 days in this study), the rumen microbiota had gradually adapted to give each cow similar rumen fermentation parameters to those each had exhibited at the beginning. In a later study by Zhou et al. (unpublished data), which also exchanged rumen content between animals with different feed efficiency, it was found that certain phylotypes have higher potential for manipulation than others. It has been speculated that the functional features of the altered phylotypes have an impact on host feed efficiency. Currently, there is an urgent need to develop effective content removal methods and to define standards indicating host microbiome/rumen function changes. The early life of a ruminant, before the rumen microbiome is properly established, provides a unique opportunity for manipulation, as it allows us to avoid dealing with the quick adaptation of the adult’s rumen microbiota to dietary treatment. Fonty et al. (2007) introduced acetogens into gnotobiotic lambs, and observed that the major rumen hydrogenotrophic process shifted towards acetogenesis, and this change was sustained for 12 months. These methanogen-free lambs grew well, and their rumen fermentation measurements were not remarkably dissimilar from those of conventional lambs, suggesting that such a practice may be one of the options for mitigating enteric methane. Abecia et al. (2013) applied bromochloromethane to young kid goats, and successfully modified rumen methanogen colonization and reduced enteric methane for 3 months. Initial colonization of the rumen microbiota occurs straight after birth (Rey et al., 2013; Guzman et al., 2015), suggesting that the timeframe allowing microbial ‘programming’ during early life is very limited. However, it is reported that rumen function development occurs after microbial colonization, and anatomic development comes later still (Jiao et al., 2015). Promising and long-lasting schemes to ‘reprogramme’ the rumen microbiota in pre-weaned ruminants (e.g. Abercia et al., 2014a,b; Zhong et al., 2014), and practices developed for gnotobiotic lambs (Fonty et al., 2007) or naturally born lambs raised under sterile isolators (Gagen et al., 2012) warrant further investigation to determine the optimal timeframe for microbial colonization intervention in young ruminants. On the basis of the above findings, the alterations in microbial composition and fermentation differed from host to host, and this should be borne in mind in any programme to manipulate the rumen microbiota. Future studies identifying the correlation between host genetics and individual responses to transplantation are needed, in order to develop novel techniques in this area for use in the agricultural industry.

7  Knowledge gaps and future directions As described above, rumen microbiota has been widely studied in recent years, using recently developed high-throughput sequencing technology. However, the roles and importance of particular microbial phylotypes in specific functions in the rumen are not yet well characterized. In addition to expanding our limited understanding of microbial physiological changes and activities, we must address several unanswered questions in

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order to develop the ability to improve production and health through enhancing rumen function.

7.1  Can we breed cattle with desirable rumen microbiota? The importance of host-related factors in affecting the symbiotic microbiota has been noted. However, the role of the host’s genetic make-up, and the degree to which it regulates rumen microbiota, are unknown. In ruminants, microbial ecology was more similar within the same host species than between different species (Jeyanathan et al., 2011). Dairy cows of the same breed host are more closely related in terms of microbial diversity than those of different breeds (King et al., 2011). Evidence even shows that different individuals within the same breed display varied ruminal microbial ecology (St-Pierre and Wright, 2012). In addition, the sire breed of steers has an impact on the rumen microbial phylotypes of their offspring (Hernandez-Sanabria et al., 2013) and each animal responds to dietary changes differently (Zhou et al., 2013). As stated in this chapter, rumen microbiota could be associated with cattle feed efficiency, and this is breed dependent (Guan et al., 2008; Hernandez-Sanabria et al., 2013). Roehe et al. (2016) have provided evidence that we may be able to develop desirable genetic selection strategies for rumen function through their findings, which identify microbial genes and host–microbial cross-talk genes associated with feed conversion efficiency. There has been a debate about whether rumen microbiota is heritable or not. Recent findings from studies which surveyed rumen microbiota from global samples suggest that diet has a larger influence on microbial composition than the host effect (Henderson et al., 2015) and this seems to support the theory that environmental factors may be the main driver of microbiota composition. However, recent studies on human microbiota have started to provide evidence that host genetics can indeed play a role in determining gut microbiota. For example, by profiling the interactions between human genetic variation and microbial composition using a genome-wide association study, Blekhman et al. (2015) have highlighted the role of host genetic variation in shaping the composition of the human microbiota. Another recent study further revealed that such a host effect could be microbial taxa-dependent, and that some taxa are both inheritable and associated with human obesity (Goodrich et al., 2014). This suggests that a host effect could have been masked when the whole rumen microbiota was examined by Henderson et al. (2015). Attempts to dissect the rumen microbiota and its interaction with host genetics through collaborative efforts to collect genome-wide genotyping and microbiota data are key steps for future research. Such research should help us to understand the complex interaction between animal genetics and the rumen microbiota in the context of animal production and health.

7.2  Causes or consequences A large amount of sequencing data has been generated through attempts to explore the rumen microbiota and microbiome at both structural and functional levels, as well as to associate the presence or absence of particular microbial phylotypes and/or changes in their abundance with phenotypic trait variations. The most intriguing findings are the potential links between rumen microbiota and cattle feed efficiency, methane emission and ruminal acidosis, as summarized in this chapter. However, changes in a rumen microbiota (microbiome) and their association with host phenotypes being revealed are © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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primarily limited at ‘gene level’ by using the commonly accepted ‘statistical’ analyses. The biological significance of the observed changes remains largely unknown, since whether the alteration of microbiota causes host functional changes or whether it is the result of host physiological changes cannot be clearly defined at this stage, based on current research models and tools. Recent research into the human microbiome has also faced the same challenges in dissecting the causes and consequences in host–microbial interactions. Gnotobiotic germ-free animal (murine) models have been widely used to determine the causal effect of gut microbes on host inflammatory responses, metabolic dysfunctions and diseases in humans (Nguyen et al., 2015). To identify the causal effects of the rumen microbiota, it will be necessary to develop ‘germ-free’ ruminants which could be used to validate and verify the microbes we have identified as potentially being associated with feed efficiency, ruminal acidosis and so on. However, with the diverse genetic background and different physiological gut environments in humans, the detected ‘causal’ effect in germ-free mice cannot reflect and explain the large individual variations in human gut microbiomes and their interactions with their hosts. This could be also the case for potential ‘germ-free’ models in ruminant studies. As genes only provide information on potential functions at the genetic level, studies on the microbial transcriptome must also be pursued. Metabolite profiles will be required to further understand how microbiome changes affect host physiology and health. It has been proposed that a multidisciplinary approach is necessary, and must include profiling not only of the gut microbiota but also of the host, so as to elucidate the role of the gut microbiome in human health and disease (Integrative HMP (iHMP) Research Network Consortium, 2014). We can handle and process data from large cohorts to determine how diet composition, management, host genetics and animal health status affect or are affected by the rumen microbiota, and then apply this information to improve animal production and health. Indeed, we need further technological development, new data analytical methods and collaborative research efforts.

8 Conclusions Recently developed, advanced sequencing-based technologies have led to the detailed identification of rumen microbiota/microbiome at both taxonomic and functional levels. The microbial diversity and vast array of functional properties of the rumen microbiome provides new insights into the role of the rumen in ruminant production and health. Collaborative efforts in studying large populations using integrated approaches including animal genetics, nutrition and physiology, rumen microbiology and functional genomics will be needed to fill the current knowledge gaps and pave the way for future applications in improving production efficiency and health through manipulation of rumen microbiota.

9  Where to look for further information Listed below are some additional (but not exhaustive) resources for further exploration by the reader. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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9.1  Related books Rumen Microbiology. Dehority, B. A. (ed.), 2003. Nottingham University Press, ISBN:: 1897676999. Rumen Microbiology: From Evolution to Revolution. Puniya, A. K., Singh, R., Kamra, D. N. (eds), 2015. Springer, ISBN: 978-81-322-2400-6. Archaea: Molecular and Cellular Biology. Cavicchioli, R. (ed.), 2007. American Society for Microbiology, ISBN: 9781555813918. The Rumen Protozoa. Williams, A. G., Coleman, G. S. (eds), 1992. Springer, ISBN: 978-1-4612-7664-7. The Rumen Microbial Ecosystem. Hobson, P. N., Stewart, C. S. (eds), 1997. Springer, ISBN: 978-94-010-7149-9.

9.2  Related research networks RuminOmics: http://www.ruminomics.eu/ RMG Network: http://www.rmgnetwork.org/index.html

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The rumen microbiota and its role in dairy cow production and health177 McSweeney, C. S., Blackall, L. L., Collins, E., Conlan, L. L., Webb, R. I., Denman, S. E. and Krause, D. O. (2005) Enrichment, isolation and characterisation of ruminal bacteria that degrade non-protein amino acids from the tropical legume Acacia angustissima. Animal Feed Science and Technology, 121(1–2), 191–204. McSweeney, C., Kang, S., Gagen, E., Davis, C., Morrison, M. and Denman, S. (2009). Recent developments in nucleic acid based techniques for use in rumen manipulation. Revista Brasileira De Zootecnia, 38(SPE), 341–51. McSweeney, C. and Mackie, R. (2012). Commission on Genetic Resources for Food and Agriculture. Micro-organisms and ruminant digestion: State of knowledge, trends and future prospects. Background Study Paper (FAO), 61, 1–62. Myer, P. R., Smith, T. P., Wells, J. E., Kuehn, L. A. and Freetly, H. C. (2015). Rumen microbiome from steers differing in feed efficiency. PLoS ONE, 10(6), e0129174. Nagaraja, T. G. and Titgemeyer, E. C. (2007). Ruminal acidosis in beef cattle: the current microbiological and nutritional outlook 1, 2. Journal of Dairy Science, 90, E17–E38. Nguyen, T. L. A., Vieira-Silva, S., Liston, A. and Raes, J. (2015). How informative is the mouse for human gut microbiota research? Disease Models and Mechanisms, 8(1), pp.1–16. Nocek, J. E. (1997). Bovine acidosis: implications on laminitis. Journal of Dairy Science, 80(5), 1005–28. Oba, M. (2011). Review: Effects of feeding sugars on productivity of lactating dairy cows. Canadian Journal of Animal Science, 91(1), 37–46. Oetzel, G. R. (2007). Subacute ruminal acidosis in dairy herds: physiology, pathophysiology, milk fat responses, and nutritional management. In 40th Annual Conference, American Association of Bovine Practitioners, 17, 89–119. Oliver, S. P., Jayarao, B. M., and Almeida, R. A. (2005). Foodborne pathogens, mastitis, milk quality, and dairy food safety. In NMC Annual Meeting Proceedings, pp. 3–27. Patel, D. D., Patel, A. K., Parmar, N. R., Shah, T. M., Patel, J. B., Pandya, P. R. and Joshi, C. G. (2014). Microbial and Carbohydrate Active Enzyme profile of buffalo rumen metagenome and their alteration in response to variation in the diet. Gene, 545(1), 88–94. Pell, A. N. (1997). Manure and microbes: public and animal health problem?. Journal of Dairy Science, 80(10), 2673–81. Penner, G. B., Oba, M., Gäbel, G. and Aschenbach, J. R. (2010). A single mild episode of subacute ruminal acidosis does not affect ruminal barrier function in the short term. Journal of Dairy Science, 93(10), 4838–45. Petri, R. M., Mapiye, C., Dugan, M. E. and McAllister, T. A. (2014). Subcutaneous adipose fatty acid profiles and related rumen bacterial populations of steers fed red clover or grass hay diets containing flax or sunflower-seed. PLoS ONE, 9(8), e104167. Plaizier, J. C., Krause, D. O., Gozho, G. N. and McBride, B. W. (2008). Subacute ruminal acidosis in dairy cows: The physiological causes, incidence and consequences. The Veterinary Journal, 176(1), 21–31. Pope, P. B., Mackenzie, A. K., Gregor, I., Smith, W., Sundset, M. A., McHardy, A. C., Morrison, M. and Eijsink, V. G. (2012). Metagenomics of the Svalbard reindeer rumen microbiome reveals abundance of polysaccharide utilization loci. PLoS ONE, 7(6), e38571. Pulido, R. G., Muñoz, R., Lemarie, P., Wittwer, F., Orellana, P. and Waghorn, G. C. (2009). Impact of increasing grain feeding frequency on production of dairy cows grazing pasture. Livestock Science, 125(2–3), 109–14. Qadis, A. Q., Satoru, G. O. Y. A., Ikuta, K., Yatsu, M., Kimura, A., Nakanishi, S. and Shigeru, S. A. T. O. (2014). Effects of a bacteria-based probiotic on ruminal pH, volatile fatty acids and bacterial flora of Holstein calves. The Journal of Veterinary Medical Science, 76(6), 877. Rey, M., Enjalbert, F., Combes, S., Cauquil, L., Bouchez, O. and Monteils, V. (2014). Establishment of ruminal bacterial community in dairy calves from birth to weaning is sequential. Journal of Applied Microbiology, 116(2), 245–57. Reynolds, C. K., Humphries, D. J., Kirton, P., Kindermann, M., Duval, S. and Steinberg, W. (2014). Effects of 3-nitrooxypropanol on methane emission, digestion, and energy and nitrogen balance of lactating dairy cows. Journal of Dairy Science, 97(6), 3777–89. © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Chapter 8 Biochemical and physiological determinants of feed efficiency in dairy cattle John McNamara, Washington State University, USA 1 Introduction

2 The physiological and biochemical makeup of a dairy animal



3 Development of the research field: a brief overview



4 A case study on the biochemical determinants of feed efficiency



5 Mechanisms and effects of simple genetic variation



6 Summary and conclusions



7 Future trends in research



8 Where to look for further information

9 References

1 Introduction Dairy cows provide high-quality protein and other nutrients for humans. We must select and manage cows with the goal of reaching the highest possible efficiency for any given environment. We have increased efficiency tremendously over the years, yet the variation in productive and reproductive efficiency among animals is still quite large. In part this is because of a lack of (1) full integration of genetic, nutritional and reproductive biology into management decisions and (2) more complex integrated experiments which help define the multivariate nature of animal efficiency. However, integration across these disciplines is increasing as the biological research findings show more specific control points at which genetics, nutrition and reproduction interact. The energetic, physiological or metabolic efficiency of an animal is a multivariable effect of the dietary ingredients and physical form of the diet available; the bacterial population of the digestive tract; and the interactions of hormones, receptors, organs, and cell differentiation and metabolism patterns. This is a system, with both closed and open elements. An existing animal has a set genetic programme that can be met in part by an ideal amount and balance of nutrients. We cannot ‘improve the efficiency’ of a single animal by changing its genetics, but we can select for more efficient traits in populations over time. We cannot improve the maximal genetically defined efficiency of a single animal by dietary manipulation or housing and climate conditions; however, we can only hope to ensure the most optimal development of its genetic programme. http://dx.doi.org/10.19103/AS.2016.0006.09 © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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For the majority of this chapter we are going to assume for practical reasons that the housing, other environment and dietary form, and chemical composition are ideal and appropriate for the lactating dairy cattle. Clearly, this is not always the case and simple improvement of environment and feeding and nutritional management must continue to change in order to improve overall efficiency of dairy production. But to focus on the ‘biochemical and physiological determinants of feed efficiency’, we will assume that the genetic programme of the animal is being provided with the optimal environment. Also, the complex world of feed preparation, composition, evaluation, ration balancing and feeding management, and digestive elements is covered in depth in other chapters in the book. Another underlying theme of this chapter is that future significant improvement in feed efficiency of dairy cattle will come from continual genetic selection for key productive traits, including explicitly both dilution of maintenance by increasing production per cow (where the environment allows such an increase) and improvement of efficiency of feed utilization as a per cent by optimizing the proportions of feed used for maintenance and productive functions. It is stated explicitly here that these two frameworks are of course related and not antithetical, but that simple increased production per cow will not be obtainable in large parts of the world, and a different approach to improving the efficiency of use of what is available must be taken. However, the underlying biochemical and physiological determinants are the same, just of different expression. The major processes such as nutrient flux within and among organs and the hormonal, neural and biochemical regulation thereof in lactation are for the most part completely established and have been covered in many reviews and books (Baldwin, 1995; Bauman and Currie, 1980; Collier et al., 1984; Drackley, 1999). Therefore, we will provide a brief description of the physiology and biochemistry of the cow and then move on to research that has helped and continues to help define key determinants and patterns of efficiency. We will not address the basis or the ongoing work on residual feed efficiency (RFE) because, although it has research and practical utility, it is beyond the scope of this chapter and in and of itself does not lead to direct descriptions of the physiological and biochemical determinants of the efficiency of an animal or population of animals. In time, the findings from genetic characteristics of variation in RFE will be interpreted with the knowledge of which developmental or physiological process is affected.

2 The physiological and biochemical makeup of a dairy animal An existing dairy heifer that is pregnant and approaching her first calving (and for this description assumed to have been grown under the ideal conditions) is made up of a genetically determined constitution of muscle, bone, skin, brain and nervous tissue, circulatory and respiratory system, digestive organs ((oesophagus, including rumen, reticulum and omasum); gastric stomach (abomasum); small and large intestines) and liver, spleen, kidney, adrenal glands, pancreas and all other endocrine organs. The organs are connected directly by the circulatory system. This means that absorbed nutrients and metabolites are available for uptake by all organs in relation to their needs. It also means that hormones can be delivered to the appropriate receptors by the neural system so that all functions can be coordinated through the brain. The environmental driver of the © Burleigh Dodds Science Publishing Limited, 2017. All rights reserved.

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Biochemical and physiological determinants of feed efficiency in dairy cattle

uptake and exchange of nutrients and metabolites between organs is the amount and balance of nutrients available (absorbed from the intestines). The programmed uptake and use of nutrients by various organs (generally referred to as the ‘partitioning of nutrients’ (Hammond, 1940; Bauman and Elliott, 1983) is strongly regulated by the dominant physiological and/or environmental state of the animal through nervous signalling and several hormones, including alteration of the response of the organs to hormones and nutrients depending on the physiological state. A very generalized scheme is shown in Fig. 2. The reader is asked to note the fully integrated nature of the system. Regardless of the organ size or genetically programmed amount of somatotrophin or glucose transporters or any other control molecule, the system is completely integrated. A change in one part (say, the supply of glucose) has immediate and measurable effects on all the other parts from carbon and nitrogen pathway flux to endocrine control. The determinants of the efficiency of nutrient use within and among organs and the summative efficiency of the animal are thus an aggregate result of the genetic determinants of organ size and biochemical makeup (hormone receptor and enzyme content, for example) and the endocrine and neurocrine makeup of each individual animal. The regulation of nutrient flux within each cell type (organ) follows the same generic pattern as in Fig. 1, such that there is a makeup of chemical receptors, transporters, second messenger proteins, intracellular control proteins, DNA, mRNA, rRNA and tRNA, and enzymes which will have different specific expression and kinetic parameters in each organ during each physiological state. All or almost all of these constituents can be measured or activity estimated in one way or another. In order to describe specific control of animal efficiency research, one must really be focused on the underlying biology such as the genomic makeup, transcriptional regulation, enzyme pathways, and endocrine and thermodynamic control of the animal resulting in measureable whole animal processes. It needs to be noted that not all of these processes can or will become measurable traditional quantitative traits, but all of them contribute to the specific efficiency of a given animal. DNA transcription site*

Receptor*

Nucleotides

cAMP

Hormone* or Nutrient Initial substrate(s)

mRNA

Substrate

*K1 enzyme

>>> Pathway >>>

Vm, Ks*

Amino acids

*K2

product End Product

41%

>43%

Risk for elevated FPR is slightly higher then average

The percentage of first lactation cows "infected" at first test date is about industry average, but the multiparous cows are better than average.

13%

12%

7%

deaths