The breeding structure of the purebred Aberdeen -Angus cattle population in the United States from 1900–1939

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The breeding structure of the purebred Aberdeen -Angus cattle population in the United States from 1900–1939

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THE BREEDING STRUCTURE OF THE PUREBRED ABERDEEN-ANGUS CATTLE POPULATION IN THE UNITED STATES FROM 1900-1939

Howard Sampson Stonaker

A Thesis Submitted to the Graduate Faculty for the Degree of DOCTOR OF PHILOSOPHY Major Subject: Animal Breeding

Approved: A_-^ rge of Ma jor wo rSr1'

ead or Major Department

Dean of Graduate colleg^ Iowa State College 1942

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U M I N u m b e r: D P 1 3 4 9 2

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TABLE OF CONTENTS Page I. INTRODUCTION...............................

1

II. REVIEW OF LITERATURE........................

3

A. Breeding Structure in Relation to Speciation and Breed Formation. .....

3

B. Historical Background of the Breed.......

6

C. Analyses of Other Breeds of Livestock...... III. INVESTIGATION................... A. Method of A

n

a

l

y

s

11 14

i

s

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14

1. Calculation of Inbreeding and Relationship............................

14

2. Analysis of the Aberdeen-Angus Breed....

20

B. Results....................................

21

1. Inbreeding and Inter-se Relationship....

21

2. Effect of Distance as an Isolating Me chanism...............................

27

3. Short Time Fluctuations in the Amount of I n b r e e d i n g

30

.

4. Variations In Numbers of Ties Accumu­ lated During Different Periods of Breed Development ....

39

5. Prominent Animals in the Breed

46

6. Herds In Which the Foundation Animals Were Bred....••••....

62

F 7. Length of Generation Intervals......

66

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TABLE OF CONTENTS (Con't.) Page IV. DISCUSSION..................

*.

V. SUMMARY AND CONCLUSIONS.........

69 76

VI. LITERATURE CITED...........................

78

VII. ACKNOWL32DGMENTS............................

81

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I. INTRODUCTION

The main objective of this investigation and similar ones made in the past has been to describe the breeding structure of a particular domestic breed as based on a statistical analysis of inbreeding and relationships in pedigrees representative of the breed* In the present study, the Aberdeen-Angus breed of beef cattle was chosen partly because of the value of comparing it with the other major beef breeds which have previously been studied, —

the Shorthorn and Hereford.

Objectives

were, first, to find out how much inbreeding has taken place since the breed*s foundation in Scotland.

Second, to what

extent has the breed structure deviated from that expected in a population breeding at random?

Third, what animals

and herds have been the most important contributors to the genetic constitution of the breed?

Fourth, what genetic

importance is attached to the "family” system of nomenclature followed by Aberdeen-Angus breeders?

Fifth, what Is the

average age of the parents of Aberdeen-Angus cattle, and how does this influence breeder*s plans?

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Answers were also needed to the more fundamental ques­ tion concerning the nature of the mechanisms which result in more inbreeding, if any, than would occur if the mating were purely at random.

More specifically, what part do

such factors as distance between breeders and periodic expan­ sion and contraction in breed size have on the relationship between matings?

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II. REVIEW OP LITERATURE

A# Breeding Structure in Relation to Speciation and Breed Formation Evolutionary processes by which domestic breeds and wild populations change appear to be sufficiently alike so that the practical animal breeder may find application for the evolutionary theory and genetic research of workers in the botany and zoology of wild species*

The more important

theoretical aspects of the evolutionary mechanisms making up the breeding structure of a population which may, in part, be applied to the present study are reviewed by Wright (1940).

He points out that the elementary evolutionary

process Is a change of gene frequency which may be brought about in a population by such means as recurrent mutations, selection, immigration, differential emigration, and, if the number of individuals is small, by accidents of sampling the genotype. With the data available In this study, we can only attempt to evaluate the effects of limiting population size on the amount of chance fixation of genes that takes place. It is hoped, however, that the comparative effects of isola­ tion due to distance, geography, and some types of breeder’s

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plans on breeding structure can be deduced from the degree to v/hich these factors affect the inbreeding. Wright (1931) has demonstrated that when there are fewer breeding males than females, the inbreeding expected is more dependent on the number of males than it is on the number of females.

The amount of remaining heterozygosis destroyed

per generation is approximately equal to

_____ 1 & (number of breeding males)

in a population in which there are much larger numbers of breed­ ing females than males.

Assuming, of course, that mating is

random, and that within each sex the animals have the same opportunity to leave descendants.

Another situation tending

to cause the inbreeding to be much larger than the actual poptilation size indicates would exist if different parents produced widely different numbers of offspring.

Also, if there

are tremendous differences in the size of the population frcm generation to generation as with some insects, the number ef­ fective in determining the inbreeding is more nearly estimated by the smaller than by the larger size of the breeding population. Distance as an isolating mechanism increasing the Importance of sampling accidents has also been investigated by Wright (1938). He has shown that random mating does not take place when there are great distances between animals and herds in the population. For example, on a plain on which there are no natural barriers limiting the migrations of animals, some inbreeding results

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from the tendency for animals in the same locality to mate. If the parents of any given Individual are drawn from a region within a given average distance (D) in which there is an effective population size of N, the grandparents would be expected to be drawn from an average distance of fl2D, in which the effective population equals 2N.

The ancestors of

generation nn “ come from an average distance fn D and from a population of average size nN.

The influence of distance

upon differentiation in a continuous population has been shown qualitatively in fish (Thompson, 1931) and in gall wasps (Kinsey, 1929). Dobzhansky (1941) has prepared an excellent review of the Isolating effects of distance and homing Instincts upon the mating habits of a number of species of birds, Insects, mammals, and fish. In purebred cattle populations the importance of such barriers to free Interbreeding as linebreeding, geographic isolation, distance, and periodic fluctuations In popula­ tion numbers are not known as yet, but Wright has set up the mathematical models which may be utilized when the necessary data are accumulated for the analysis of these various factors.

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B. Historical Background of the Breed The Aberdeen-Angus breed originated as a cross between two somewhat similar strains of cattle indigenous to the Scottish counties of Aberdeenshire and Forfarshire (formerly called Angus shire)•

From the historical evidence available

{Sanders, 1928; MacDonald and Sinclair, 1910) the incidence of polledness and of the black color characteristics of the breed was high in these native stocks.

The agricultural

value of these cattle to Scottish farmers lay principally in their use for work stock and the production of feeders to be sold for fattening in the southern counties.

Later

with the development of turnip raising, the cattle were fattened in the northern counties and sold on the English market.

This practice resulted in an increased interest

in the improvement of the cattle through breeding.

The

introduction of the improved Shorthorn bulls for crossing on the native stock became a popular practice, and it seemed for a while that the pure native stock would become extinct.

A few breeders, however, gathered together stocks

of the native strains of the Aberdeen and Angus cattle in order to maintain their purity. Mr. Hugh Watson of Keillor has been considered by his­ torians as the principal founder of the Angus. operations in 1818, continuing until 1860.

He began his

The herd is said

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by William Watson, a son, to have originated with a selection of six of his grandfather’s "blackest” cows and one bull, all polled.

To this foundation Hugh Watson added ten polled

heifers and one bull purchased in Trinity Muir market in Brechin, Angusshire.

Little is knovm of his breeding methods

except that he probably can be considered responsible for setting up the standards of polledness and black color which have become breed characteristics.

It Is said that he con­

sistently weeded out animals which did not have these charac­ teristics, and that he mated "the best to the best, regardless of affinity or blood."

He evidently must have followed some

rather close Inbreeding since It is said that he was tunable to find material outside of his own herd which met his stand­ ards.

William Watson, in his memoirs said, "The three oc­

casions of introduction of outside blood were: in 1841 from Lord Panraure; in 1859 from Alex Bowie; and lastly in President 3

from that grand Balwyllo herd of Mr. Scott.

The two first

were complete failures, the last a perfect success. 3

President

was in service almost up to the Keillor dispersion."

Mr.

Watson advertised his cattle extensively through showing, and they were very successful in Scottish, Irish, English, and French livestock shows.

Some of the animals he bred which

have become important, historically, are Grey Breasted Jock,

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113, Old Jock, 128, Pat, 100, Marquis, 301, Strathmore, 124, Black Jock, 242, Young Hugh, 630, Kaynooth, 63, and Angus, 8 3. Some of the more Important females hred In the Keillor herd ■were Old Grannie, 125, who was the foundress of the families, Kinochtry Princesses, Baronesses, Emilys and Larks of Easter Skene, and Emily, 185, the foundation cow of the Ericas of Balllndalloch.

Considering the Importance of the Watson herd,

hr* Me Comb le of Tilly four has stated that "There is no herd in the country that Is not Indebted to Keillor blood." Other early herds of Importance were those of the Earl of Sou.thesk, Mr. Alex Bowie, hr. George Williamson, hr. Robert 'Walker, Mr. John Marr, Mr. Hector, and Sir Thomas Burnett• William McCombie of Tillyfour has been considered as the most important of the early breeders from the standpoint of Improving and advertising the breed.

It is said that he

founded his herd with Aberdeens from the Williamson and V/alker herds, and Angus from the Watson, Scott, Fullerton and other herds.

His foundation thus appears to be largely the result

of crossing these two strains, combining them into what is now knovm as the Aberdeen-Angus.

Later he acquired such

noted animals as Queen Mother, 41, bred by William Fullerton of Ardestie.

Bulls which he used in his herd were Monarch,

84, Panmure, 69, Angus, 83, and Hanton, 80.

These bulls

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were bred at Ar&estie, 3\eillor, and Mains or Kelly; so it appears that McCombie*s foundation stock was of hetero­ geneous origin.

Eis cows also carie from a large number of

different herds, and it is reported that he purchased choice animals from other herds whenever the opportunity presented itself*

from this foundation he bred many animals that have

been considered important in the development of the breed, such as Charlotte, Rob Roy

MacGregor, Black Prince of

Tillyfo\ir, and Pride of Aberdeen.

McCombie*s system of breed­

ing followed no set pattern; at times he inbred intensively and at other times he used wide outcrosses.

He concentrated

the blood of Panmure in some of the animals in his herd through sire-daughter and full brother-sis ter mating 3.

He

said ”Xn and in breeding may be purstied for a time until the type is developed; hut to continue for any length of time is not only against my experience but I believe against nature. n Ilis outcrossing consisted of the use of Hanton, a Bowie-bred bull, and Angus

(1928) reported that

McCombie*s long period of showring winnings began in 1847 with the winning of Victor, and reached their climax when hi3 group won over all breeds at Paris in 1878. The Ballindaloch herd was probably without rival as far as the length of time which any herd had been continu-

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ousiy bred.

Polled cattle were kept in the estate as long «

as early breeders can remember, but not until about 1860 did additions or pedigreed animals to the old stock begin to be made*

The cow, Erica, has been given a large amount of

credit as a foundation animal in this herd. noted foundation cow in this herd.

Jilt was another

She was the dam of three

great bulls, Juryman, 421, Judge, 473, and Justice, 854. Young Viscount, 181, for a long time considered the best bull in Scotland, was purchased by Sir George MacPherson Grant and used extensively in the herd.

This herd was in

existence until 1934. George Grant of Victoria, Kansas imported the first Aberdeen-Angus cattle into this country in 1873.

The herd

was short lived, being dispersed in 1878. During the period from 1880 to 1883 it was estimated that about 2000 head of Aberdeen-Angus cattle were imported and distributed throughout the United States and Canada. Vif. A. McHenry of Denison, Iowa has been regarded by Sanders

(1S28) as the master breeder of Aberdeen-Angus cattle in America.

For thirty years Mr. McHenry followed the practice

of buying the best cattle that he could bring together for use as breeding stock.

He probably has received the most

acclaim through the breeding of Earl liarshall, 183780, whidi

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is considered as the greatest Aberdeen-Angus sire produced in America (American Aberdeen-Angus.Breeders * Association, 1941)*

The McHenry herd was sold to Charles Escher, Jr.

in 1918 and cattle of the McHenry breeding reached their peak or productivity from 1916-26 under the management and ownership of Escher and Kyan. Briefly summarizing the history of the breed, it seems that the foundation stock was heterogeneous involving crosses of two rather distinct strains of cattle.

The commonly ac­

cepted seedbed of the breed was originally the modestly^ sized herd of Hugh watson in which some d o s e inbreeding was done in order to fix the breed type v/hich he desired. However, a number of other breeders; namely, Fullerton, Ferguson, Bowie, Williamson, Walker, and Scott also were forming foundation herds from the native stocks at about the time of Watson and soon after.

C. Analyses of Other Breeds of Livestock

Wright (1923) made the first breed analysis of this kind in the Bates herd of Duchess Shorthorns•

In that study he

worked out the complete pedigrees of the animals and used his formulae for calculating inbreeding arid relationships as given in 1S22.

For analyzing a representative sample of pedigrees

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in an entire breed in this manner, however, this procedure was an almost impossible task.

As a result, Wright and

McPhee (1925) developed the sampling method of analysis. With this newer method they analyzed the Shorthorn breed. The reliability of the sampling; method was tested by Lush (1S32).

He found that the method was as reliable as its

standard errors indicated, providing no systematic errors were introduced.

Since that tine a number of breeds have

been analyzed by roany different investigators using this same method.

Summaries of these studies are given by

Wlllham (1935) and Carter (1939).

Table I is a tabula­

tion of the results of these studies.

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Table I'Amount of Inbr8©dlng,"EffectiveM Number of Sires and Length of Generation Intervals in Domestic Breeds of Various Countries Genera- Effective" Interval Inbreeding tion number Breed Breed’s studied coefficient intersires per location $otal Per val generation Prom To per cent generation__________________ Cattle: Shorthorn Dairy Shorthorn Jersey Telemark Ayrshire Brown Swiss Hoistein-F*ie slan Brown Swiss Hereford

Gr*Britain Gr.Britain England Norway Scotland Switzerland U. S. A. U* S. A. U. S. A.

1810 1810 1876 1898 1877 1895 1881 1883 1860

1920 1920 1916 1921 1927 1927 1931 1929 1930

26.0 27.5 3.9 2.3 5.3 1.0 4.0 3*8 8.1

1.2 1.3 0.6 0.6 0.6 0.2 0.5 0.5 0.6

Horses: Clydesdale

Scotland

1865

1925

6*2

0.7

Sheep: Rambouillet Hampshire

U. S. A. B» S. A,

1892 1911

1926 1935

5.5 2.9

0.7 0.9

4.2 3.7

18 14

Swine: Landraoe Poland-China

Denmark U. S. A*

1897 1880

1930 1929

6.9 9.8

0.5

2.2 2.5

25

0.6

4.7 5.4 5.4

10 10 21 21 21 45*75 27 31 21 18

20

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III. INVESTIGATION

Am Method of Analysis

1* Calculation of inbreeding; and relationship Wright devised the .first genetically acceptable method of measuring the amount of inbreeding which results from mating relatives other than regular full sib mating or selffertilization*

His measure of inbreeding indicates the

percentage of those genes heterozygous in the population at a designated time which have probably become homozygous through consanguineous matings.

It Is thus a measure of the

decrease In heterozygosity relative to whatever amount of heterozygosity existed In the population at some base date* This Increase in homozygosity can be calculated for any complete pedigree by the following general formula, which is explained by Wright (1922)* Fx = The inbreeding of animal x * a [(s)n+ 2

(1+JEra)].

= Summation of* n - The number of generations from the sire to the common ancestor.

n* — The number of generations from the dam to the common ancestor. Fa = The inbreeding of the common ancestor*

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Briefly, the genetic theory behind the formula Is that the formula summarizes the total probability of two Identical genes from the germ cells of a parent coming together again as alleles In a descendant in a subsequent generation.

Un­

less there be ancestors common to both sire and dam a decrease In heterozygosis from this process cannot take place. The labor of computing the inbreeding for a large num­ ber of animals, such as a representative sample of a breed would be exceedingly great if one were to calculate the total inbreeding in the complete pedigree of each animal.

Thus

the Wright and McPhee (1925) method of sampling pedigrees was used here in order to obtain an unbiased estimate of the average inbreeding of the animals in the population.

The

detailed procedure of this method is given by Willham (1955). Using the sampling technique, and one random line traced from the sire and one from the dam of each animal In the sample, the average Inbreeding of a population at any one time be­ come s : Fb = The average Inbreeding of the breed =

N

.50 (1 + Fa) if 55 The total number of pedigrees In the sample.

The reliability of the average inbreeding percentage Is mea­ sured by Its standard error. The formula for the standard error

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term as given by Wright (1925) Is equal to/pq 3c F^> * H

in which

pT“

p s Fraction of the pedigrees with ties* q s Fraction of the pedigrees without ties* Fh = Inbreeding of the breed. N = The number of pedigrees In the sample* Wright (1922) describes the method of calculating rela­ tionship between any two pedigrees*

His general formula for

calculating relationship is:

R^y = Z [(A)11-1-”' (1+ Fall /1+ Fx

4 1+

Py

RXy s The relationship between two animals x and y* n

- The number of generations between x and the common ancestor*



r The number of generations between y and the common ancestor*

Fa

=The inbreeding

of the commonancestor*

Fx

=The Inbreeding

of x*

Fy

-The inbreeding

of y*

Thus the formula represents thechance

for duplicate

genes from a common ancestor to appear in any two descendants. This relationship formula also has been adapted to sampling methods by Wright and MePhee (1925)*

The details concerning

the arrangement of the pedigree sheets and the method of sampling are described by Wlllham (1955)•

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The average Inter-se

relationship measures in terms

of correlation the genetic likeness "between animals relative to that existing among the ancestors present at a designated base period*

The average genetic likeness among the animals

at that base period is taken as the zero point upon which to base the measure of likeness among their descendants* The object of tliis measure is to evaluate how much the genetie similarity between animals in closed populations such as breeds has increased since the base date* The formula for calculating the average inter-se rela­ tionship within a breed iss

Rb * Average inter-se relationship within the breed. Fa s Inbreeding of the common ancestor* N

r The number of possible ties betweenanimals*

Fb - Inbreeding of the breed. The formula for the standard error (Wright, 1925) Is similar to that for inbreedings x

Rb ~ r

Relationship of the whole breed to individual ancestors measures the extra genetic similarity of certain ancestors to the breed as compared to the average relationship among animals at the base date*

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Relationship may be divided into the direct, and collat­ eral relationship.

Direct relationship is that which comes

about because one animal is the ancestor of the other.

Col­

ateral relationship is that which comes about because both animals are descended in part from some of the same ancestors. In the sampling process the direct relationship Is measured as follows: D.R. = (Humber of lines to the breed) (l^Fq) 2N /!+ Fb I /i+ F c Fc

- The inbreeding of the animal itself. - The Inbreeding of the breed.

Collateral relationship is measured as follows: C-R«* £ g w ) (ln-Pa) (L)\ 2N / T T F b . fl+ F c ^a

*

Inbreeding of each ancestor.

W

=

The weight given the lines depending on the direct relationship of the animal to Its ancestor through which comes Its collateral relationship to the breed. For instance W • .5 when the ancestor is a parent * .25 when the ancestor is a grand­ parent •

L

=

Humber of lines from ancestor to breed but not through the son or daughter through which It is directly related to the animal in question*

Following is an example of part of a pedigree and the calculation of the total relationship of an animal to the breed.

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5c 6c Oc 66d

Hetf < r -p

O E-*