Influence of Heredity and Environment on
Weaning and Post-Weaning Weights
in Beef Cattle
JAMES HORACE MEADE, JR.
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
AC 'i ,I DGMEITS
The author wishes to express his sincere appreciation to
Dr. ,Marvin Koger, chairman of his supervisory committee, for his
guidance and assistance throughout this study and in the preparation
of this dissertation.
Appreciation is also expressed to Dr. A. C. Warnick, Dr. T. J.
Cunha, Dr. J. R. Edwardson and Dr. A. E. Brandt for their supervision
Special thanks are expressed to Ir. R. W. Kidder and the other
personnel at the Everglades Experiment Station who collected the data
used in this study and made it available for analysis.
Appreciation is expressed to D. D. Ilargrove and R. E. Deese
for reading the rough manuscript.
The author wishes to give special thanks to his wife PIarion iell
for her encouragement and help throughout his graduate career.
TABLE OF CONTENTS
ACi'iOWLZ; DGMI- ilTS . . ii
LIST OF TABLES ............... iv
INTRODUCTION . .... .. 1
REVIEW OF LITERATUIE . .... .. 3
Weaning Performance . . 3
Post-Weaning Performance . .. 11
MATERIALS AND METHODS ................... 13
FLJ7LLT . ... . .20
205-Day Weight . . ... .. 20
12- and 18-Month Weight . ... 29
DI.-CU.. lcri . . . 35
SU MARY . . ... .. 42
APPENDIX. .......................... 44
LITERATURE CITED .. . .... 55
LIST OF TABLES
1. Variance Analysis for Main Effects Influencing
205-Day WJeights . . 21
2. Approximate "en '.uares for First-Order Interactions 22
3. Least Squares Effects by Year . .... 23
4. Least Squares Effects by Breed . ... 25
5. Least Squares Effects by Sex and Age of Dam .. 27
6. Least -quares Effects by Lactation St tus -nd Month of
Birth . . ... .. .. 28
7. Variance An--lysis for '-MIonth Weight ... 30
8. Variance Analysis for 18-M!onth Weight ... 30
9. Interaction of Year with Breed . .... 31
10. Least Scuares Effects of Year of Birth on 12- '%nd 18-
Month Weights . . .... 31
11. Least Scwures Effects of Breed on 1 and l -Month
Weights . . ... .. .. 32
12. Partial regression Coefficients for Regression of
Weight on Age at Weaning . 34
13. Multiple Correlation Coefficients with Certain Classi-
fications Omitted from Nodel . .... 36
14. Original Least Squares Equ'ations . .. 45
15. Inverse of Reduced Coefficient Matrix ... 49
16. Cows Bred and Calves Weaned by Year and Breed Group 53
IiT. '-'L i' ACTION
Inherent biological factors create much variability in measure-
ments taken to evaluate beef cattle performance. Some of this
variability can be attributed to genetic differences between animals,
some to environmental influences and some to genetic-environmental
interactions. In order to accurately evaluate beef cattle performance,
estimates of the various factors which influence performance are
necessary. A thorough knowledge of these factors should enable the
livestock breeder to develop more accurate breeding and selection
During recent years there have been many papers published con-
cerning the performance of different populations of beef cattle.
However, due to environmental differences and genetic-environmental
interactions, the livestock producer must have valid estimates of the
factors influencing performance in the specific population which con-
cerns him. This is particularly true in Florida because the environ-
mental conditions are quite different from those prevailing throughout
most of the United States. Therefore, the ability of an animal to
adapt to his environment takes on added significance. Consequently,
accurate estimates of the factors which influence beef cattle perform-
ance under Florida conditions should be of value to Florida cattlemen.
This study was undertaken with the purpose of obtaining estimates
of genetic and environmental influences on weaning and post-weaning
gains of beef cattle under south Florida conditions. The specific
population involved was that of the Everglades Experiment Station beef
cattle herd. This population contained Angus, Brahman, Devon, Brahman-
Angus and Brahman-Devon cattle. Weaning weights were available for all
calves. Also, since very little culling was practiced, 12- and 18-month
weights were available for practically all heifers.
REVL-W OF LITERATURE
Effect of Year
Numerous investigations have shown that the effects of year
cause the weaning weights of calves to fluctuate widely. Burgess,
Landblom and Stonaker (1954) reported the effects of year on the
weaning weight of Hereford calves. They obtained a range in year
effects of 44 pounds for a six-year period. Similar year effects
were found by Godbey et ,al. (1959), Brown (1960) and Godley et al.
(1960). In a study of the Everglades Experiment Station beef cattle
herd from 1931 to 1955, Clum (1956) obtained a range in year effects
of over 100 pounds. Brown (1958) also obtained a range in year effects
of over 100 pounds. Reynolds (1960) analyzed the records of the Range
Cattle Experiment Station, Ona, Florida, for a 15-year period. He
found that the range in year effects was 85 pounds.
Effect of Sex
The fact that sex has an effect on the weaning weights of calves
has been known for some time. Koger and Knox (194)), using data col-
lected over an eight-year period on 863 Hereford calves, determined the
mean weaning weights of male and female calves corrected for differences
in weaning age. The average weaning weight was 443 pounds for 419 steers
and 411 pounds for 444 heifers. The steers were heavier than the
heifers each year. However, Gregory, Blunn and Baker (1950) found
little difference in weaning weight between male and female calves.
Botkin and Whatley (1953) analyzed the weaning weights of 701 calves
produced by range Hereford cows and reported that the males averaged
25 pounds heavier than the females. In a review of the influence of sex
of calf on weaning weight, fmith and Warwick (1953) determined that male
calves averaged 23 to 49 pounds heavier than females. Bull calves were
22 pounds heavier and steer calves 2 pounds heavier than heifers at
weaning in a study by Burgess, Landblom and L'tonaker (1954). Rollins
and Guilbert (1954) observed that bull calves were 68 pounds heavier
than heifer calves at 240 days of age.
A study conducted by Koch and Clark (1955) showed that male
calves averaged 26 pounds heavier at weaning than female calves. Clum
(1956) noted that male calves averaged 25 pounds heavier at 180 days
of age than females. Marlowe and Gaines (1958) averaged the records
of 4166 calves in the Virginia performance testing program. The data
were pooled over all years and over 44 Angus, 19 Hereford and 3 Short-
horn herds located in the state. At 210 days of age steers were 30
pounds heavier than heifers. Similar estimates were obtained by Koch
(1951), Brown (1960), Reynolds (1960) and Meade, lHrmmond and Koger
(1961). A difference of 41 pounds in favor of steer calves was reported
by Godbey et al. (1959) and Godley et al. (1960).
Effect of Age of D:un
The age of the dam at calving has been shown to influence the
weaning weights of calves to a certain extent. Knapp, Baker, Quesen-
berry and Clark (1942) observed that maximum weaning weights of calves
may be expected from six-year-old cows with a gradual increase from two
to six years and a more rapid decrease from six to 11 ye-r,. Knox and
Koger (1945) showed that the age of maximum production of range cows
was from six to eight years with the peak at seven years. Sawyer,
Bogart and Oloufa (1949) noted that two-year-old cows weaned calves
75 pounds lighter than mature cows. The weaning weight of calves in-
creased with increasing age of darmi through eight years but then
declined. Botkin and Whatley (1953) considered all cows five years
old and older as mature. We ning weights were adjusted to a mature
cow equivalent by adding 35 and 15 pounds to the weights of cloves
from three- and four-year-old cows, respectively.
In a review of the influence of age of dam on calf weights,
Smith and Warwick (1953) found that maximum weaning weights were
usually obtained from dams six to nine years of age. Lurgess, Landblom
and Stonaker (1954) developed a series of constants to increase effec-
tiveness of selection for weaning weights. They adjusted for age of
dam by adding 15 pounds to calves from two-year-old cows, 10 pounds to
calves from cows nine years and over, and subtracting 5 pounds from calves
weaned by cows three to five years of age and 21 pounds from calves
weaned by cows six to eight years of age. Koch and Clark (1955) used
a number of correction factors to correct for the effect of age of dam
on weaning weight. They corrected by adding to the weaning weights of
calves produced by: 3-year-old dams, 46 pounds; 4-year-old, 21 pounds;
5-year-old, 8 pounds; 6-year-old, 0 pounds; 7-year-old, 2 pounds;
8-year-old, 4 pounds; 9 year-old, 7 pounds; and 10-year-old, 14 pounds.
McCormick and others (1956) determined that age of dam exerted a
significant influence on 210-day weights of calves. Calves produced
by two-year-old cows were 107 pounds lighter than those produced by
eight-year-old cows. Calves from three-year-old dams were 63 to 73
pounds lighter than those from mature dams. Weaning weights of the
calves produced gradually increased with age of dam until the cows
reached maturity at seven or eight years of age.
Clum (1956) adjusted calf weights to a mature dam equivalent by
adding 35, 12, 5, 3, 8, 18, 34, 53 and 53 pounds to calves from cows
aged 2, 3, 4, 11, 12, 13, 14, 15 and 16 years, respectively. Marlowe
and Gaines (1958) reported that maximum production was obtained from
six- to eight-year-old cows. They made adjustments for age of dam on
calves from cows that were 2, 3, 4, 5 and over 10 years of age at
date of calving. Results similar to these were obtained by Brown
(1958), Clark et al. (195&), Reynolds (1960) and Meade, Hammond and
Effect of Month of Birth
Clum (1956) reported that within year variability due to month
of birth influenced the 180-day weights of calves. He found that
calves born in the months of December thLbou,_h May were heavier than
calves born from July through November. Peacock, Kirk and Koger (1956)
stated that calves born during December, January and February were
14 pounds heavier at 180 days of age than calves born during Larch,
April and May. Koger (1958) indicated that December and January
calves were heavier than February, IMarch or April calves. Results of
a study by Marlowe, Kincaid and Litton (1958) gove evidence that sea-
son of birth contributed to the variability in preweaning gain. Brown
(1958) reported that calves born during February, Larch -nd April were
heavier than calves born from September through January. Reynolds
(1960) found that the weaning weights of c-lves born from January
through April were heavier by 7 pounds than calves born in December
or May, and were 15 pounds heavier than those born from June through
November. Marlowe and Gaines (1958) and Brown (1960) have also shown
that season of birth influences the weaning weights of calves.
Effect of Lactation Status
Reynolds (1960) found that lactation status of the dam during
the breeding season exerted a significant influence on weaning weight.
He obtained an interaction of lactation status with pasture, year and
breed. However, Mieade, Hanmmond and Koger (1961) reported that lacta-
tion status of the dam did not influence weaning weight in a purebred
Effect of Breed
Numerous investigations have shown that under specific environ-
mental conditions breed of calf exerts a significant influence on
weaning weight. Bray (1933) reported that half-Brahman calves were
heavier at weaning than either Hereford or Angus calves. In 1934,
Black, Semple and Lush reported the results of mating Brahman bulls
to Shorthorn and Hereford cows. At weaning, the steers containing
Brahman blood were heavier than the non-Brahman steers. Phillips and
others (1942) found that Shorthorn-Hereford steers out of Hereford
cows were slightly heavier at weaning than purebred Hereford steers.
For the Gulf Coast area, Rhoad and Black (1943) recommended Brahman
hybrid beef-type bulls for use on range cows with one-half to three-
fourths the blood of a pure beef breed. They stated that one parent
of the hybrid bulls should be of the same pure beef breed that sired
the range cows and the other parent predominately of Brahman breeding
and of acceptable beef-type conformation.
In a study by Rhoad, Phillips and Dawson (1945), calves from
Angus dams when mated to Angus bulls were lighter at six months of
age than when mated to Africander or Zebu bulls. Baker and Black
(1950) found that average weight at six months of age was significantly
greater for calves out of Brahman-Angus cows than for calves out of
purebred Angus cows, irrespective of sire. In a review, Warwick (1950)
reported that Brahman crossbred calves were 35 pounds heavier at wean-
ing than British type calves. Calves from Brahman crossbred dams
were 81 pounds heavier at weaning than calves from British type cows.
Gerlaugh, Kunkle and Rife (1951) made reciprocal crosses with Angus
and Hereford cattle. The crossbred calves had only a slight advantage
in weight at weaning over the purebreds.
Kidder and Chapman (1952) gave a preliminary report of weight
performance of crossbred and purebred cattle at the Everglades Experi-
ment Station. Their results indicated that progeny of reciprocal
crosses of Brahman X Angus and Brahman X Devon were superior in weight
gains to either of the purebred lines of the respective cross.
The results from 22 published experiments in crossbreeding
beef cattle were appraised by Holt (1955). These included British
breeds, other European breeds, Zebus and unimproved cattle. Crossbred
calves averaged 3.5 per cent above the parental average in weaning
weight. McCormick and Southwell (1955) summarized the weaning per-
formance of British and British-Brahman F1 calves. The British calves
were 30 pounds lighter at weaning.
Kidder, Liddon, Clum and I:o,rer (1956) analyzed the growth re-
sponse of Angus, Brahman and Devon cattle and various crosses of these
breeds. A marked heterosis effect on growth to 180 days resulted from
the various Brahman-Devon crosses. Calves from crossbred dams by
crossbred sires were lighter than F1 calves or calves from crossbred
dams by purebred sires. They stated that in the Angus-Brahman groups,
heterosis effects were marked in both growth rate of calves and mother-
ing ability of dams.
McComas, Cook and Dawson (1956) found that F1 Red Dane X Red
Poll heifers made more rapid gains from birth to weaning than did Hed
Poll heifers. Peacock, Kirk and Koger (1956) obtained a significant
difference between weaning weights of calves mothered by dams of dif-
ferent breeding. Cows with one-half Brahman breeding weaned the
heaviest calves and cows containing no Brahman breeding weaned the
lightest calves. Weaning weights of calves from cows with 1/32 to
15/32 and 17/32 to 31/32 Brahman breeding were intermediate.
McCormick and Southwell (1957) stated that c:ives from Brahm an bulls
mated to Hereford cows were 27 pounds heavier at weaning than calves
from Angus bulls mated to Hereford cows. Using a rotational cross-
breeding system with iAngu, Hereford and Shorthorn cattle, Quesen-
berry (1958) found that the crossbred steers weighed more at any age
than did the Hereford steers with which they were compared.
Burns, Koger, Warnick and Kincaid (1959) reported that the
weuning weights of Angus, Brahman and Hereford calves were lighter
than Santa Gertrudis or Brahman-Angus calves. Damon et al. (1)59)
studied the performance of crossbred beef cattle in the Gulf Coast
region. Crosses among Brahman and other breeds of cattle gave a
considerable advantage over the purebred cattle with respect to wean-
ing weights. However, the advantage w-s not so marked when slaughter
calf grades were considered. These crosses were generally superior
when the Brahman breeding was in the females. They obtained little
advantage by crossing the English beef breeds. Godbey et al. (1959)
reported that Angus cows produced lighter calves at weaning when mated
to Angus bulls than when mated to Brahman or Hereford bulls. Likewise,
Hereford cows produced lighter calves when mated to Hereford bulls than
when mated to Angus or Brahman bulls. Godley et al. (1960) found that
Brahmnan-Angus and Brahman-Hereford damis produced heavier calves than
Hereford-Angus or purebred Angus dams when mated to the same Shorthorn
Reynolds (1960) stated that breed group comparisons indicated
that hybrid vigor was an important factor influencing growth of calves
at the Range Cattle Station. Generally the breed groups with less
than 75 per cent of any one breed weaned the heaviest calves. Hargrove
(1960) individually fed Shorthorn, brahman and Shorthorn X Brahman
calves which were weaned at an average age of 86 days. The Shorthorn
calves gained 169 pounds, the Birahmin calves 224 pounds and the cross-
bred calves 238 pounds for a 147-day feeding period.
Bray (1933) stated that half-Brahman yearling heifers averaged
733 pounds while beef type non-Brahman heifers averaged 649 pounds.
Baker and Black (1950) found that yearling heifers out of Brahiman-Angus
cows were heavier than heifers out of purebred Angus cows. Warwick
(1950) reported that Brahman crossbred cattle were 46 pounds heavier
than British type cattle at 12 months of age. The crossbred cattle
were 80 pounds heavier at 24 months of age.
Liddon (1957) studied post-weaning growth of Angus, Brahman,
Devon and crossbred cattle at the Everglades Experiment Station. First-
cross females were superior in weight to the two parental breeds from
six months to five ve.rs of age. The FI females had a 7.7 to li.7
per cent advantage over the heavier of the parental breeds. The 3/4
Devon backcross group was equal in weight to the Brahman-Devon Fl
groups. When all of the purebreds were compared with all of the cross-
breds the crossbreds showed greater weight for age at all ages. Burns
et al. (1959) reported that yearling Santa Gertrudis and Brahman-Angus
heifers were heavier than Angus, Brahman and Hereford heifers. McDowell
et al. (1959) compared Jersey and Red Sindi-Jersey crossbred calves at
the Beltsville and Jeanerette stations. They found that the FI calves
were heavier than the purebred Jersey, 1/4 Jersey and 3/4 Jersey calves
at 6, 12 and 18 months of age.
I.TATERALS AI)D Li -T7i-lJF;
I'ature of D'ta
The data used in this study were obtained from the beef cattle
records of the EverClades Experiment Ctation, Belle Glade, Florida.
Records were available on Anr4us, Brahman, Devon and various crosses of
these breeds of cattle. The Devon herd was established at the station
in 1)31 and maintained until 1960. Herds of purebred Angus and
Brahmnn cattle were added and a crossbreeding program was started in
Very little culling took place in this population. Since
practic-ally all of the heifers were kept in the herd, little selection
was practiced except for the choice of sires used. Therefore, the
records used in this study were from a relatively unselected popula-
tion compared to most beef cattle herds today.
The data ansly. ed were the 205-uay weights of 933 calves and
the 12- and 1 -nonth weights of 41; heifer.. All of the heifers
having 12- :-nd l-month weights were included in the 205-day weight
analysis. The records covered the ten-year period from 195D through
1959. For 205-day weight, the data were classified by year of birth,
breed group, age of dam, se::, month of birth -nd lactation status of
the damr. For L-- and 1 '-mionth weights, the data were classified by
year and breed group.
Although reproduction was not considered in this study, the
nuRmber of cows bred and calves weaned by year iad breed group is
shown in table 16.
Factors Included in Analysis
The record of each individual was classified by year of birth
and the following factors.
Age of Dam. Age of dam was classified six ways.
1. Two years. Heifers which calved at two years of age.
2. Three years. Cows which calved at three years of age.
3. Four years. Cows which calved at four years of age.
4. Five years. Cows which calved at five years of age.
5. Six to eleven years. Cows which calved from six to
11 years of age were grouped together since prior
knowledge indicated that their influence on weaning
weight was similar.
6. Twelve to seventeen. Since nmjbers were small in the
higher age classifications, cows which calved from 12
to 17 years of age were grouped together.
1. Bull calves.
2. Steer calves.
3. Hieifer c .lves.
Month of Birth. Previous research and a preliminary inspection
of the data indicated that month of birth could be grouped into
1. Calves born during the months of December through June.
2. Calves born during the months of July through October.
3. Calves born in November.
Lactation tatuss of Dar:. The term lactation status refers to
the lactation record of the dam the previous year. It is based
on whether or not a damr weaned a calf the previous year. In
this study lactation status was classified two ways.
1. Lactating dams. Dams which weaned a calf the previous
2. Non-lactating dams. Dams which did not wean a calf
the previous year.
Breed Group. Breed groups were classified on the basis of the
breeding of the calf. There were three purebred groups and
five crossbred groups as follows:
1. Angus. Purebred Angus calves.
2. Brahm an. Purebred Brahman calves.
3. Devon. Purebred or high grade Devon calves.
4. Brahman-Angus Fl's. One-half Brahman one-half Angus
5. Brahman-Angus Backcrosses. Calves obtained by mating
Brahman or Angus bulls to BrlmL':n-Anus- Fl dams.
6. Brahman-Devon F 's. One-half Brhman one-half Devon
7. Brahman-Devon Backcrosses. Calves obtained by mating
Brahman or Devon bulls to Brahman-Devon F1 dams.
8. Brtahman-Devon Rotation Crosses. Calves resulting
from a Brahman-Devon rotational mating system.
9. Inter-se. Calves resulting from the inter-se mating
o' Brahman-Devon crossbreds.
Method of Analysis
Like most animal breeding data the records in this study were
not balanced with respect to their frequencies in the different sub-
claEses. Therefore, a specialized statistical analysis was necessary
in order to obtain the best estimates of the different parameters which
were of interest. Various authors have discussed the problem of
analyzing data involved in multiple classifications with disproportion-
ate subclass frequencies. For data where the frequency of observations
in some of the subclasses is zero, use of the method of fitting constants
by least squares seems to be the best solution. This method of analysis
was used in the present study.
Yates (1934) was the first to publish the method of least squares
for the analysis of multiple classifications with unequal numbers in
the different subclasses. Since then, others such as Hazel (1946),
Anderson and Bancroft (1952), Kempthorne (1952), Henderson (1953) and
Harvey (1960) have outlined this method and given the computational
details involved in its use.
Due to the complexity of the data and the computational facilities
available, it was impossible to analyze a model which included inter-
action effects by least squares. Consequently, it was necessary to use
some other method to obtain estimates of interaction. Estimates of
all first-order interactions were obtained using an approximate method
described by Hazel (1946) and Landblom (1955). Sum of squares for
interaction were obtained by summing the squared differences between
actual and expected subclass values divided by their subclass frequency.
Expected values were those obtained from the least squares analysis
assuming no interaction. One degree of freedom was subtracted for
each missing subclass in the two-way interaction tables.
Model for Weaning Data
The method of fitting constants by least squares was used to
analy-e the 205-day weights of 933 calves. The following mathematical
model was assumed to fit the biology involved.
Yijkpqrt = u + yi + bj ak + + my + 1r + eijkpqrt
i = 1, 2, .. 10
j = 1, 2,... 9
k = 1, 2, 6
p = 1, 2, 3
q = 1, 2, 3
r= 1, 2
Yijkprt = the 205-day weight of the tth calf in the ijkpqrth
u = the general mean,
yi = effect of i year,
bj = effect of jth breed group,
ak = effect of k age of dam,
Sp = effect of pth sex,
m = effect of th month of birth,
1r = effect of rth lactation status of darn,
eijkpqrt = random errors assumed to be LID (3, 6e2).
Using this model, 34 least squares e uations were derived rnd
are shown in table 14. Since these equations were not independent,
the following restrictions were imposed in order to obtain a solution.
A A A
i = -bj = = = tp = __ q = --r =
i J k p q r
The reduced equations were solved simultaneously by using matrix
inversion procedures. The matrix inverse is given in table 15. Sums
of squares for main effects were computed by subtracting the reduction
sum of squares, with a particular classification deleted, from the
reduction sum of squares obtained with all elements in the model.
Model for Post-Weaning Data
The following mathematical model was used to analyze the 12- ind
16-month weights of 415 heifers.
Yijk = o + yi + b + dDijk + eijk
i = 2, 10
j = 9
Yijk = the 1'- or 16-month weight of the kth heifer in the
oC = the theoretical population mean with equal subclass
frequencies when weaning age is zero,
yi = effect of ith year,
bj = effect of jt breed group,
d = partial regression of 12- or 18-month weight on age at
Dijk = age at weaning for the kth heifer in the ijth subclass,
eijk = random errors assumed to be NID (0, 6 2).
The restrictions were that y = b = 0. Estimates of the
A A -
general mean were obtained from the relationship u = o + d D, where D
is the mean age at weaning.
The 205-day weights of 933 calves were used in this analysis.
The unadjusted mean weight was 365 pounds while the adjusted mean or
general mean obtained from the least squares analysis was 372 pounds.
Effect of Year
Differences in 205-day weights due to year effects were found
to be highly significLnt (P<0.01), as shown in table 1. In these
data, years were an important source of variability as indicated by
the mean square for year being more than twice as large as any other
mean square. Although numerous reports state that year is an important
source of variability, it seems that under the conditions of this
study years were more variable than would be expected from a review
of the literature.
Also, it is interesting to note that year was involved in all
of the significant interactions (table 2). There were significant
interactions of year with breed, sex, month of birth and lactation
status. Age of dam was the only classification not involved in an
interaction with year.
The least squares effects by year are given in table 3. The
range in year effects was from 44 pounds in 1956 to -101 pounds in 1958.
Table 1.--VARIANCE AlALY;IS FOR MAIN EFFECTS IilFLU]EICITG 205-DAY ULIGHTj
Source df SS MS
R(u,y,b,a,c,nm,l) 27 2,950,32'
R(u,b,a, s,m,l) lc 1,165,90
R(u,y, s,m, ) 19 2,169,0o4
R(u,y,b,s,m,l) 22 2, 47,y
R(u,y,b,, ,m,l) 25 2,770,747
E(u,y,b,,0,l1) 25 2,905,954
R(u,y,b,',c, m) 26 2,946,7!7
Year 9 1,7c4,737 19&,304**
Breed 8 7cl, 2C`0 97,660**
Age of D'-m 5 102,70 20,556**
Sex 2 179, cO 89,790**
Month of Eirnth 2 44,373 22,187**
Lactation :t.tus 1 3,5 1 3,561
Residu-l 905 3,344,204 3,695
Total 932 6,94,31
**Significant at J.01 level of probability.
Table 2.--APPROXIMATE MEAN L..jJikUi FOR FIRST-OPDER IITE]RACTIONS
Source df SS MS
Year x Breed 58 373,507 6,440**
Year x Age of Dam 39 152,378 3,907
Year x Sex 16 138,161 ,635*
Year x Month of Birth 18 161,064 8,949-
Year x Lactation Ltatus 9 7;,251 ,361*
Breed x Age of Dam 33 147,680 4,475
Breed x Sex 16 93,015 5,813
Breed x Month of Birth 16 63,061 3,941
Breed x Lactation Status 8 28,822 3,603
Age of Dam x Sex 10 43,858 4,386
Age of D;aL x ionth of Birth 10 36,462 3,646
Age of Dam x Lactation Status 4 12,666 3,166
Sex x Month of Birth 4 11,216 2,804
Sex x Lactation Status 2 3,112 1,556
Month of Birth x Lactation Status 2 1,612 9,306
**Significant at 0.01 level of probability.
*Significant at 0.05 level of probability.
Table 3.--LEAST SHARES EFFECT BY YEARa
Classificntion Humber of 205-Day
1950 49 38.31
1951 67 -21.19
1952 79 -1.58
1953 115 -15.63
1954 0 27.39
1955 107 39.11
1956 99 44.17
1957 141 20.34
1958 14 -1oo.56
1959 56 -30.05
OVER-ALL (-) 933 372.23
'In this study, all effects "re deviations from the jver-?ll
Effect of Breed Groun
There were highly significant differences in 205-day weights due
to the effects of breed group. Also, there was a highly significant
interaction of breed group with year. The Brahnman-Angus backcross
calves were the heaviest in this study with an effect of 50 pounds
while the purebred Angus calves were the lightest with an effect of
-49 pounds (table 4).
The purebred Devon calves were heavier than the purebred Brahman
and Angus calves by 20 and 27 pounds, respectively. All of the purebred
groups were lighter than any of the crossbred groups.
In the Brahman-Angus crosses, the backcross calves were 63
pounds heavier than the Fl calves.
In the Brahman-Devon crosses, the backcross calves were 2 pounds
heavier than the Fl calves. The backcross calves were heavier than the
rotation-cross and inter-se calves by 6 and 24 pounds, respectively.
The Brahman-Angus F calves were 38 pounds lighter than the
Brahman-Devon Fl calves. In contrast to this, the Brahman-Angus back-
cross calves were 22 pounds heavier than the Brahman-Devon backcross
Effect of Sex
Sex of calf was found to be a highly significant source of
variability and was involved in a highly significant interaction with
Least squares estimates of the effects of sex revealed that
bull calves were 11 pounds heavier than steer calves and 3-pounds
Table 4.--LEAST SQUARES EFFECTS BY BREED
Classification Lumber of 205-Day
C lives Weight
BREED G (OUP (tj)
Angus 143 -49.35
Brahman 67 -42.07
Devon 171 -22.52
FI's 34 -12.74
Backcrosses 51 49.89
F1's 82 25.28
Backcrosses 106 27.39
Rotation Crosses 102 20.98
Inter-se 177 3.12
OVER-ALL (Q) 933 372.28
heavier than heifer calves (table 5). These effects are similar to
those reported by most research workers.
Effect of Age of D-am
There were highly significant differences due to age of dam.
The heaviest calves were produced by cows which were six to 11 years
old while the lightest calves were produced by cows which were two
years old (t-ble 5). Calves from cows2, 3, 4, 5 and 12 through 17
years old were lighter than calves from cows six through 11 years old
by 46, 26, 6, 12 and 5 pounds, respectively.
Effect of Lactation Status
The effects of lactation status were not significantly different.
However, there was a significant (P < 0.05) interaction between lacta-
tion status and year.
The calves from cows which were non-lactating the previous year
were 5 pounds heavier than calves from cows which were lactating the
previous year (table 6).
Effect of Month of Birth
Month of birth exerted a highly significant influence on 205-day
weights and was involved in a highly significant interaction with year.
Calves born during the months of December through June were heavier
than :;o'.'crmer calves by 7 pounds and July through October calves by
18 pounds (table 6).
Table 5.--LEAST SCU.nJS EFFECTS BY SEX AND AGE OF DAMI
Classification Number of 205-Day
Bulls 281 14.28
Steers 173 3.02
Heifers 479 -17.30
AGE OF DAM (ak)
2 years 61 -30.14
3 years 200 -10.40
4 years 155 9.42
5 years 151 4.30
6-11 years 333 10.82
12-17 years 33 11.00
OVER-ALL (Q) 933 372.28
Table 6.--LEAST SCUA.1- EFFECTS BY LACTATION STATUS AID IOI;TH OF BIRTH
Classification Number of 205-Day
LACTATION STATUS (1r)
Lactating 497 -2.44
Non-lactating 436 2.44
MOTHII OF BIRTH ( q)
December-June 368 8.32
July-October 249 -10.09
November 316 1.77
OVER-ALL (u) 933 372.28
12- and 18-Month Weight
The 12- and 13-month weights of 415 heifers were used in this
analysis. The unadjusted mean weight was 488 pounds for the heifers
at 12 months of age and 630 pounds for the heifers 'it 1i, months of age.
The adjusted means for the 12- and 18-month-old heifers were 485 and
632 pounds, respectively.
Effect of Year of Eirth
Year of birth exerted a highly significant influence on the 12-
and 18-month weights of the heifers in this study (tables 7 and 8). The
magnitudes of the mean squares for ye.r in respect to breed were similar
to that found in the 205-day weight analysis where the year mean square
was more than twice as large as the breed mean square.
The year x breed interaction mean squares are given in table 9
and are not signific ,nt. There was tremendous variability in the year
effects (table 10). The range in year effects for 12-month weight was
166 pounds while for 18-month weight it was 215 pounds.
Effect of1 Breed Group on 12-Month Weight
There were highly significant differences in the 12-month
weights due to breed group. The purebred Angus heifers were the
lightest breed group while the Brahrman-Devon 1l' heifers were the
heaviest (table 11).
The purebred Devon heifers were 18 pounds heavier than the
Brahman -heifers and 76 pounds heavier than the Angus heifers.
T-ble 7.--VARIAICE ANALYSIS FOR 12-IO~TH- '.,:77r
Source df SS MS
R( w,y,b,dD) 18 2,027,398
R( o,b,dD) 9 617,455
R( -,y,dD) 10 1,407,129
R( ,y,b) 17 1,886,742
Year 9 1,409,944 156,660*
Breed 8 620,269 77,534**
Regression of Weight
on Age at Weaning 1 140,656 140,656**
Residual 396 1,396,746 3,527
Total 414 3,424,145
**Significant at 0.01 level of probability.
Table 8.--VARIAIICE AliALYSIS FOR 1t-MOI1TH WEIGHT
Source df SS MS
R( o,y,b,dD) 1l 2,530,362
R(o ,b,dD) 9 523,763
R(x ,y,dD) 10 1,87, 56o
R( ,y,b) 17 2,51L,703
Year 9 2,006,599 222,955**
Breed 8 642,802 80,350**
Regression of Weight
on Age at Weaning 1 17,659 17,659
Recidual 396 1,830,853 4,623
Total 414 4,361,215
**Significant at 0.01 level of probability.
Table 9.--IITERACTIOII OF YEAR WITH BREED
Source df S MS
Year x Breed (12-.onth Weight) 54 225,262 4,171.5
Year x Breed (1E-1onth Weight) 54 33(,91 6,223.9
Table 10.--LEAST SQUARES EFFECTS OF YEAR OF BIRTH Oil 12- AND 18-MOflTI
Classification Lumber of 12-M'onth 18-Month
Heifers Weight Weight
1950 28 -6.22 -15.54
1951 35 -)4.46 -49.15
1952 29 -50.90 -37.30
1953 45 -47.76 -52.50
1954 31 -23.83 4.70
1955 47 111.85 106.36
1956 50 87.32 129.76
1957 63 54.51 -84.94
1958 60 -50.18 30.52
1959 27 -20.33 -31.91
OVER-ALL (u) 415 485.46 631.90
Table 11.--LEAST SCSUIj S EFFECTS OF BREED ON 12- AFD l8-rC!.Thi WEIGHTS
Classification Number of 12-Month 18-Month
Heifers Weight Weight
BREED GOUP (bj)
Angus 52 -89.00 -85.59
Brahman 33 -30.89 -47.94
Devon 67 -12.99 -3.61
Fl's 17 29.98 5&.94
Bz-ckc losses 22 5.25 -5.13
FI's 45 58.72 64.12
Backcrocses 48 29.65 1&.96
Rotation Crosses 48 26.83 21.71
Inter-ue 83 -17.75 -21.46
OVER-ALL (u) 415 485.46 631.90
In the Brahman-Angus crosses, the FI heifers were 25 pounds
heavier than the backcross heifers. Both the FI and backcross groups
were heavier than the purebred Angus and Brahman heifers.
In the Brahnu. n-Devon crosses, the F1 heifers were 29 pounds
heavier than the backcross heifers. 1'Te Fl heifers were 32 pounds
heavier than the rotation-cross heifers and 76 pounds heavier than the
inter-se heifers. All of the Braiiman-Devon crosses were heavier than
the purebred Brahiman and Devon heifers with the exception of the inter-se
heifers. The inter-se heifers were 13 pounds heavier than the Br-hman
heifers but were 5 pounds lighter than the Devon heifers.
The Brahman-Devon Fl and backcross heifers were 29 and 25 pounds
heavier than the Br-'lmian-Angus FI and backcross heifers.
Effect of Breed Group on l8-Month Weight
Breed Croup exerted a highly significant influence on l1-month
weights. The purebred Angus heifers were the lightest breed group
while the Brahman-Devon FI heifers were the heaviest (table 11).
The purebred Devon heifers were 44 pounds heavier than the
Brahman heifers and 82 pounds heavier than the Angus heifers.
In the Brahman-Anv. u. crosses, the F1 heifers were 64 pounds
heavier than the backcross heifers.
In the Brahman-Devon crosses, the Fl heifers were 45 pounds
heavier than the backcross heifers. The Fl heifers were 42 pounds
heavier than the rotation-cross heifers and 86 pounds heavier than the
The Brahman-Devon FI and backcross heifers were 5 and 24 pounds
heavier than the Brahman-Angus F1 and backcross heifers.
The purebred Angus and Brahman heifers were lighter than any of
the crossbred groups. The purebred Devon heifers were heavier than the
inter-se and Brahman-Angus backcrosses but lighter than the other cross-
Regression of Weight on Age at Weaning
Table 12 gives the partial regression coefficients for the re-
gression of 12- and 13-month weights on age of calf at weaning. The
partial regression coefficients are 0.77 pounds for 12-month weight and
0.27 pounds for 13-month weight.
Table 12.--PARTIAL RGC. L IOli COEFFICIEnITS FOR REGRESSION OF WEIGHT OI
AGE AT WEANING
12-Month Weight 1-L-Mionth Weight
Regression of 12- *nd lk -Month
Weight on Age at Weaning 0.7744585 0.2744128
Influence of Age of Dam
In order to determine if calves from two- and three-year-old
cows were as heavy at 12- and lb-months of age as calves from older
cows, age of dam was placed in the post-weaning model. This gave a
valid comparison of the heifers from the two- and three-year-old cows
and the older cows. Using this comparison, there were no significant
differences in the 12- or 18-month weights due to the influence of age
In general, the results of this study are in agreement with the
published reports of other similar investigations. However, the envi-
ronmental conditions during the period of this study caused the dependent
variables to fluctuate widely. This is shown by the tremendous year to
year variability in the 205-day, 12- and 18-month weights. An indication
of the magnitude of the year effects is shown in table 13. The square
of the multiple correlation coefficient gives the amount of variability
in the dependent variable that can be explained by a knowledge of the
independent variables. It is interesting to note that if year is omitted
from the model only about 18 per cent of the variability can be explained
by a knowledge of the other independent variables. However, when year
is included in the model R2 is increased to approximately 47 per cent.
Breed group was the only other classification which changed R2 greatly
when omitted from the model.
Even though most research workers agree that year effects are an
important source of variability, the variation in year effects found in
this study is greater than would be expected from a review of the litera-
ture. It is interesting to note that year was involved in significant
interactions with breed group, sex, month of birth and lactation status.
None of the other first-order interactions was significant. Also, it
should be pointed out that even though there was a highly significant
Table 13.--IMULTIPLE CORRELATION CCOFT iCTI:Ti WITH C. iTTI:i CLASSIFICATIONS
01 ITT'ID FROI I1ODLL
Classificatlon Oaitted Ri2
All Elements in Model 0.6646 0.4687
Year 0.4303 0.1852
Breed Group 0.5-70 0.3446
Age of Dam 0.6726 0.4524
Sex 0.6635 0.4402
Month of Birth 0.6795 0.4617
Lactation Status 0.6642 0.4681
year x breed group interaction for 205-day weight there were no significant
interactions for 12- and 1-month weights. From these results the fol-
lowing statements about the Everglades Experiment Station beef cattle
population appear to be justified:
1. Environmental influences create much variability in beef
2. IExperiments involving beef cattle should be designed so that
the desired comparisons can be made on a within year basis.
3. Since year was involved in all significant interactions,
experiments should be repeated for several years before
any definite conclusions are drawn.
The effects of sex were in close agreement with most estimates
obtained under different conditions. Almost all investigations have
revealed that bulls are heavier than steers and that steers are heavier
than heifers. The same situation was true in this study. However,
contrary to most reports, sex was involved in an interaction with year.
This may be due to the fact that the year to year variation was ex-
The variability due to age of dam in this study was less than
that usually reported. The differences between the two- and three-year-
old cows and the mature cows were not as great as those obtained in
most studies. The fact that age of dam did not influence 12- and 18-month
weights gives validity to the practice of adjusting weaning weights for
the effects of age of dam before replacements are selected.
The significant influence of month of birth indicates that this
factor should be considered in beef cattle research at the Everglades
Lactation status of the dam the previous year did not exert a
significant influence on weaning weights. Even though the effect of
lactation status was not significant, the calves from cows which were
non-lactating the previous year were 5 pounds heavier than calves from
cows which were lactating. Also, there was a significant interaction
(P < 0.05) between lactation status and year. However, the multiple
correlation coefficients obtained with lactation status in and out of
the model were practically the same. Therefore, very little precision
was gained by including lactation status in the model.
There were significant differences (P < 0.01) in the 205-day,
12- and 18-month weights due to the influence of the different breed
groups. With the exception of year, breed group was the largest source
of variability in the 205-day weights. Since one of the primary objec-
tives of crossbreeding is to increase weaning weights, this variability
created by breed groups would be expected if the breeding programs under
consideration were successful. The results of this study clearly point
out that increased weaning weights can be obtained through the use of
crossbreeding progroansinvolving Angus, Brahman and Devon cattle at the
Everglades Experiment Station. Even though this is true, careful con-
sideration should be given to other important factors before a cross-
breeding program is used in an economic enterprise. Certainly the
reproductive rate should be considered since it probably influences
economic return more than any one single factor.
All of the crossbred groups in this study involved the Brahman
breed of cattle. This means that rate of reproduction should be evaluated
even more critically because most evidence indicates that the rate of
reproduction in Brahman cattle may be lower than in some of the other
breeds. Also, there is the possibility of partial genetic incompatibility
between the Brahman and European breeds of cattle as far as reproduction
is concerned (Koger, 1960). Other very important factors to be con-
sidered are the practical limitations of crossbreeding programs.
The relative influence of breed group on 205-day, 12- and 10-
month weights is shown in figure 1. At 205 days of age, all of the pure-
bred groups were lighter than any crossbred group. For the Brahman and
Angus groups, this held true at 12 and 18 months of age. However, the
Devon heifers were heavier than the inter-se heifers at 12 and 18 months
of age and heavier than the Brahman-Angus backcross heifers at 18 months.
It is interesting to compare the Fl's and backcrosses at different
ages. At 205 days of age, the Brahman-Angus and Brahman-Devon backcross
calves were the two heaviest breed groups. However, at 12 and 18 months
of age they were considerably lighter than their respective FI breed
groups. Since these calves from F1 dams were heavier at weaning but
were lighter at later ages, it seems plausible to state that the F1
cattle expressed hybrid vigor in the form of growth potential and milking
or mothering ability.
In general, the Brahman-Devon inter-se cattle did not perform
as well as the Fl, backcross and rotation-cross breed groups. A pos-
sible explanation for this is the loss of hybrid vigor in the inter-se
With the exception of the Brahrman-Devon FI and backcross groups,
the Brahman-Devon rotation-cross cattle were the only breed group whose
weights were above the mean of the population at all ages. Considering
.......... .-D tat
1 \ B1-A ck
0*oinm -mu -ia roll o m,em m l l
Figure 1. Relative influence of breed group on 205-day,
12-month and 13-month weights.
only the weights of the different breed groups and the practical aspects
of the different breeding program involved, the Brahman-Devon rotation-
cross cattle may possibly be one of the best breed groups in this popula-
tion from an economic viewpoint.
The regression coefficients obtained from the post-weaning analysis
point out one interesting fact. Age differences within a breeding season
do not influence the 13-month weights of heifers very much. This is
indicated by a partial regression coefficient of 0.27 pounds for the
regression of 18-month weights on age at weaning. If the same situation
prevails in beef cattle under other conditions, care should be taken in
the interpretation of the commonly used measurement "weight per day of
Estimates of the factors which influenced the 205-day, 12- and
18-month weights of the Everglades Experiment Station beef cattle popula-
tion were obtained using the method of fitting constants by least squares.
This population contained Angus, Brahman, Devon, Brahman-Angus and
Brahman-Devon cattle. The 205-day weights of 933 calves and the 12-
and l1-month weights of 415 heifers were included in the analyses. The
records covered the ten-year period from 1950 through 1959.
There was tremendous variability in the year effects. The ranges
in year effects were 145 pounds for 205-day weight, 166 pounds for 12-
month weight and 215 pounds for 18-month weight. All of the significant
first-order interactions were involved with year.
Bull calves were 11 pounds heavier than steer calves and 32 pounds
heavier than heifer calves at 205 days of age.
The heaviest calves were produced by cows which were six to 11
years old while the lightest calves were produced by cows which were
two years old. Calves from cows 2, 3, 4, 5 and 12 through 17 years old
were lighter than calves from cows six through 11 years old by 46, 26,
6, 12 and 5 pounds, respectively.
There w-is a significant influence of month of birth on 205-day
weights. Calves born during the months of December through June were
heavier than November calves by 7 pounds and July through October calves
by 18 pounds.
The effects of lactation status were not significantly different.
However, there was a significant (P< 0.05) interaction between lactation
status and year.
All of the purebred breed groups were lighter than any of the
crossbred groups at 205 days of age. For the Brahman and Angus groups,
this held true at 12 and 18 months of age. However, the Devon heifers
were heavier than the inter-se heifers at 12 and 13 months of age and
heavier than the Brahmarn-Angus backcross heifers at 18 months.
The Brahman-Angus and Brahman-Devon backcross calves were the two
heaviest breed groups at 205 days of age. At 18 months of age, the
Erahman-Angus and Brahmian-Devon F heifers were the heaviest breed groups.
With the exception of the Brahman-Devon FI and backcross groups, the
Brahman-Devon rotation-cross cattle were the only breed group whose
weights were above the mean of the population at all ages. The Brahman-
Devon inter-se cattle did not perform as well as the Fl, backcross and
rotation-cross breed groups.
Partial regression coefficients of 0.77 and 0.27 pounds were
obtained for the regression of 12- and 18-month weights on age at weaning,
Table 14.-- IGCLAL LEAST SCUARED'S UATIOTNS
u 0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9
u : 933
Y2 : 79
y : 140
bc : 102
s : 479
49 67 79 115 80 107 99 141 140 56
16 25 30
2 7 11
21 25 12
7 11 12
7 6 5
17 21 20
27 41 35
24 24 36
12 34 24
23 15 23
33 48 54
4 5 3
41 5 78
56 71 62
43 35 39
34 61 26
22 45 75
54 70 99
45 71 41
Table 14 (continued)
b b b3 b4 b b b b 9
34 51 82
8 9 15
7 1 4
1 12 5
6 9 11 16 4 15
36 16 36 2 13 1 31 18 47
22 6 20 4 10 6 15 29 43
19 12 21 6 9 18 17 16 33
45 33 74 18 8 57 25 34 39
15 11 4 2 1
60 24 53 7 17 19 27 32 42
18 6 32 9 10 14 25 20 39
65 37 86 18 24 49 54 50 96
51 28 70 12 23 24 44 45 71
57 10 43 12 14 30 26 12 45
35 29 58 10 14 28 36 45 61
89 33 78 16 24 54 63 55 85
54 34 93 18 27 28 43 47 92
Table 14 (continued)
al P2 a3 a4 a a El s s5
a1 a2 35 26
Table 14 (continued)
1 1 m n3 1 12 I
Table 1,. --fVERSE OF REDUCED COi: :CL! T :AT:.I:D7
Y0 Y1 Y2 Y3 Y4 Y5
yo: .207126 -.00737 -.01352 -.017593 -.029396 -.024643
yi: .147307 -.309012 -.009006 -.019945 -.o01341
Y2: .130372 -.008557 -.0163.1 -.013958
Y3: .090040 -.006315 -.007476
Y4: .120971 -.)091l01
Inverse of corrected sum of squares and crossproducts.
Values in table are actual values divided by 10.
Table 15 (continued)
Y6 7 Y8 bl b2 b3 b5
-.022348 -.025341 -.026596 .012222 .000565 .001234 .020518
-.019904 -.019765 -.o1 943 .01o176 -.0001D7 -.005710 .017283
-.013687 -.018210 -.01150 .00186 .0130C -.006457 .008594
-.001146 .001705 -. 009907 .3,221 .003319 -.000879 -.003140
-.001106 -.003501 -.007231 -. )'162 .005135 .005972 .003462
-.005804 .002277 -.003'972 -. 30 07 -. 004111 .002160 .002985
.101362 -.004854 -.000177 -.003515 .007774 -.002479 -.008940
.088716 -.o00487L -.00662 -.000482 -.000520 -.011577
.0.-2104 -.006114 .001444 .006125 -.012592
.077159 -.012082 -.000994 -.011084
.136038 -.007661 -.028184
Table 15 (continued)
b6 27 b b a a 2a3
-.045771 -.002347 .016208 .019182 -.005705 .002531 -.002950
-.027235 -.008983 .017805 .016532 -.010982 .300559 -.003092
-.000476 -.020689 .012764 .008395 -.013933 .007878 .002677
-.003821 -.oo3884 .005485 .00o193 -.010563 .300843 .006697
.010941 .000353 -.006770 -.003146 .012694 -. 307781 .006907
.018611 .005336 -.009916 -.009729 .013375 .012567 -.007581
.006894 .010824 -.013114 -.011252 .005837 -.001090 .003209
.013753 .011478 -.012005 -.012104 -.002086 .003718 .000286
.013o38 .002497 -.006733 -.009322 .005321 -.004757 -.001366
-.016111 -.005943 -.002171 .002989 -.001184 -.300659 .003850
-.014052 -.013173 -.013895 -.010659 .011735 -.004641 .000777
-.003895 -.003530 -.005019 -.000913 .008520 .000996 .002703
-.035263 -.017285 -.012973 -.005395 -.030934 -.002120 -.000389
.135222 -.009499 -.020978 -.017818 .015146 .006573 .001836
.098140 -.012974 -.005089 -.016733 -.008631 .002953
.100624 .004666 -.000932 .000509 -.009891
.066826 -.008922 -.005057 -.005893
.167941 -.006960 -.022807
T-ble 15 (continued)
A A A A A
a4 a5 s1 s5 3 1
-.010636 .005841 -.003384 -.005694 .002349 .007414 .005833
.001732 -.000542 -.003473 -.001349 -.000836 -.001332 -.000565
.003302 -.001169 -.00L599 -.000500 -.001069 .005455 .000500
.00803 .002621 .009527 .003153 -.000695 .000946 -.001994
.o00286 -.003006 .00733 8i .003873 -.00374C .000302 -.002870
.000369 -.004699 .003071 .000470 .000937 -.002030 .007577
-.003711 -.000731 -.006041 -. 002191 -.000491 .304433 -.000561
.004802 -.001145 .017772 .003630 .00~291 -.001057 .000053
.000569 -.002527 -.010756 .001053 .003351 -.006662 -.004782
.007580 .007495 -.005046 .00733 .0o0044 .305272 -.002799
-.005150 -.008426 -.001768 -.001302 -.001659 -.oo2627 .002066
.002186 -.003076 -.000399 .000791 -.000494 -.000642 .002603
.002711 .012559 -.3 03158 -.000502 -.001: 5 .002866 -.002251
-.006620 -.017392 .003875 -.000142 .003117 -.001749 .000492
.003358 .009540 .003797 .000130 .00'328 -.001476 -.005727
-.000519 .000934 -.001925 .000062 -.003947 -.002922 .000525
-.001731 .006554 .000697 -.001449 -.001377 .000420 -.000576
-.003022 -.029371 .004351 .00' 10 -.009395 .003367 .017911
-.003471 -.001230 -.002436 -.000513 .000906 -.001313 .011865
-.ooo00 6 .004428 .003152 .D02359 .002415 -.000285 -.003842
.069369 .007765 -.000575 -.302437 .000921 .000133 -.006581
.048407 -.001668 -. 00987 .003754 -.001176 -.0 0700
.032351 -. 04597 .002224 -.0302210 -.000134
.020650 .000411 -. 001O' .000246
.022868 -.009693 -.001600
0 UO-I 0\ -
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Anderson, R. L. and T. A. Bancroft. 1952. Statistical Theory in
Research. iMcGraw-Hill Book Co., Inc., New York.
Baker, A. L. and W. H. Black. 1950. Crossbred types of beef cattle
for the Gulf Coast Region. USDA Cir. 644.
Black, W. H., A. T. Semple and J. L. Lush. 1934. Beef production
and quality as influenced by crossing Brahman with Hereford and
Shorthorn cattle. USDA Tech. Bul. 417.
Botkin, M. P. and J. A. Whatley. 1953. Repeatability of production
in range beef cows. J. Animal Sci. 12:552.
Bray, C. J. 1933. Beef cattle production in Louisiana. Louisiana
Agr. Exp. Stat. Bul. 244.
Brown, C. J. 1958. Heritability of weight and certain body dimen-
sions of beef calves at weaning. Arkansas Agr. Exp. Stat. Bul. 597.
Brown, C. J. 1960. Influence of year and season of birth, sex, sire,
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James H. Meade, Jr. was born November 1, 1932, at Vicksburg,
Mississippi. He graduated from Jett Vocational High School in
1950. In May, 1954, he received the degree Bachelor of Science
in Agriculture from i ississippi State University. After serving
two years in the United States Army, the author returned to
Mississippi State University where he received the degree Master
of Science in Agriculture in January, 1959.
The author is now a candidate for the degree Doctor of
Philosophy at the University of Florida.
This dissertation was prepared under the direction of the chairman
of the candidate's supervisory committee and has been approved by all
members of that committee. It wis submitted to the Dean of the College
of Agriculture and to the Graduate Council, and was approved as partial
fulfillment of the requirements for the degree of Doctor of Philosophy.
June 5, 1961
Dean, College of Agriculture
Dean, Graduate School
UNIVERSITY OF FLORIDA
3 1262 08666 938 8