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Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 772
Title: Factors influencing weaning performance in Florida BCIA herds
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 Material Information
Title: Factors influencing weaning performance in Florida BCIA herds
Series Title: Bulletin - University of Florida Agricultural Experiment Station ; 772
Physical Description: Book
Language: English
Creator: Franke, D. E.
Pace, J. E.
Martojo, H.
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida,
Publication Date: 1975
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Bibliographic ID: UF00027624
Volume ID: VID00001
Source Institution: University of Florida
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    Literature cited
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bulletin 772 (technical)


Actors


Influencing Weaning Performance

in Florida BCIA Herds
D.E. Franke, J.E. Pace, and H. Martojo


I U


Agricultural Experiment Stations
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
J. W. Sites, Dean for Research


I U


May 1975
















FACTORS INFLUENCING WEANING
PERFORMANCE IN FLORIDA BCIA HERDS

D. E. Franke, J. E. Pace, and H. Martojo
Dr. Franke is an Associate Professor and Mr. Pace is a Pro-
fessor in the IFAS Animal Science Department, University of
Florida, Gainesville 32611. Dr. Martojo's present address is: Col-
lege of Agriculture, Bogor, Indonesia.
Appreciation is expressed to Mrs. Nell Epperson for assistance
in obtaining BCIA records for analysis.











This public document was promulgated at an annual cost
of $434.99 or a cost of 211/2 cents per copy to provide infor-
mation on factors influencing performance in herds enrolled
in the Florida Beef Cattle Improvement Association.







FACTORS INFLUENCING WEANING
PERFORMANCE IN FLORIDA BCIA HERDS

Weaning performance is one of the major economically im-
portant traits in beef cattle production. It is a function of wean-
ing weight and weaning score and is influenced primarily by the
genetic potential of the calf to grow and fatten in the maternal
environment provided by the dam. Some of the non-genetic fac-
tors contributing to variation in weaning performance are year
of calf birth, sex of calf, age of dam and age of calf. Performance
is influenced directly by some of these factors, whereas others
act through the maternal environment. It is important that the
magnitude of these non-genetic effects be known so that adequate
correction factors are available to adjust data for more effective
evaluation of replacements. The ability to recognize genetically
superior animals in purebred herds is an ever challenging prob-
lem for cattlemen. The influence of these factors on weaning
weights of straightbred calves has been studied in Beef Cattle Im-
provement Association enrolled herds in Georgia (Warren,
Thrift, and Carmon, 1965), Virginia (Marlowe, Mast, and Schal-
les, 1965), Iowa (Sellers, Willham, and deBaca, 1970), Oklahoma
(Cundiff, Willham, and Pratt, 1966) and New York (Cunning-
ham and Henderson, 1965).
The purpose of this study was to determine the importance
and magnitude of effects of herd, year, dam age, calf sex, calf
age, and most first-order interactions on weaning weight and
score in Angus, Brahman, Charolais, Hereford, and Santa Ger-
trudis herds enrolled in the Florida Beef Cattle Improvement As-
sociation (FBCIA).


Materials and Methods

Weaning records collected and processed by the FBCIA from
1960 to 1972 were available for this study. Procedures to estimate
the importance and magnitude of the effects and first-order in-
teractions influencing weaning weight and score required that
herds have records in at least two years. Those herds not meeting
this requirement as well as calf records with missing or question-
able observations were deleted from the data set. The number
of herds and records used and average weights and scores of
calves at weaning within breed are shown in Table 1. Weaning
records on 1,363 Angus calves from 6 herds, 3,528 Brahman
calves from 4 herds, 2,483 Charolais calves from 9 herds, 2,042







Hereford calves from 4 herds, and 2,840 Santa Gertrudis calves
from 3 herds met the requirements.
The calving season of herds contributing data was from No-
vember through April. Records were available on bull and heifer
calves in Angus, Brahman, Charolais, Hereford, and Santa Ger-
trudis herds. Steer records were available in most Santa Ger-
trudis herds. Cow ages were grouped for study according to rec-
ommendation of the Beef Improvement Federation (BIF) and
according to the cow age classification currently used by the
FBCIA. These classifications are: (1) two-year-old cows, (2)
three-year-old cows, (3) four-year-old cows, (4) cows five
through ten years old, and (5) cows eleven years old and older.
A mathematical model similar to the following was used to
analyze weaning weight and score data within the five breeds:

Yijlkm= ~+hj +yj +a + s, + (hy) j+ (ha),,+ (hs),,+ (ya)jk

+ (ys), + (as),, +b, (X-X) +b, (X2-X2) +eijkm

where

Yijklm=weaning weight or score of the mth calf of
the Ith sex born in the jth year from the
kth age of dam,
= overall least squares mean common to all
effects,
hi = effect of the ith herd,
y, = effect of the jth year,
ak = effect of the kth age of dam,
sI = effect of the Ith sex of calf,
(hy) ij ... (as) k = first order interaction effects,
b = partial linear regression of weight or score
on age of calf (X) at weaning.
b2= partial quadratic regression of weight or
score on age of calf (X)2 at weaning, and
eijklm= random error associated with the mth ob-
servation, N (0,o).

All first-order interactions between the main effects were not
fitted because of certain limitations of the data. All effects except
error were assumed to be fixed. Score was not studied in the Charo-
lais data because of missing observations in some breds for most
of the years. It was shown by Swiger et al. (1962) and Marlowe








TABLE 1. NUMBER OF HERDS AND RECORDS
SCORE AT WEANING.


AND AVERAGE AGE, WEIGHT AND


A B C H SG


Herds 6 4 9 4 3

Records 1,363 3,528 2,483 2,042 2,840

Average Age 211 227 235 240 219
sdl 40 30 37 38 34

Average Weight 419 417 551 436 479
sd 92 79 113 76 86
2
Average Score 12.2 10.3 2 12.0 10.1
sd 1.4 2.0 1.6 1.7

2Standard deviation.
Not available on all records.


et al. (1965) that when calf age at weaning ranged more than
205+45 days, the probability was large that a non-linear relation-
ship existed between calf weight and calf age. Since 23% of the
calves in these data were weaned at ages outside the 205+45 day
range, statistical procedures to account for possible curvilinearity
were needed. Linear and quadratic covariance terms were in-
cluded in the model to account for the possible curvilinear rela-
tionship between weaning weight or score and calf age.

Weaning weights and scores were recorded by county, area,
or state Extension beef cattle specialists cooperating with the
FBCIA.

Results and Discussion

Angus calves were weaned at the youngest mean age of the
five breeds, 211 days, whereas Herefords were the oldest at wean-
ing, 240 days. Charolais calves averaged 551 pounds at weaning
and were heavier than calves from other breeds. They were fol-
lowed by Santa Gertrudis calves at 479 pounds, Hereford calves
at 436 pounds, Angus calves at 419 pounds, and Brahman calves
at 417 pounds. Brahman and Santa Gertrudis calves were graded
similarly, at 10.3 and 10.1, respectively, while Angus and Here-
ford calves were graded 12.2 and 12.0. respectively.

Least squares analysis of variance significance levels for fac-








TABLE 2. LEAST SQUARES ANALYSIS OF VARIANCE SIGNIFICANCE LEVELS FOR WEANING WEIGHT.

Source of A B C H SG
variation df SL df SL df SL df SL df SL
Herd (H) 5 ** 3 ** 8 ** 3 ** 2 *
Year (Y) 4 ** 7 ** 6 ** 7 ** 6 **
Cow age (CA) 3 4 ** 4 ** 3 ** 4
Sex (S) 1 ** 1 ** 1 *1 ** 2 **
H x Y 11 ** 6 **- 16 ** 7 **
H x CA 15 9 9 ns 8 ns
H x S 5 -* 3 ** 8 ns 3 ** 4 *
Y x CA 12 ** 25 24 ns 21 ns 20 ns
Y x S 4 ns 7 ns 6 ns 7 ** 12 **
CA x S 3 ns 4 ns 4 ns 3 ** 8 ns
Calf age (L) 1 **I 1 ** 1 ** *
Calf age (Q) 1 ** 1 ** 1 ** 1 ** 1 **
Residual 1297 2364 3456 3400 2419 6586 1966 2341 2764 3937
SP < .05
** P < .01


tors influencing weaning weight and weaning score are shown
in Tables 2 and 3 respectively. Least squares means for factors


influencing weaning weight and score
5, respectively.


are shown in Tables 4 and


Herd, year, cow age, and sex were sources of variation sig-
nificantly influencing weaning weight (P <.05 or P <.01) in each
breed. Herd differences within each breed were expected to occur
because of different management practices, lines of breeding of
cattle, and goals of the respective owners. Least squares means
for weaning weight adjusted to 205 days of age were 402, 405,
507, 392, and 455 pounds for the Angus, Brahman, Charolais,
Hereford and Santa Gertrudis breeds, respectively. Herd wean-
ing weights ranged from 317 to 444 pounds in the Angus, 362 to
450 in the Brahman, 367 to 601 in the Charolais, 367 to 409 in
the Hereford and from 425 to 479 in the Santa Gertrudis.

Year effects in general revealed no definite trend over time,
except that in the Charolais a slight positive trend for weaning
weight was indicated. Most studies have found year effects to
have a significant influence on weaning weight of straightbred
calves (Harwin et al., 1966; Hohenboken and Brinks, 1969; Sell-








TABLE 3. LEAST SQUARES ANALYSIS OF VARIANCE SIGNIFICANCE LEVELS FOR WEANING SCORE.

Source of A B H SG
Variation df SL df SL df SL df SL

Herd (H) 5 ** 3 ** 3 ** 2 **

Year (Y) 4 ** 7 ** 7 ** 6 **

Cow age (CA) 3 ns 4 3 ** 4 **

Sex (S) 1 ** 1 ns 1 ns 2 ns

H x Y 11 ** 6 16 ** 7 **

H x CA 15 ns 9 ns 9 ns 8 ns

H x S 5 ** 3 ** 3 ns 4 **

Y x CA 12 ** 25 21 ns 20 **

Y x S 4 ns 7 ns 7 ns 12 **

CA x S 3 ns 4 3 ** 8

Calf age (L) 1 ** 1 ** 1 ** 1 **

Calf age (Q) 1 ** 1 1 ** 1 **

Residual 1297 1.3 3546 3.1 1966 1.7 2764 2.0


1Charolais data
*P < .05
**P < .01


not analyzed for score.


ers et al., 1970, Warren et al., 1965). Significant year effects can
be associated with variations in yearly rainfall, temperature, and
management practices that change from year to year. An inter-
est in the trend of yearly weaning weight occurs because most
ranchers expect increased weaning weights from year to year as
a result of selection for genetically superior replacements and
improved management. Since all herds were not represented in
all years in these data, the yearly variations could reflect the
herds that were represented at that time.

Significant age of dam effects on weaning weight were found
for the Brahman, Charolais, Hereford, Angus, and Santa Ger-
trudis breeds. In the Angus and Hereford breeds, the number of
records from 2-year-old cows was too few to be included in the
study. Younger cows in each breed as well as aged cows weaned
smaller calves than mature cows. These results are in general
agreement with other reports (Warren et al., 1965; Minyard and
Dinkel, 1965), although the range in weaning weights by age







TABLE 4. LEAST SQUARES MEANS FOR FACTORS
WEIGHT ADJUSTED TO 205 DAYS.


INFLUENCING WEANING


Factor A B C H SG


Herd










Year










Cow age


v
1
2
3
4
5
6
7
8
9

64
65
66
67
68
69
70
71
72

2
3
4
5-10
11 +


Calf Sex B
S
H


426 426 532 413 490
- 439
378 384 482 369 438


of dam classification for each breed is slightly less than reported
by most researchers, including a summary of age of dam effects
by Petty and Cartwright (1966). Brahman and Santa Gertrudis
3-year-old cows weaned calves that were more similar to mature
cows than were calves from Angus, Hereford, or Charolais cows.
This would suggest that the maternal ability of young cows in
these two breeds may be superior to that of similar age British
cows. It is generally recognized that young cows are still growing
while they are nursing their first, second, and sometimes third
calf. Thus, additional nutrients are required by the young cow
to meet body growth requirements as well as those normally re-
quired for body maintenance, lactation, and reproduction. The
young growing cow may not be able to meet all the lactational







requirements and therefore gives her calf less milk than a mature
cow would offer. Aged cows have been found to have short or
poor teeth, thus hindering their grazing ability. This results in a
lowered amount of nutrients available and lactation generally is
reduced.
Sex-of-calf effects were found to be highly significant in all
breeds. Bulls were heavier than heifers by 48 pounds in Angus,
42 pounds in Brahman, 50 pounds in Charolais, 44 pounds in
Hereford, and 52 pounds in Santa Gertrudis calves. Santa Ger-
trudis steer calves weighed about the same as heifer calves. In-
formation was available to suggest that inferior bull calves were

TABLE 5. LEAST SQUARES MEANS FOR FACTORS INFLUENCING
WEANING SCORE ADJUSTED TO 205 DAYS.

Factor A B H SG

P12.4 10.5 11.8 9.6
Herd 1 12.5 12.2 11.8 9.7
2 12.9 10.2 12.0 9.9
3 12.3 9.4 11.5 9.3
4 12.9 10.2 11.7 -
5 12.1 -
6 11.4 -

Year 64 9.3 10.6 9.0
65 9.8 11.9 9.7
66 13.1 10.1 12.4 8.7
67 12.0 10.5 11.9 9.6
68 12.1 10.4 10.9 9.6
69 12.6 11.5 12.6 10.4
70 12.0 11.6 11.9 10.4
71 11.7 11.7 -

Cow age 2 10.0 8.8
3 12.2 10.5 11.5 9.7
4 12.3 10.6 11.8 9.9
5-10 12.5 10.9 12.0 1011
11 + 12.4 10.4 11.7 9.6

Calf sex B 12.2 10.5 11.7 9.7
S 9.4
H 12.5 10.5 11.8 9.8







castrated in these herds; therefore, the results would be expected.
Bull calves tended to be heavier than heifer calves by approxi-
mately 10% in each breed. This is in agreement with other BCIA
data (Swiger, 1961; Warren et al., 1965; Cundiff et al., 1966;
Marlowe et al., 1965).
The linear and quadratic effects of calf age significantly in-
fluenced weaning weight in each breed. Calf weaning weight
increased with calf age but at a decreasing rate. In other words,
the growth curve of calves, from the youngest calf age to the old-
est calf age at weaning, was curvilinear. Most performance test-
ing organizations use a linear adjustment technique to correct
for calf age at weaning. Results from analyses of these data
suggest that when calf age ranges from 135 to 275 days, a linear
adjustment technique is not sufficient to adequately correct wean-
ing weight for extreme ages. Performance testing organizations
normally recommend that calf data not be processed if calf age
is outside the 20545 day range. This recommendation is con-
sistent with results from other studies (Swiger et al., 1962 and
Marlowe et al., 1965). It should be understood that the linear
adjustment for calf age between 160 and 250 days may not cor-
rectly adjust weaning weight for age but is considered adequate.
Weaning score has been reported to be influenced by the same
environmental effects as weaning weight. Marlowe et al. (1965)
and Cunningham and Henderson (1965) reported similar herd
and year effects on score as those found in these data for Angus
and Hereford calves. Santa Gertrudis calves were scored lower
while Angus calves received highest scores. Weaning scores
tended to increase with advancing years except in the Angus
breed. A strong positive trend in score over time was noted in
Brahman calves.
The age of dam effect on weaning score was significant in the
Brahman, Hereford, and Santa Gertrudis breed but non-signifi-
cant in the Angus. Younger cows weaned calves which scored
less than calves from mature cows. This reflects the maternal
capabilities of young cows as compared to mature cows and is
similar to the influence of cow age on weaning weight. Aged cows
also weaned calves scoring lower than cows 5 to 10 years old.
Sex of calf generally has little effect on weaning score. This
was reflected by a significant sex-of-calf effect only in the Angus
breed. These results are in general agreement with Koch and
Clark (1955), Marlowe et al. (1958) and High (1970), who re-
ported an unimportant sex influence on weaning score. Signifi-







cant sex effects as found in the Angus breed were in agreement
with Marlowe et al. (1965) and Cunningham and Henderson
(1965). Angus bulls graded lower than heifers in this study. This
disagrees with Cunningham and Henderson (1965), where An-
gus and Hereford bulls graded higher than heifers. In other data,
however, Marlowe et al. (1965) found Angus and Hereford bull
calves to grade lower than heifer calves. In Brahman calves, no
difference in weaning score was found between bull and heifer
calves.
Age of calf tended to significantly influence weaning score in
each breed. In general, score was higher for older calves than
younger calves, but increased with age at a decreasing rate.

Interactions

Interactions that tended to be important in this study were
associated with herd, year, and sex of calf and occurred in all
breeds except the Charolais. Other researchers have reported
significant interaction effects when these variables were studied
(Swiger, 1961; Vernon et al., 1964; Harwin et al., 1966). The
basic suggestion from these significant interactions is that wean-
ing weight and weaning score should be adjusted on a within
herd, year and sex subgroup basis. Most performance testing or-
ganizations follow these procedures in adjusting calf weight for
age of dam and to 205 days.

Summary
Weaning records of Angus, Brahman, Charolais, Hereford,
and Santa Gertrudis calves processed by the Florida Beef Cattle
Improvement Association were available to study the influences
on weaning performance. Year, herd, sex of calf, age of dam, and
calf age were generally significant sources of variation influenc-
ing weaning weight and score within each breed. Adjusted 205-
day weaning weights for Angus, Brahman, Charolais, Hereford,
and Santa Gertrudis calves were 402, 405, 507, 392, and 455
pounds, respectively. Adjusted weaning scores for the four
breeds (Charolais excluded) were 12.4, 10.5, 11.8, and 9.6 re-
spectively. Interactions between breed, sex, and year were gen-
erally significant for weaning weight except in the Charolais.
These data suggest that calves outside the 205-45 day age range
should not be included in data to be processed because the linear
adjustment for calf age used by FBCIA does not accurately ad-
just the weaning weight of these calves to a 205-day weight.








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and phenotypic parameters of weaning traits in beef cattle. J. Anim.
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Harwin, G. O., J. S. Brinks, and H. H. Stonaker. 1966. Genetic and en-
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