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THE RELATIONSHEP SW’EEN A. L SER£$ AND
THE INDEX. VALUE OF THEIR DAMS
'T‘Emsis for ‘25:; Degree. c§ M. S.
MECEESAN STATE SPRU’ZRSZ'E‘Y
Robert W. Everett
1963
LIBRARY
I Michigan State
University
THE RELATIONSHIP BETNEEN A. I. SIRES AND
THE INDEX VALUE OF THEIR DAMS
By
ROBERT W. EVERETT
AN ABSTRACT
Submitted to the College of Agriculture
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
Department of Dairy
Year 1965
) _~ . 1 A
Approved _ _ :29] 7:41.] _(:-v_ 27.11.— .. fiat-k. _. ._ _
ABSTRACT
THE RELATIONSHIP BETJEEN A. I. SIRES AKD
TEE IEDEX VALUE OF THEIR DAKS
by Robert N. Everett
To study the value of selection indexes in a Young
Sire Program, 126 artificially proven sires which met the
qualifications of having at least 25 artificial daughters,
5 natural daughters, and pedigree information on the dam
of the bull and her relatives were used. The dam's side
of the pedigree was completely analyzed by compiling all
the available production records on (1) the bull's dam,
(2) the dam's dam, (5) the dam's daughters, (4) the dam's
maternal sisters, and (5) the dam's paternal sisters. All
records were converted to a 505-day, 2X, mature equivalent
basis and were deviated from the 505-day, 2X, mature equi-
valent herd average.
The 126 cows (dams of the bulls) had 704 lactations
which averaged 1,420 pounds of milk above herd average for
all records and 1,847 pounds above herd average for first
records. There were 79 dams with 585 lactations which
averaged 1,452 pounds of milk above herd average for first
records and 1,117 pounds of milk above herd average for
all records. The 258 daughters had 1,045 lactations which
Robert W. Everett
had an average deviation of 684 pounds of milk for all
records and 1,176 pounds of milk for first records. The
171 maternal sisters had 758 lactations with an average
deviation of 551 pounds of milk for all records and 947
pounds above herd average with first records. There were
5,910 paternal sisters which averaged 186 pounds of milk
above the herd average.
The A. I. Proofs ranged in numbers of daughters
from 25 to 1,526 and from 5 to 120 daughters for the
Daughter-Dam Comparison and the Natural Proof. To correct
for unequal numbers, the A. I. Proofs were regressed with
the factor N/(N + 12) and the two non-A. I. Proofs were
regressed by the factor N/(N + 16).
The dams of the bulls were indexed using first
records and the average of all records by McGilliard's
(1962) selection index. The index using first records
correlated with the A. I. Proof + .148 and the index using
all records with the A. I. Proof + .149. The dam's index
correlated approximately one half as much as the correla-
tion between the A. I. Proof and either non-A. I. Proof.
If the sire's side of the pedigree would yield as
much information as the dam's side, a complete pedigree
with information on the dam and a sire which has an A. I.
Robert W. Everett
Proof may yield as much information on a young sire as a
Natural Proof could yield.
The advantages of a young sire program are: (1)
high selection intensity, (2) lower initial cost per sire,
(5) an earlier A. I. Proof on the sire, and (4) a longer
A. I. service life.
THE RELATIONSHIP BETﬂEEN A. I. SIRES AND
THE INDEX VALUE OF THEIR DAMS
By
ROBERT W. EVERETT
A THESIS
Submitted to the College of Agriculture
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE
Department of Dairy
Year 1965
ACKROJLEDGEKELTS
The author wishes to express his appreciation to
Dr. Clinton E. Headows for his patient guidance and con—
structive criticism during the investigation of the prob-
lem and writing of the thesis.
Thanks are also due to Dr. Lon D. hodilliard for
his willing counsel and technical assistance throughout
the course of the study and in the analysis of the data.
The author is grateful to hr. Alvin J. Thelen for
his aid in machine processing portions of the data.
ii
TABLE OF CCNTEETS
Page
INTRODUCTION . . . . . . . . . . . . . . . . . . . . 1
REVIEJ OF LITERATURE . . . . . . . . . . . . . . . . 5
Sire evaluation . . . . . . . . . . . . . . . 5
Selection indexes . . . . . . . . . . . . . . 17
SOURCE F DATA . . . . . . . . . . . . . . . . . . . 52
METHODS AND RESULTS . . . . . . . . . . . . . . . . 56
Standardizing the records . . . . . . . . . . 56
Indexing the bulls . . . . . . . . . . . . . 57
Components of variance . . . . . . . . . . . 42
DISCUSSION . . . . . . . . . . . . . . . . . . . . . 50
SUMMARY . . . . . . . . . . . . . . . . . . . . . . 59
LI TE "a TUIE CITE o o o o o o o o o o o o o o o o o o 62
iii
TABLE
10
11
12
15
LIST OF TABLES
The Comparison of A. I. and Ron-A. I.
Sires O O O O O O O I 0 O 0 0 O O O O O O 0
Repeatability of Averages of Lactations . .
Correlations Between Bulls' Daughters and
Bulls ' Relatives O O O O O O O O O O O O 0
Numbers and Averages of Lactations . . . .
Index Weights for a Cow with 5 Daughters,
4 Iaternal Sisters and 6C Paternal Sisters
Correlations, Means and Standard Devia-
tions of Indexes and Proofs . . . . . . . .
Variances, Covariances, and Correlations
USing All Records 0 O O O O O O O O O O O O
Variances, Covariances, and Correlations
USing E‘irst Records 0 O O O O O O O I O O 0
Components of Variance--First Records . . .
Components of Variance--A11 Records . . . .
Heritability Estimates . . . . . . . . . .
Indexes Above Two Standard Deviations and
the Son's A. I. Proof . . . . . . . . . . .
Heritabilities of Lactation Records . . . .
iv
Page
15
18
19
54
41
42
44
45
47
49
55
Figure
Chart
1
Page
Path Diagram Indicating the Theoretical
Correlations Between the Phenotypes and
Genotypes of the Young Sire and Its Close
Relatives O O O O O O O O O O I O O O O C O 59
LIST OF CHARTS
Distribution of Lactations . . . . . . . . 55
INTRODUCTION
Genetic improvement in milk production in dairy
cattle can be achieved by culling the poor cattle and sav-
ing offspring of the superior individuals. The genetic
superiority of an individual can be estimated by its pedi-
gree, its own performance, and its progeny. To evaluate
the genetic potential of the sex-limited trait in the non-
producing male involves consideration of the pedigree and
progeny. Individuality and ancestry furnish the only
basis of selection for a young bull calf. Type is little
correlated with production, and this leaves the study of
the ancestry as the main basis of selection.
The present trend in Artificial Breeding units (A.
I.) in proving bulls is the "Ybung Sire Program." The
procedure is to select the best young bulls to test and to
do the final selection after the tests are available.
From a large number of young bulls, it is prOposed to sort
out the bulls of highest potential merit by the use of a
selection index which weights the records of the ancestors
to estimate best the genetic potential of the bull. The
final selection of the bull for extensive use would be on
the A. I. proof.
The young sire would be the son of a selected and
superior proved A. I. sire whose proof would be an accurate
_ 1 _
indication of his genetic ability. The dam, however, may
have few records, and her production alone may not yield
the best estimate of her genetic ability. Thus, the ac-
curacy of the selection of young sires seems to depend on
how accurately the dam's genetic ability can be predicted.
The purpose of this study is to evaluate the accu-
racy and usefulness of available selection indexes in
selecting dams of young sires.
REVIEH CF LITERATURE
Sire evaluation
Professor Nils Hansson, in 1915, suggested that a
rating of sires for fat percentage could be obtained by
placing the daughters half-way between the sire and dam.
No method of rating sires on milk quantity was proposed.
The first sire index published as a commercial advertise-
ment was the Mount Hope Index by Dr. Hubert D. Goodale in
1927. This index had the feature of doubling the differ-
ence between daughters and dams to predict the bulls
genetic ability for milk, fat, and fat test (Prentice,
1955).
Rice (1955) suggested the following three standards
be met by sire indexes: (1) the index must be simple and
easily understood by the average dairyman, (2) it must
employ both the dams' and daughters' records, and (5) it
must be a definite numerical statement of the bull's
potential.
In the United States there are many and varying
methods used to evaluate a bull's genetic ability. These
usually vary with location and involve different adjustment
factors for seasons, years, and number of progeny.
O'Connor (1962) has outlined the methods used in EurOpe
-5...
which range from the daughter-dam comparison used in
France to the progeny testing stationSIHxﬂ.in Denmark.
The basic types of proofs are: (l) the sire's
daughter level or the average 5OS-day production of the
sire's daughters, (2) the daughters' production minus
their contemporary stablemates' average production, and
(5) a comparison of daughters with their dams. There are
many modifications of the ones listed above being used in
the United States and EurOpe.
Edwards (1952) evaluated five methods of expressing
a progeny test: (1) the daughter-dam comparison, (2) the
Equal Parent Index, (5) the Mount HOpe Index, (4) a regres-
sion index, and (5) the average production of the daughters
of a bull. The index which most closely approached the
ideal was the average production of the daughters of a
bull without reference to the dams' records. The minimum
number of daughters necessary for an accurate index was
six.
Gaunt and Legates (1958) studied five measures of a
sire's transmitting ability using 6,949 daughter-dam pairs
in 2,420 herds. The five measures were: (1) the daughter
average, (2) the daughter-dam difference, (5) the equal-
parent index, (4) the daughter-contemporary herd differ-
ence, and (5) the daughter-contemporary herd index.
Contemporary DHIA herd averages were used in (4) the
daughter-contemporary herd difference and (5) the daughter-
contemporary herd index. Correlations between each of the
five measures and the average of a specific number of fu-
ture artificially sired daughters were computed. The
daughter average appeared to be about as reliable as the
equal parent index or the daughter-herd index in predicting
future production of daughters. As the herd average in-
cluded the daughters in question, using a contemporary
herd average which excludes the daughter in question in the
two daughter-herd measures should improve their accuracy
as a measure of a sire's breeding value.
O'Bleness 23 gl. (1960) compared the New YOrk
method with 17 other methods of ranking A. I. sires. The
New York procedure is the most difficult computationally.
Correlations were estimated between sire estimates for each
procedure and the New York method which was used as the
control. The 17 procedures were put into five groups.
Group 1 included deviations of the daughters' averages
from various contemporary averages; Group 2 was deviations
of averages of first records from contemporaries; Group 5
was the percentage of average records exceeding contempor-
aries; Group 4 was percentage of first records exceeding
contemporaries; and Group 5 was actual averages and actual
averages adjusted for stablemates. When all sires regard-
less of the number of daughters were included, Group 1
correlations with the New York method were about .77;
Group 2, .69; Group 5, .69; and Group 4, .47. Unless the
number of daughters is large, none of the procedures ranks
the sires the same as the New York method. If adjustment
is made for the number of daughters, the correlations all
increase, but correlations for Group 1 are still the
largest.
Touchberry gt El. (1960) studied first lactation
milk and butterfat records of 5,454 daughters of 505 Red
Danish Milkrace sires tested at Danish testing stations
and the first test year milk and fat records of 5,270
daughters of 110 of these same sires tested in farmer
herds. Heritabilities of milk and fat at the test stations
were higher than in the farmer herds. The genetic corre-
lations between station tests and field tests were .68 for
milk and .75 for fat. Independent field tests had genetic
correlations of .94 for milk and .92 for butterfat. It
was shown that the field test was superior for milk and
fat if the number of daughters per sire was seven or more
and fifteen or more, respectively. Selection on the test-
ing station data was superior if there were less than
seven daughters per sire for milk and less than fifteen for
fat. For twenty daughters per sire, the field test was
1.14 and 1.02 times as effective as the station tests for
milk and butterfat, respectively.
In New York, bulls are sampled and subsequently are
selected on the basis of their progeny tests. Heidhues
23 gl. (1960) studied the validity of this procedure of
sampling bulls which depends upon the assumption that the
daughters of a sire are a representative sample of all
possible daughters. The actual proof was computed accord-
ing to the method develOped by Henderson. The data included
55 Holstein sires with at least 500 daughters each. The
correlations were only slightly lower than the expected
correlation from a sample of all possible daughters.
Berry (1952) proposed a plan in which each record
would be expressed as a percentage of the breed class
average. The system of breed class average (BCA) is pre-
sently used for age correction in Canada. The actual
breed averages have been computed by ten-day intervals
according to age from data over a five-year period. Offi-
cial lactations are reported and are expressed as a per-
centage of the BCA for milk and for butterfat for 505 days.
The daughters of a sire would be compared with their dams
on the basis of percentage above or below breed average
used in the equal parent, regression, or expectancy indexes.
8
Barr (1962) expressed his data on a BCA basis in his analy-
sis of the selection of young sires.
Wilcox (1960) obtained the coefficients of variation
of 9.64, 11.48, and 15.26 for the daughter average, the
difference between daughter and herd average, and the con-
temporary comparison, reSpectively, as methods of testing
sires. It was concluded that the method of the daughter
average was easily the first choice among the three
methods studied. It had the lowest coefficient of vari-
ation, is easiest to compute and makes use of all the data
whereas some individual records may not be used in the
other methods. The difference between daughter and herd
average was second and the contemporary comparison third.
The contemporary comparison method was criticized in that
it may not make use of all single records.
From the regression of future daughters on present
daughters, it was concluded by Wilcox (1960) that the
first twenty daughters give a reliable estimate of the
production of the future daughters under conditions of
random mating and random distribution of daughters in
tested herds.
Sendelbach 23 gl. (1957) studied the number of A. I.
daughters necessary to predict a sire's A. I. performance
and the repeatability of natural service daughter averages
in A. I. Fifty-one sires with 100 or more A. I. daughters
were used. The first 50 daughters as well as the fifty-
first through the one hundredth were regressed on the
first 5, 10, 15, through 50 A. I. daughters. Both methods,
the first fifty and the second fifty daughters, yielded
similar results which indicated that 20 to 50 A. I. daugh-
ters are sufficient to estimate future A. I. daughters
with reasonable accuracy. The first 50 A. I. daughters
were regressed on the first 5, 10, 15, through 50 natural
daughters. The results showed that the ability to predict
the performance of A. I. daughters from natural service
records is low, approximately one half that achieved in
artificial service. The regression coefficient of future
daughters on the first 25 daughters was .61 which equals
N/(N + 16), if no environmental correlations are present.
Specht (1957) measured the regression coefficient
of A. I. future daughters on N tested A. I. daughters to
be N/(N + 11.9) for milk and N/(N + 16.4) for fat. Specht
also cited Legates gt El. (1956) as obtaining values of
N/(N + 16) for milk and N/(N + 15.8) for fat. Robertson
and Rendel (1950) were cited as using the regression of
N/(N + 15) when heritability equals .25. Carter was cited
as finding a regression of N/(1.1N + 14.9) with one record
per cow from New Zealand. Henderson was cited as using the
factor N/(N + 12).
lO
Lush (1955) demonstrated that the superiority of
the progeny test over the individual's phenotype for a
given trait is greatest where heritability is low and
under conditions where the offspring do not resemble each
other for reasons of having been under common environ-
mental conditions. If the trait is highly heritable or
the progeny resemble each other very much, then many more
than four daughters will be needed to equal the individu-
al's own phenotype and under certain conditions it is im-
possible to equal the individuals own phenotype. The pro:
geny test is needed in a sex-limited trait, as in milk
production in dairy cattle. For traits which the sire
cannot express, there is nothing but a pedigree estimate
of the sire against which to compare the accuracy of a pro-
geny test. A progeny test surpasses the best pedigree
estimate when there are three or more progeny except where
the offspring resemble each other very closely. In actual
practice the pedigree becomes available first and progeny
testing comes last. Care should be taken not to let early
selection on the pedigree exhaust selection on the progeny
test.
Barr (1962) has shown that very complete pedigree
information on a young sire gives as much information as
records on eight daughters of the bull. Lush and
ll
McGilliard (1955) estimateithat usually four or more off-
spring are needed to be of more value than the individu-
al's own phenotype. Lush (1951) has shown that when there
are as many as 4 to 6 offSpring in a progeny test, the
test will be about as accurate as an estimate based on a
very complete pedigree. A pedigree would be more reli-
able than a progeny test if a bull's daughters in one herd
are given very poor care compared to other bull's daughters
which had very good environmental conditions. When en-
vironmental conditions for all cows are made as uniform as
possible, the progeny test can approach perfection.
Lush and McGilliard (1955) have shown the amount of
bias which is caused by the selection of N daughters with
the largest records as compared to using all the daughters
in a proof. Selection of a sire's mates will generally
have been more intense than the selection of the daughters,
but it introduces less bias. To use only the highest
record of a cow is to say that her genetic ability is ex-
pressed most adequately in an environment which gives a
superior phenotypic expression. The amount of bias for
many combinations of selected records are given. Using
the best record is especially unfair for comparing individ-
ual cows since all cows have not had an equal chance to be
exposed to a superior environment.
12
Lush and McGilliard (1955) indicated that to correct
for herd to herd differences which are estimated to be 80
to 90 percent environmental and 10 to 20 percent genetic,
usually records are expressed as deviations from the herd
~average. Robertson gt _l. (1961) using data from England
and Wales found that the mean contemporary comparison de—
clined with increasing mean level of production. This de-
cline was such as to imply that 20 percent of the differ-
ences in production between herdswnre genetic in origin.
Robertson and Rendel (1954) showed that A. I. bulls
selected from elite herds are not genetically superior to
a random sample of non-A. I. bulls in average herds, in-
dicating that the management level is superior in the elite
herds. Iirchner (1959) showed the heritability of herd
differences to be .11.
Lush gt _l. (1941) discussed the major sources of
error and the magnitude of the error in estimating breed-
ing values. Bias due to differences in selection inten-
sity and the use of lifetime averages was also discussed.
Carter (1961) studied the sampling of young sires
in high herds and a random sample of all herds. Thirty-
three Holstein sires with 100 or more tested daughters were
r
selected. The daughters' records were expressed as devi-
ations from their contemporaries and were divided into 5
15
equal groups from high to low, according to production. A
regular daughter study was made independently. The records
of 19,652 A. I. cows from 55 sires with a minimum of 20
daughters per group per sire were used. The sires were
ranked according to the butterfat production of their
daughters using the New York method with adjustments for
herds, years, season of calving, and number of daughters.
These data indicated that young sires can be sampled in
elite herds and still be ranked with a reasonable degree
of accuracy. High or low herds are less desirable than
the average level herds for sampling young bulls.
From the progeny tests of sons from superior and
inferior parents, Varo (1959) found that the "relative
evaluation method" (based on deviations from herd averages)
is a more accurate guide to the breeding value of a sire
for milk yield than the actual average yield of his daugh-
ters. This accuracy would be expected to increase in the
future if artificial breeding reduces the existing genetic
differences between herds. It was found that the accuracy
of the progeny test based on a given number of daughters
was greater in herds of higher production. However, it
was also found that the ranking of different bulls was
similar at different production levels. The average fat
content of the milk in the herd had no influence on the
accuracy of progeny testing for milk yield.
l4
Fifty-seven Friesian, 8 English Ayrshire, and 11
Scottish Ayrshire A. I. bulls with at least 100 "effective
daughters" were analyzed by Robertson gt gt. (1961). The
herd-years were divided into 5 equal groups on the basis
of the average heifer yield of both daughters and con-
temporaries (high, medium, and low producing herd-years).
Three independent contemporary comparisons were calculated
for each bull. The variance between and within sires in-
creased with the mean level of production, but almost ex-
actly in parallel with each other such that the heritabil-
ity, and, consequently, the accuracy of the progeny test
for milk yield was effectively the same at all production
levels.
Van Vleck gt _l. (1961) analyzed deviations of
records from different contemporary averages according to
the following model:
Yijk = u + hi + Sj + eijk
where E is the 5-year breed-season average, hi is the ef-
fect due to the tth herd-year-season, ii is the effect due
to the 1th Sire, and ei‘k is the random element assoc1ated
with the 'jkth record. The components were assumed to be
independent and to have zero means. The four types of
deviations were: (1) regressed adjusted stablemate aver-
ages, (2) adjusted stablemate averages, (5) stablemate
l
averages (all records made in the herd, excluding the cow
and (4) herd averages (includes the record of the cow).
The prOperties of the best model included: (1) unbiased-
ness and (2) an estimator with a small variance. The
first three procedures give unbiased rankings of the sire
effects. The fourth is biased by a factor which depends
on the number of stablemates. If the bias were constant,
the ranking would not change. The smallest variance of a
deviation is given by the fourth method, but this method
is the only one that gives a biased estimate of the rank.
In the unbiased ranking procedures, the smallest variance
is given by the deviations from regressed adjusted stable
mate averages. This method was considered the best of th
four.
TABLE 1
The Comparison of A. I. and Non-A. I. Siresa
5
).
e
_——
No. of No. of No. of Superiority
Breed A.I. Bulls A.I. Daus. Nat. Daus. of A. I.
Friesian 14 352 403 +26 i 15
Shorthorn 31 805 975 -5 i 6
Guernsey ;; __g§§ __§2; -14 + 10
A11 56 1,425 1,729 +1 1 5
aRobertson and Rendel, 1954.
l6
Robertson and Rendel (1954) analyzed the performance
of heifers sired by A. I. and natural service. A large
percentage of the A. I. bulls were pedigree bulls, and
those that were not generally had a pedigree sire. The
A. I. animals produced almost exactly as much as the non-
A. I. animals in the same herd. In fat percentage the A.
I. animals were superior in all breeds. The A. I. bulls
were not genetically superior to the non-A. I. bulls in
milk yield.
Tucker gt gt. (1960) used 6,888 records in North
Carolina and found first lactation contemporary comparisons
showed A. I. progeny to average 566 pounds of milk and 15.7
pounds of fat more than naturally sired progeny.
Wadell gt_g;. (1960) found that first lactation
records of A. I. daughters averaged 199 pounds of milk and
2.5 pounds of fat below the herd average. The second
records of A. 1. daughters averaged 50 pounds of milk and
4.5 pounds of fat above the herd average.
Specht (1957) utilized information from 54,075
Holstein cows and found evidence to suggest that bulls
used by the A. I. studs have not substantially increased
the milk producing ability of the pOpulation.
In herds of less than 100 cows, progeny testing was
less efficient than selection of young sires based on the
17
production of their dams (Specht, 1957). Progeny testing
had a slight advantage in herds of 100 to 200 cows. Pro-
geny testing in A. I. populations of 2,000 to 10,000 cows
gave evidence of making possible 1.5 to 2.5 percent annual
genetic gain of the average annual yield. A progeny test-
ing scheme with young sires was estimated at 1.7 to 1.8
percent annual genetic gain of the annual yield. It was
concluded that the most reliable method of improving the
genetic merit of the dairy population was the selection of
young sires and the saving of the best of these young
sires. Seath (1940) showed the indicated hereditary im-
provement resulting from culling cows to have a range of
25 to 58 pounds of milk and .28 to 1.55 pounds of fat per
year. In contrast to the predicted annual genetic gain
from progeny testing sires, culling cows would yield an
annual genetic gain of approximately .2 percent of the
average annual yield.
Selection indexes
Wright (1940) outlined the principles underlining
progress in livestock breeding. In the simple case, with
many factors making the same additive contribution, there
would not be any dominance and no environmental variabilitm
Under these conditions, selection of the best animals
should give the most rapid progress. The average
18
contribution of the gametes is indicated directly by the
character of the individuals and any attention to pedigree
or progeny tends to weaken the estimate of transmitting
ability. Mating of unrelated animals maintains variability
on which further progress depends. Much more progress is
possible if the variability is due to multiple minor fac-
tors than if it is due to a few major ones. If there is
a great deal of uncontrollable nongenetic variability, the
character of an individual gives little information of its
actual transmitting ability. The pedigree should be used
as a preliminary test followed by a progeny test. The pro-
geny should be from an unselected group to eliminate bias.
Lush (1957) showed that later records of high or
low cows were not as high or low as their first records.
TABLE 2
Repeatability of Averages of Lactationsa
1
‘1
No. of Records Repeatability
1' .40
2 .57
3 .65
aLush, 1957.
19
The data indicated that the major source of confusion in
breeding selections are temporary things which can cause
a cow's record to be high in one lactation and low in the
next lactation. If dominance and nicking play a part, the
data indicate that part usually to be a small one.
Copeland (1951) studied 694 Jersey cows which had
at least one tested daughter and one R.0.M. son. The
highest record of each cow was converted to 565-day mature
equivalent basis by 1.15 factor. The correlation between
the dam's record and daughter's record was .404. A cow's
record was nearly twice as reliable a measure of the pro-
duction of her daughters as was the production of her sons.
This may have been due to the fact that the daughters of
TABLE 5
Correlations Between Bulls' Daughters
and Bulls' Relativesa
“— 4. j
— 1 ‘—
Relationship Bull's Daughters
Sire .558
Dam .551
Paternal Grandsire .250
Maternal Grandsire .427
5+ Maternal Sisters .466
2 Maternal Sisters .578
l Maternal Sister .557
aCOpeland, 1954-
20
the cow were in the same herd and the son's daughters were
in several herds, and corrections were not made for environ-
mental differences. In general, the daughters showed about
52 percent as much variation from the breed average as did
the dams.
Dickey and Labarthe (1945) studied the transmitting
ability of young dairy bulls. The only criteria for
selecting young bulls were pedigree and individuality.
Using pedigree information, the data were analyzed accord-
ing to Rice's Regression Index by regressing the sire's
proof and the dam's records toward the breed average by a
factor of .5. A second method used was to average the
sire's proof and the dam's records. The regression method
was superior in predicting milk and butterfat production
of the daughter of the sire. The two methods are about
equal in predicting butterfat test.
Eldridge and Salisbury (1949) studied the relation
of pedigree promise to the performance of proved sires.
The variables used were the mates of the bull, the maternal
half sisters of the bull, the dam of the bull, the paternal
half sisters of the bull, the dams of the paternal half
sisters, and the paternal half sisters of the bull's dam.
Forty—four percent of the total variance among bulls was
accounted for by the mates of the bulls or the dams of the
21
bull's progeny. The data were analyzed in the form of
actual production records, thus differences between herds
would probably account for a large amount of 44 percent of
the total variance among bulls.
Multiple correlation squared (R2) was .491, thus
the other variables accounted for about 5 percent of the
variance. The records of the dams could have been removed
from the equation without affecting the results. There are
no data within this study to evaluate properly the records
of the dam in selecting the bull. The maternal half sisters
of the bull or the daughters of the dam of the bull were
deleted without affecting the prediction value of the
equation (R2 = .490). There were only 1.85 maternal half
sisters per bull compared to 20 paternal half sisters.
The study indicated that the female relatives are
of importance in the following order:
1. Average production of the paternal half sisters.
2. Average production of the dams of the paternal
sisters.
5. Average production of the paternal sisters of
the bull's dam.
4. Average production of the bull's dam.
5. Average production of the maternal sisters of
the bull.
22
The bull's dam and the maternal half sisters of the
bull showed almost no phenotypic relationship to the bull's
daughters.
In farm animals, records on the sire and/or the
dam are useful when early selection is desirable or when
additional accuracy beyond the individual's phenotype is
required. Young (1961) calculated the theoretical corre-
lations between an individual's genotype and its relatives'
phenotypes. The superiority of the selection index system
over selection on an individual's phenotype was shown to
be greatest where there are a large number of records on
each individual and where heritability is small. When
heritability is large, the gain by combined selection is
small.
Lush (1947) compared individual merit, family merit,
and the optimum combination of some attention to individual
merit plus some attention to the average merit of the
family as a basis of selection. The correlation between
breeding values of members of a family (3) and the corre-
lation between phenotypes of members of a family (3) must
be very unequal if combination selection is to make much
more progress than would be made by mass selection alone.
Where a is far larger than 3, adding family selection
properly to mass selection will increase the gain consider-
ably. Where t is far larger than 3, considering family
23
merit also will increase considerably the effectiveness of
selection, but the attention to family merit should be
negative. when t is very small, family selection and com-
bination selection are nearly equal, their advantage over
mass selection increasing distinctly with larger family
size. At intermediate levels of t combination selection
is distinctly better than either of the others but less
is gained by making E large. Under all conditions the
combination method is at least equal to the other methods,
but at some values of p and 3 its superiority is hardly
enough to make the extra computations worth while. The
combination is most superior when 3 is moderate and t is
much smaller, but yet well above zero, and where t is dis-
tinctly larger than 3. Making E large increases the ef-
fectiveness of family selection and of combination selection
markedly only where t is extremely small and g is very
large. Inbreeding will increase the effectiveness of
family and combination selection markedly, mainly by in-
creasing 3. Finally, family selection is most superior to
mass selection when family members resemble each other
least or where t is small.
Hazel and Lush (1942) compared three methods of se-
lection: (1) the Tandem Method, (2) the Total Score
Method, and (5) Independent Culling Levels. The Total
Score Method is the most efficient, while the Tandem
24
Method is the least efficient of the three. A total score
based on 5 equally important, uncorrelated traits is VET
times as efficient as tandem selection for the same traits,
one at a time. The progress made in any one trait by the
Total Score Method is only l/Wﬁ'times as much as if selec-
tion were directed at that trait alone.
Hazel (l945),in his paper on selection indexes,
shows the Opportunity for making progress depends upon mak-
ing the correlation between the index and the genotype of
the animal (RIH) as large as possible. (H represents the
sum of an animal's several genotypes.) Accordingly I is
defined as: I = lel + b2X2 + ----- + ann, where the
X's represent the phenotypic performance of the several
traits and the b's are the partial regression coefficients
chosen as to make RIH as large as possible. These regres-
sion coefficients are calculated from E simultaneous equa-
tions. The statistics needed for construction of an index
are: economic value of the trait or traits, standard devi-
ations of each trait, phenotypic correlations between the
traits of relatives and genetic correlations between the
traits of relatives. ﬁright's method of path coefficients
is convenient for calculating the more complex correla-
tions between H and the phenotypic performance of the
traits. To measure the genetic correlation (rGiGj) was to
correlate one trait (2) in one animal (i) with the other
25
trait (l) in a relative (j). A - _
=¢EiEJl-53211 covi2 l cov'2il
bi2il.bj2jl ‘ covi2il covj2jl
was adopted because it was unbiased. The amount of genetic
The formula rGiGj
progress expected when a given index is used in making
selections is pr0portional to RIH’
Tabler and Touchberry (1959) used 20,024 single
daughter-dam pairs in 1,705 different herds in construct-
ing a selection index for milk and fat. A selection index
for milk alone would be expected to be most effective in
improving milk and fat yield in dairy cattle due to the
genetic correlation between milk and fat of .77.
Tabler and Touchberry (1955) used 2,810 daughter:
dam pairs in 414 herds with production records and type
classification in constructing a selection index based on
milk, fat, fat percentage and type classification. The
first single record was used and adjusted to mature equiva-
lent. Selection on other traits reduced the increase in
milk production, especially when type was included in
the index, since .07 was the genetic correlation between
milk and type.
An index for intra-herd selection for fat production
was derived by Legates and Lush (1954), utilizing the fat
yields as deviations from the herd average of the cow, her
dam, daughters, maternal sisters, and paternal sisters.
26
Statistics to construct the index were computed from
25,550 lactation fat yields of 12,405 Jersey cows on
H.I.R. test. The intra—herd statistics needed to construct
the index were: repeatability, .412; correlation between
maternal half sisters, .075; correlation between paternal
half sisters, .12; and heritability, .201. Herd differ-
ences accounted for 59 percent of the total variance.
Within herds, the year-to-year variation in things which
affected all cows alike accounted for 8 percent of the
variance. A cow's records were weighted according to the
number of records to get her true producing ability. The
variance of averages of N records is (l + (N - l)V)/N times
the variance of a single record, where 1 is the repeata-
bility of records of the same cow. Each cow's phenotype
should be multiplied by the inverse of its variance,
N/(l + (N - l)V) to be weighted prOperly. A convenient
way of accomplishing this weighting was to express each
cow's phenotype as her most probable producing ability:
[NV/(l + (N - l)Vﬂ (cow's average - herd average)
The index derived was: I = X1 + .4X2 + b5X5 + b4XA + b5X5;
where X1 and X2 are the real producing abilities of the
cow and her dam and X3, X4, and X5 are the sums of the
real producing abilities of the cow's daughters, maternal
sisters, and paternal sisters.
27
Progress to be expected by using the index by
Legates and Lush (1954) for selections would generally be
about 1.10 to 1.15 times faster than making the selections
on the cow's own performance alone. The exact ratio for a
specific situation would depend on the number of records
on the individual, on the number and kinds of relatives,
and the amount of information on each. Genetic improve-
ment = (G - G) = rIG-z/b-VE where p is the fraction of the
population saved for breeding, g is the height of the ordi-
nate of the normal curve at the point of truncation, g is
the breeding value for fat production and I is the index
or basis for selection.
Harvey and Lush (1952) constructed a selection in-
dex for type and fat production using the same data used
by Legates and Lush (1954). Partial regression coeffi-
cients are given for type and production on a cow and her
daughter with type equal in importance to production and
type one-third as important as production. Partial regres-
sion coefficients are also given for type and production
where production is expressed as the cow's most probable
producing ability.' Regressing a cow's records in this way
would increase the weight applicable to production.
McGilliard (1962) constructed a selection index on
an intra-herd basis using deviations from the herd average
28
of information on the cow, her dam, daughters, maternal
sisters, and paternal sisters. One index was constructed
for fat-corrected milk production and another was con-
structed for type. Each index could be used independently
or combined in a third index which weights the type index
and the production index according to their economic im-
portance and their standard deviations. In this study
McGilliard's production index will be used and type will
not be considered.
Dunbar and Henderson (1954) compared "approximate
indexes" which included five requiring solutions to equa-
tions with varying subsets of data, and in certain in—
stances, with records expressed as deviations from respec-
tive annual averages. Other "approximate indexes" exam—
ined, which required particular tabulations of the data,
were the index described by Legates and Lush (1954), a
modification of their index, estimated and real producing
abilities, the individual's production average, and a rank-
ing by the herd owner.- The ranking of 57 cows indexed by
the application of Henderson's procedure to 452 records on
142 cows accumulated during an 18-year period served as a
basis for comparing certain "approximate indexes." These
comparisons indicate that there is an advantage in combin—
ing the available information such that only a single set
29
of equations need be solved, and also, in the absence of
computing facilities for such a procedure, certain approxi-
mate indexes are accurate enough for practical purposes.
Lorenz (1960) studied a random sample of 5,502
Spotted Mountain cattle of Upper Swabia. The first annual
yield of the daughters was compared with the average yield
of their dams and with the average yield of their dams and
granddams. Theoretically and practically it was concluded
that the data on the yields of the granddams added little
to the accuracy of estimates based on the yields of the
dams; data on the half sibs of the dams were of no impor-
tance.
Mitchell g3 g1. (1960) studied two breeding programs
used by the Ayrshire Association in locating superior or
Approved Dams. The "Original Plan" used production infor-
mation of the daughters and the "Index Plan" used produc-
tion information on daughters, dams, and herd averages.
The results of the study demonstrated that the "Index Plan"
does better than the "Original Plan" in picking out the
genetically superior cows. It was concluded that the in-
dex was twice as effective as the "Original Plan."
Four methods of poultry selection were compared by
Osborne (1957). With low heritability values a selection
index with weights to individual phenotypes and family
50
averages markedly excels selection on lines disregarding
individual phenotypes.
COOper (1962) in a study of the pedigree informa-
tion of A. I. sires indicated that the Equal Parent Index
is a fairly good indicator of how the bull's daughters will
do in an A. I. proof, but is not a good indicator of the
A. I. daughter level. An A. I. proof is usually computed
as the deviation of the average production of all daughters
of a sire from the average production of the contemporaries
of the daughters. The A. I. daughter level is the average
actual production of the daughters of a sire, such as
12,500 pounds of milk and 490 pounds of butterfat.
The study also showed that the bull's A. I. proof
can be predicted from the dam's first record better for
Holsteins than for Jerseys. Indications from this study
are that the dam's average record is a reasonably good in-
dicator of how the bull's A. I. daughters will produce.
The three independent variables: (1) the dam's average
record, (2) the sire's proof, and (5) the paternal grand-
sire's proof accounted for 56 percent of the variation in
the dependent variable. These were all actual records,
and no corrections were made for herds, years, or seasons.
Barr (1962) studied the daughters of 28 Holstein
Friesian bulls as well as the pedigree information of the
51
bulls. There were 19,055 lactations studied. Analysis of
variance of the deviations from regressed adjusted herd-
year-season-stablemate averages were effective in removing
environmental effects within herds. A selection index
using the information on the parents and grandparents was
used to estimate the bull's breeding value. The product-
moment correlation coefficient between the index and the
bull's A. I. proof was .52. The selection index gave about
as much information as eight or nine daughters.
SOURCE OF DATA
The proofs of the bulls used in this study were ob-
tained from the D.H.I.A. Proved Sire List published by the
Agricultural Research Service, U.S.D.A., and the records
of the female relatives of the bulls were obtained from the
Type and Production Year Books of the Holstein—Friesian
Association of America. These were H.I.R. or D.H.I.R.
records. Advanced Registry records were not usable be-
cause all cows in the herd need not be tested in A. R. and,
thus, herd averages were not available.
Sendelbach g3 g1. (1957) used 51 sires with 100 or
more A. I. daughters to study the number of A. I. daugh-
ters necessary to predict a sire's A. I. performance. The
results indicated that 20 to 50 A. 1. daughters are suffi-
cient to estimate future A. I. daughters with reasonable
accuracy. The ability to predict the performance of A. I.
daughters from natural service records was low.
One hundred twenty-six Holstein-Friesian bulls met
the qualifications of having an A. I. Proof with at least
25 daughters and a Natural Proof with at least 5 daughters,
and also pedigree information available on the dam of the
bull. Pedigree information on the dam had to be available
for the bull to qualify, while the bull's maternal granddam,
_ 52 _
53
maternal half sisters of the bull, and maternal and pa-
ternal half sisters of the dam of the bull were also used
when they were available.
The bull's dam's records, the bull's maternal grand-
dam's records, the bull's maternal half-sisters' records,
and the records of the maternal sisters of the dam of the
bull were obtained from the Type and Production Year Books.
Since this study consists of the evaluation of the maternal
side of the bull's pedigree, hereafter the bull's dam will
be referred to as the cow, the bull's maternal granddam as
the dam of the cow, the bull's maternal sisters as the
daughters of the cow, and the maternal and paternal sisters
of the dam of the bull will be referred to as the maternal
and paternal sisters of the cow. There were a total of
654 non-paternal sister relatives of the cow with a total
of 2,890 lactations. For each lactation a herd average
during which that lactation occurred was recorded. If a
cow completed her lactation in a given testing year, the
herd average for that year was used regardless of whether
the cow had started her lactation in the previous testing
year.
The records of the paternal sisters of the dam of
the bull were in the form of contemporary deviations ob-
tained from the proof of the bull's dam's sire. This
information was obtained from the D.H.I.A. Proved Sire
List. There were 5,910 paternal sisters of the bull's
dam.
0f the 126 cows, 79 had dams with records, 105 of
the cows had a total of 258 daughters with records, 78
cows had a total of 171 maternal sisters with records and
76 cows had a total of 5,910 paternal sisters.
Table 4 shows that the cows are the most selected
group and have a larger average deviation from the herd
TABLE 4
Numbers and Averages of Lactations
i
ﬁ
H
No. of No. of Avg. No. Avg. Deviations
Cows Lacts. of Lacts. First All
Cow 126 704 5.65 1,847 1,420
Dam 79 585 4.87 1,452 1,117
Daughters 258 1,045 4.04 1,176 684
Maternal Sibs 171 75s ' 4.43 947 551
Paternal Sibs 5,910 -—- :22: --- 186
Total 6,544 2,890 4.56 1,279 845
average than their relatives.
The maternal sisters of the
cow on the average have more records in a lifetime than
55
the daughters of the cow, however, the daughters' average
deviation is larger than the maternal sisters'. Many of
the daughters of the cow may still be making records.
The distribution of lactations per cow is indicated
in Chart 1. Chart 1 indicates that the cows used in the
study are a select group with 5 of the 654 cows having at
least twelve lactations. Over half of the cows had four
or more lactations and one-third of the cows had six or
more lactations.
Chart l--Distribution of Lactations
No. of
Cows
700-
600
500
400
500
200
I I
o A .
l 2 5 4 5 6 7 8 9 10 11 12
No. of Lactations
METHODS AJD RESULTS
Standardizing the records
A cow's records as published in the Type and Pro-
duction Year Book consist of 90 to 565 days duration if
H.I.R. and 90 to 505 days duration if D.H.I.R. Incomplete
lactations of less than 505 days and the frequency of milk-
ing are indicated.
Herd averages are published annually and from 1956
to the present were calculated as 505—day, 2X, mature
equivalent herd averages. From 1929 to 1955 the herd
averages were merely averages of the actual annual milk
and fat production with the average number of days in milk
and the frequency of milking indicated.
Each lactation was converted to a 5.5 percent fat
corrected milk basis and to a 505-day, 2X, mature equiva-
lent basis. The mature equivalent factors used were those
published in the Holstein-Friesian Type and Production
Year Book (1959). Yearly herd averages which were not
505-day, 2X, mature equivalent herd averages; i.e., 1929
thru 1955 were extended to a 505-day basis by the extension
factors published in the Holstein-Friesian Type and Produc-
tion Year Book (1959) and multiplied by a factor of 1.10
to be considered 505-day, 2X, mature equivalent herd aver-
ages. According to the D.H.I.A. Proved Sire List, the
- 56 _
57
factor used by the U.S.D.A. is 1.09. Herd averages which
were 5X were converted to 505 days and considered as 505-
day, 2X, mature equivalent herd averages.
Herd to herd differences which are estimated to be
80 to 90 percent environmental and 10 to 20 percent gene-
tic (Lush and McGilliard, 1955; Robertson et al., 1961;
Robertson and Rendel, 1954; and Firchner, 1959) were re-
moved by deviating every 505-day, 2X, mature equivalent
record from the corresponding 505-day, 2X, mature equivalent
herd average.
Indexing he bulls
Selection indexes for dairy cattle by Tabler and
Touchberry (1955, 1959), Legates and Lush (1954), Harvey
and Lush (1952), Eldridge and Salisbury (1949), Barr (1962)
and McGilliard (1962) have been discussed earlier. The
selection index used in this study (McGilliard, 1962) was
constructed on an intra—herd basis using all records as
deviations from the herd average. The herd average here-
after will be considered as the average 505-day, 2X, mature
equivalent production of all the cows during the testing
year of the herd. The cows, dams, daughters, maternal
sisters, and paternal sisters records are eXpressed as fat-
corrected milk. The paternal sisters are weighted inde-
pendently of the other combinations of relatives present
\N
C0
and are additive while the wei;hts for the other relatives
are dependent upon the number of individuals in each group
and the combinations present. Figure 1 shows the rela-
tionships between the groups of relatives used in the in-
dex. The symbols used in Figure l are:
G--genic value for milk production of the individual
in question.
P-—phenotypic value of the individual in question
(reference may be to the average of all records
or the first record of the individual).
til
--the combined effects of environment, dominance,
and epistasis.
AlG--genotype of the first offspring of the young
sire.
AlP--phenotype of the first offspring of the young
sire.
_L-represents the average of the class involved (KP
is the average production per lactation of the
daughters of the young sire).
B-—the young sire.
S--the sire of the young sire.
C—-cow, the dam of the young sire.
D--dam of the cow.
CS--cow's sire.
c--environmental correlatien between half sibs.
59
Figure l--Path Diagram Indicating the Theoretical Correla-
tions Between the Phenotypes and Genotypes of
the Young Sire and Its Close Relatives
40
h--square root of heritability or the correlation
between the genotype and phenotype.
.5--represents Mendelian segregation if no intense
inbreeding is present. Under all conditions
Mendelian segregation is represented by(l/2)
‘Vl.+ f'/l + f where f' and f are the inbreed-
ing coefficients of the parent and offspring
respectively. It is assumed here that f'
equals f or Mendelian segregation is equal
to .5.
All of the cow's records are averaged to produce an
average deviation. The daughters and maternal sisters
average deviations are averaged to form one overall average
deviation for the respective classes. The apprOpriate
weights are applied to each of the five classes of rela-
tives to produce an index or estimate of the cow's genetic
ability. For example: a cow averages 1,000 pounds of milk
above the herd average, her dam is 500 pounds of milk below
herd average, three daughters average 400 pounds of milk
above herd average and four maternal sisters average 100
pounds of milk above herd average. Sixty paternal sisters
average 90 pounds of milk above herd average. The weights
for this combination are found in Table 5.
The cow's index would be 276. The standard devia-
tion of the index is approximately 720 pounds of milk, and
41
it has an expected mean of zero with a random sample of
cows.
TABLE 5
Index Weights for a Cow with 5 Daughters,
4 Maternal Sisters and 60 Paternal Sistersa
Cows Dams Daus. M. . P.S.
Wt. Wt. No. at. No. ﬁt. ho. wt.
.18 .14 5 .29 5 .08 52 .45
.18 .14 5 .29 4 .10 59 .44
.18 .14 5 .29 5 .12 69 .45
aMcGilliard, 1962.
The index of 126 dams of the A. I. bulls was calcu-
lated using all records and first records to see the value
of each. The respective indexes were correlated with the
A. 1. Proof, daughter-dam comparison and the natural proof
expressed as deviations from contemporary herd mates.
The proofs ranged in numbers of daughters from 25
to 1,526 for the A. I. Proof and the daughter-dam compari-
son and natural proof ranged from 5 to 120 daughters. To
correct for unequal numbers, the A. I. Proofs were re-
gressed with the factor N/(N + 12) and the non-A. I.
Proofs were regressed by the factor N/(N + 16).
42
The correlations between the two indexes on the
dam and the three proofs on her son are given in Table 6.
The index on first records seems to be of as much value as
the index on all records, as correlated with the A. 1.
Proof. The A. I. Proof and the natural proof as devi-
ations from contemporaries correlate quite.closely with
the two indexes, while the daughter-dam comparison seems
to be of little value since it correlates -.085 using first
records index and -.019 using the index with all records.
TABLE 6
Correlations, Means and Standard Deviations
of Indexes and Proofs
Index Index A. I. D.—D. Nat. Pr.
Index (lst. Recs.) .148 -.085 .155
Index (111 Recs.)_ .149 -.019 .092
A. I. Proof .299 .552
Dau.-Dam Comp. .265
Means ‘ 852 599 55 217 141
Std. Dev. 822 725 545 577 629
Components of variance
The accuracy of the index depends upon the proper
weights being applied to each of the records of the
45
relatives. A variance-covariance matrix using first re-
cords and one using all records ;vas computed by using the
average deviation of each animal and the average of the
daughters' and maternal sisters' average deviation. If
more than one daughter, one maternal sister, or one pater-
nal sister were available, they were averaged to produce
an average deviation for the daughter class, maternal sis-
ter class, and paternal sister class. The five groups of
relatives, using first records and all records, were cor-
related with the bull's adjusted A. I. Proof. The A. I.
Proof was adjusted for the numbers of daughters present
by using the regression N/(N + 12) where E is the number
of daughters in the proof.
The product moment correlations in Tables 7 and 8
demonstrate the phenotypic relationships observed between
the five groups of relatives used in the selection index.
With no environmental variation these would be expected
to be equal or greater than zero, but not negative. The
product moment correlations between the A. I. Proof of
the bull and the five groups of female relatives (Tables 7
and 8) demonstrate the observed relationship between the
genotype of the bull and the phenotypes of the five groups
of female relatives. The variances of the five groups of
relatives and the A. 1. Proof of the bull are located on
44
Variances, Covariances, and Correlations
Using All Records
Cow Dam Daus. M. S. P. S. A.I. Proof
Cow 41,745 5,556 4,064 11,718 1,709 11,146
Dam .159 49,827 -514 6,197 877 -10,058
Daus. .120 -.004 26,819 —l,055 2,569 25,822
M. S. .555 .186 -.056 54,058 2,278 6,505
P. S. .067 .059 .099 .105 14,067 -842
A. I. Pr. .101 -.081 .257 .068 -.012 294,525
(Data expressed in 10 pounds)
TABLE 8
Variances, Covariances, and Correlations
Using First Records
Cow Dam Daus. M. S. P. S. A.I. Proof
Cow 61,520 55 -l,922 12,285 2,269 24,581
Dam .001 58,514 -2,824 8,882 -925 -20,451
Daus. -.058 -.061 59,170 2,857 6,514 14,704
M. S. .275 .258 .076 58,447 —591 12,994
P. S. .086 -.057 .222 -.025 14,067 —842
A. I. Pr. .181 —.152 .152 .128 -.012 294,525
(Data expressed in 10 pounds)
45
the diagonal of Tables 7 and 8. The variance of the
daughter, maternal sister, and paternal sister groups is
the variance of the average of E cows in each group. In
this data 3 ranges from 1 to 999 cows. The variance of a
single cow in the daughter, maternal sister, and paternal
sister groups was obtained by components of variance
(Tables 9 and 10) and was 55,017 for first records and
40,945 for all records.
TABLE 9
Components of Variance--First Records
Corrected Sums of Squares u d2 e2 S. S.
Total 0 550.6951 553 54,467,957
Between 0 550.6951 229 17,290,505
Residual 0 0 524 17,177,654
Components
e2 = 55,017
h2 = .599 d2 = 9,551
The product moment correlations between the rela-
tives and the bull's A. 1. Proof (Tables 7 and 8) indicate
that the selection index does not evaluate the data ade-
quately. The cow's phenotype alone, using first records
46
as deviations from the herd average, is a better indicator
of the bull's A. 1. Proof than the selection index, with a
correlation of .181 (Table 8) compared to the correlation
of .148 (Table 6) between the selection index and the A. I.
Proof. The cow's daughters, using all records as devi-
ations from the herd average, are much more accurate than
the selection index with a correlation of .257 (Table 7)
as compared to the correlation between the selection index
and the A. I. Proof of .149 (Table 6).
TABLE 10
Components of Variance--All Records
Corrected Sums of Squares
u d2 62 S. S.
Total 0 550.6951 555 26,069,548
Between 0 550.6951 229 12,805,524
Residual O 0 524 15,266,024
Components
e2 = 40,945
h2 = .528 d2 = 6,223
Components of variance using daughters within dams
was used to estimate the variance of a single daughter, a
single maternal sister and a single paternal sister. The
47
components of variance were estimated from daughters
within dams which also included the cow and her maternal
sisters within the dam. Each dam had an average of ap-
proximately 5.5 daughters and there were 250 dams with
daughters in the analysis. As would be expected, the
variance of the first records was larger than the variance
of the average of all records as shown in Tables 9 and 10.
This also yielded the intra-class correlation which esti-
mated the heritability of first records as .599 and the
heritability of all records as .528. Other estimates of
heritability are much lower and indicate that the herita-
bility of first records to be higher than that of all
records as shown in Table 11. The paternal sister corre-
lation was computed as four times the correlation between
TABLE 11
Heritability Estimates
Method of estimation First Records All Records
Intra-class correlation .599 .528
Paternal sister correlation .171 .167
Daughter-dam regression .079 .510
the cow and her paternal sisters. The daughter-dam regres—
sion was calculated as two times the regression of daughters
48
on cows, which also included combining the cow and her
maternal sisters and regressing them on the dam.
The cows which indexed above two standard devi-
ations using all records had sons which had an average A.
I. Proof of +500 pounds of milk above an expected mean of
zero and the standard deviation of the A. I. Proof was
545 pounds of milk. The top bull had a dam which indexed
-277 and would not have been included in a young sire pro-
gram. Three of the t0p ten bulls would have been chosen
for a young sire program.
With the index using first records, the nineteen
cows which indexed above two standard deviations of milk
would have yielded four of the top ten bulls for a young
sire program. The nineteen dams which were two or more
standard deviations above the mean yielded sons with a
mean A. I. Proof of +175 pounds of milk where a standard
deviation of the A. I. Proof is 545 pOunds of milk. Table
12 compares the two methods of selection, first records
and all records, and shows an advantage to using all
records.
Indexes Above Two Standard Deviations
And the Son's A.
TABLE 12
I.
Proof
49
All Records
Cow's Index SonTs Proof
First Records
Cow's Index Son‘s Proof
\O (I)\‘IO\\J1 -P'\Nl\)l—‘
FHA
FWD
0
12:
15.
14.
15.
l6.
17.
18.
19.
2,998
2,546
2,466
2,454
1.985
1,924
1,807
1.799
1,670
1,639
1,588
1.569
1,499
862
180
722
52
-45
1,194
—40
451
-425
1,245
-245
560
-11
4,541
2,671
2,665
2,500
2,254
2,216
2,192
2,185
2.159
2,101
2,096
2,065
2,065
2,051
1,892
1,890
1,817
1,768
1,698
862
1,017
.40
180
772
-1,072
-11
52
-417
548
~158
-265
451
1,245
427
-245
1,194
-425
-77l
DISCUSSION
There are two types of selection indexes published
for selection of dairy cattle, namely, those for the selec-
tion on type and production and those for the selection on
milk and/or fat production. 0f the indexes which deal with
production, McGilliard's (1962) best met the purposes of
this study. The index was designed to be applied to cows
with information on themselves, and any other additional
information on her close female relatives is also used.
The index of Legates and Lush (1954) was constructed
from Jersey data for fat production. In this index the
five categories of relatives are combined additively and
independently, thus indicating the members of the pedigree
to be somewhat independent and the correlations between
them to be small. The correlation between the index value
and the individual's genotype may be smaller by combining
the relatives additively and independently than if the
correlations between the categories are used and the weights
are dependent upon the information available in all cate-
gories. McGilliard's (1962) selection index combines the
paternal sisters additively and independently of the other
sources of information. The weights for the cow, her dam,
daughters, and maternal sisters are all dependent upon the
numbers and the amount of information in all the categories.
- 5Q -
51
Barr (1962) published an index on young sires utili-
zing the information on the sire's and dam's side of the
pedigree. Three elements on the sire's side and four on
the dam's side of the pedigree were combined in a correla-
tion matrix and the solutions for a given sire may be at-
tained. This is good for living animals, but for the se—
lection of dams to be bred for future young sires, the
index by McGilliard (1962) is advantageous.
The A. I. Proofs of the sires were adjusted for
unequal numbers of daughters by using the regression
N/(N + 12) which was used by Henderson and found by Specht
(1957) to be the correct regression for Michigan data.
This regression assumes no environmental correlations be-
tween paternal half sisters. The correlation between single
paternal sisters in this data was .062 which yields a re-
gression of N/(N + 15). This is in close agreement with
the regression factor used on the natural proofs, i.e.,
N/(N + 16), which are assumed to be larger than that used
on A. I. Proofs.
The correlations between the natural proofs and the
A. I. Proofs in this study were low and in the order of
.50. The dam's index correlates lowest with the daughter-
dam comparison, intermediate with the Natural Proof ex-
pressed as a contemporary comparison and highest with the
A. 1. Proof. The dam's index correlated .149 with the
52
A. I. Proof or approximately one half the correlation be-
tween either natural proof and the A. I. Proof.
If the sire of a bull were an artificially proven
sire, his proof may be a much better indicator of his
genetic ability than a selection index is of a cow's gene-
tic ability. Thus, the sire's side of the pedigree may be
of more value than the dam's in estimating a bull's gene-
tic ability. when consideration is given to the sire's
and dam's side of the pedigree, it would appear that a
complete pedigree on a young sire may yield information ap-
proximately equal to that obtained from a natural proof.
Barr (1962) found a correlation of .52 between a complete
pedigree of a sire evaluated by an index and the sire's
A. 1. Proof. The pedigree would be available before the
natural proof and even before the bull is of service age.
It may be cheaper and may indicate the genetic potential
as well as a natural proof. Early selection on the basis
of such an index would seem to be the most economical and
practical way of selecting sires in the future.
When the first records of the cow and her relatives
were put in the selection index, it correlated with the
A. I. Proof, .148 which is slightly less than .149, the
correlation obtained by using all records. The advantage
of using first records is that an estimate of an
55
individual's ability is obtained in the first lactation
and less environmental variations effect first records.
Johansson (1955) analyzed 4,912 daughter-dam pairs with
first, second, and third lactations and the results show
that the first lactation record is significantly superior
to the second and slightly superior to the third lactation
as an indicator of the cow's inherent capacity for milk
yield. Putman g3 g1. (1945) from the results of 5,588
TABLE 15
Heritabilities of Lactation Recordsa
Lactation Number Heritability
1 .55 i .06
2 .10 i .05
5 .24 i .04
aJohansson, 1955.
dam-daughter pairs found the correlation between first
records and the average of all records to range from .874
to .951, and concluded that there were insignificant dif-
ferences between using first records and all records.
Rennie and Bremner (1961) studied Jersey data in
Canada to determine the validity of selection of sires on
54
the basis of only first lactation data and the bias that
this may introduce. The data indicated that sire programs
based on records of two-year-old cows appear to identify
properly those sires of superior breeding value for pro-
duction at all ages. 0n the average, high production
during the first lactation is followed by a high level of
production in subsequent lactations.
The heritability of deviations of first lactations
and all lactations from herd averages would appear to be
higher than the heritability of undeviated production
records since some of the environmental variance is elimi-
nated by deviating records from the herd averages. If
heritability exceeds .40, then the correlation between an
individual's phenotype and genotype will exceed .65 and
it will require a large number of relatives to be of much
value in obtaining a better estimate of the individual's
genotype. For practical purposes, if the true heritabili-
ties were as indicated by the components of variance, it
would be of little value to pay attention to anything other
than the individual's own phenotype. The heritability esti-
mates obtained by the components of variance seem to be
biased since the daughters and dam tend to be in the same
herd and may have environmental correlations. Selection
indexes or the added information of relatives is of
55
greatest value where heritability is less than .40 and as
it approaches zero.
The bulls in this study came from herds which had
herd averages which ranged from 9,000 pounds of milk to
18,000 pounds of milk. If 10 to 20 percent of this differ-
ence between the high and low herds is genetic, then the
cows indexed in herds with high herd averages would be
penalized to the extent of this difference, since all re-
cords were deviated from the herd averages and then as-
sumed on an equal genetic basis. In this study the standard
deviation of deviations from herd averages is assumed equal
in herds with high and low herd averages. If the standard
deviation is greater in herds with high herd averages, then
cows indexed from high herds may be biased downward due to
the genetic differences between the herd averages and
biased upward due to a larger standard deviation of the
index. The combined effect of both biases is undetermined.
This may be especially true of data of the type used in
this study because of the large number of bulls in studs
which are from herds with high herd averages.
The amount of preferential treatment given animals
in the pedigrees of bulls in artificial breeding studs is
difficult to determine and there is no way to correct for
it. It would seem that such bias does occur and would be
more likely to occur in the records of the dam of the bull.
56
With large numbers of daughters, maternal sisters, and
paternal sisters, this bias could be reduced a little. The
use of first records would tend to reduce the amount of
bias due to preferential treatment since the first lacta-
tions usually would have occurred before a son was avail-
able or of known superior quality to qualify for A. I. ser-
vice. Usually the only preferential treatment that may
occur with first records is that to half sisters of the
bull or daughters of the dam of the bull.
Due to small numbers there may be large sampling
errors in the calculated covariances in Tables 7 and 8.
The covariance with the largest numbers was 126 and the
covariance with the smallest numbers was 54. The covari-
ances in these matrices indicate the possible causes of
discrepencies between the actual data and the selection
index by McGilliard (1962). Theoretically, none of the
covariances should have been negative, instead those
between the paternal sisters and the maternal sisters and
the covariance between the paternal sisters and the dam
should have been zero and the rest should have been posi-
tive. The sign of the covariances between the A. I. Proof
and the female relatives of the bulls determines whether
the weight for the category will be positive or negative.
Using all records and first records, it can be seen that
the prOper weights for the dam and paternal sisters should
57
have been negative. The covariance between the paternal
sisters and the A. I. Proof is essentially zero and could
be attributed to sampling errors. However, the covariance
between the dam and the A. I. Proof is a very large nega-
tive and although some of it may be attributed to sampling
error, it seems that the covariance would still remain
negative giving the dam a negative weight.
The covariances in the matrices of first and all
records give an indication of the environmental correla-
tions present. The most evident ones are the ones between
the maternal half sisters which seem to inflate the pheno-
typic correlations. The average of the maternal sisters
correlated more closely with the dam than the cow corre-
lated with the dam. The paternal sisters are not neces-
sarily in the same herd with the other relatives. The
magnitude of the paternal sister's covariances, which
tend to be less biased with environmental correlations
along with their relationship with the various relatives,
appear to show the magnitude of the true covariances with
most of the environmental correlations eliminated.
The superiority of using first records or all
records cannot be demonstrated from these data due to the
small numbers.
Artificial breeding organizations with adequate size
and an adequate number of first services to sample enough
58
young sires so as to make the maximum genetic gain are few.
Due to the cost of such a prOgram, it seems to be a prac-
tical and reasonable method to sample about 5 to 10 sires
a year in an average size artificial breeding stud. The
data from this study indicate that the selection of su-
perior cows by the use of a selection index and the select
mating of these dams to superior A. I. Proved sires may
yield superior offspring. The tOp few indexed cows in a
state or given area could also be judged as to physical
appearance or type before the artificial breeding organi-
zation bred the cow and contracted for a bull calf for the
young sire program.
An artificial breeding organization may not want
to contract a first or second calf heifer pending her fu-
ture production or a better estimate of her ability. This
should not reduce the selection intensity which is avail—
able to such a breeding organization, due to the large
numbers available. The cost of the calves would be less
than naturally proven sires and a longer service life
would be available. The young sire's pedigree may afford
as much information as a natural proof in predicting his
A. I. daughter production and the selection differential
would be considerably higher on the young sires than it
would on bulls with a natural proof.
SUKHARY
To study the value of selection indexes in a Young
Sire Program, 126 artificially proven sires which met the
qualifications of having at least 25 artificial daughters,
5 natural daughters, and pedigree information on the dam
of the bull and her relatives were used. The dam‘s side
of the pedigree was completely analyzed by compiling all
the available production records on (1) the bull's dam,
(2) the dam's dam, (5) the dam's daughters, (4) the dam's
maternal sisters, and (5) the dam's paternal sisters. All
records were converted to a BOB-day, 2X, mature equivalent
basis and were deviated from the 505-day, 2X, mature equi-
valent herd average.
The 126 cows (dams of the bulls) had 704 lactations
which averaged 1,420 pounds of milk above herd average for
all records and 1,847 pounds above herd average for first
records. There were 79 dams with 385 lactations which
averaged 1,452 pounds of milk above herd average for
first records and 1,117 pounds of milk above herd average
for all records. The 258 daughters had 1,045 lactations
which had an average deviation of 684 pounds of milk for
all records and 1,176 pounds of milk for first records.
The 171 maternal sisters had 758 lactations with an aver-
age deviation of 551 pounds of milk for all records and
-59-
60
947 pounds above herd average with first records. There
were 5,910 paternal sisters which averaged 186 pounds
above the herd average.
The A. I. Proofs ranged in numbers of daughters
from 25 to 1,526 and from 5 to 120 daughters for the
Daughter-Dam Comparison and the Natural Proof. To correct
for unequal numbers, the A. I. Proofs were regressed with
the factor N/(N + 12) and the two non-A. I. Proofs were
regressed by the factor N/(N + 16).
The dams of the bulls were indexed using first
records and the average of all records by McGilliard's
(1962) selection index. The index using first records cor-
related with the A. I. Proof +.l48 and the index using all
records correlated with the A. I. Proof +.l49. The dam's
index correlated approximately one half as much as the
correlation between the A. I. Proof and either non- A. I.
Proof.
If the sire's side of the pedigree would yield as
much information as the dam's side, a complete pedigree
with information on the dam and a sire which has an A. I.
Proof may yield as much information on a young sire as a
Natural Proof could yield.
The advantages of a young sire program are: (1)
high selection intensity, (2) lower initial cost per sire,
61
(5) an earlier A. I. Proof on the sire, and (4) a longer
A. I. service life.
The most practical and economical way of obtaining
future superior sires is by the use of young sires. All
the cows in a state or a given area could be indexed and
the cows with the best indexes could be contracted and
bred to a superior proven sire for the purpose of obtain-
ing young sires.
LITERATURE CITE
Barr, G. R. 1962. Selecting young dairy sires on differ-
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Berry, J. C. 1952. Evaluating dairy sires. Jour. Dairy
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Carter, H. Wilmot. 1961. Accuracy of evaluating A. I.
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COOper, Tommye. 1962. Comparison of original pedigree
information with artificial breeding proofs of sires
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M. S. Thesis, University of Kentucky, Lexington, Ky.
Copeland, Lynn. 1951. The contribution of the dam in in-
heritance of milk and butterfat. Jour. Dairy Sci.,
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Copeland, Lynn. 1954. Pedigree analysis as a basis of
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Dickey, H. C. and Labarthe, P. 1945. Predicting the
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Dunbar, R. S. and Henderson, C. R. 1954. A comparison of
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- 62 -
65
Harvey, W. H. and Lush, J. L. 1952. Genetic correlation
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64
Lush, J. L. 1947. Family merit and individual merit as
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Genetic improvement in production attributable to
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1960. Distribution and parameters of records of
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