EVALUATION OF A CENTRAL BULL TEST STATION by STANLEY MACK YOUNG, B.S A THESIS IN ANIMAL BPJ:EDING Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Approved ^jy^A. n' OjmA. Chairniin of the/t:o'^ittee 'H,v\> -^U^/v^vU- 0. (|-<,.c-.U-.> Accepted Dean of August, 1976 "^
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EVALUATION OF A CENTRAL BULL TEST STATION
by
STANLEY MACK YOUNG, B.S
A THESIS
IN
ANIMAL BPJ:EDING
Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for
the Degree of
MASTER OF SCIENCE
Approved
^jy^A. n' OjmA. Chairniin of the/t:o'^ittee
'H,v\>
-^U^/v^vU- 0 . (|-<,.c-.U-.>
Accepted
Dean of
August, 1976
" ^
i4D^A- - ' /
n, •••/ f_
ACKNOWLEDGEMENTS
I am most grateful to Dr. C. Boyd Ramsey for directioi
of this thesis and his encouragement during m.y graduate
study. The assistance and guidance provided by the other
members of my committee. Dr. Robert C. Ablin and Dr.
Frank A. Hudson, are also appreciated.
I am especially grateful to Dr. Dale W. Zinn who
served as my graduate committee chairman during the eairly
part of my graduate studies. Appreciation is also ex
pressed to Dr. Charles T. Gaskins whose friendship, guid
ance and assistance with the statistical analysis were
most helpful.
11
v_
TABLE OF CONTENTS
ACKNOWLEDGEMENTS ii
ABSTRACT V
LIST OF TABLES vii
LIST OF FIGURES viii
I. INTRODUCTION 1
II. REVIEW OF LITERATURE 2
III. RESULTS AND DISCUSSION 5
Summary 5
Introduction 6
Methods and Materials 7
Results and Discussion 8
On Test Weight 11
Weight Gains 11
Sale Price 12
Weight Effects 12
Fat Thickness 14
Height and Length Measurements 18
Selected Correlations 22
Length of Test Period 2 4
LITERATURE CITED 27
111
•T.- VTT:
APPENDIX TABLES
A. Composition of the Bull Test Diets 29
B. Components of Indices 30
C. Distribution of Bulls within Year and Breed by Fat Thickness over the Ribeye 31
D. Least Squares Means for Body Length and Height of Bulls On and Off Test - 1971 33
IV
ABSTRACT
Selected traits were analyzed for 708 bulls tested at
the Texas Tech University Center at Amarillo from 1967 to
1975. The trend for these traits indicated little change
in ADG and weight per day of age (WDA) over the years.
Weight on test was influenced by age on test (r = .66).
Younger bulls either maintained or increased their WDA
during the test period.
ADG and WDA were increased slightly by the introduction
of the larger, later-maturing European breeds and their
crosses. The larger breeds also exhibited less fat thick
ness over the ribeye.
A more detailed analysis of the 80 bulls tested in
1970-71 showed that Angus and Hereford bulls fattened at a
greater rate than the Simmental crosses. Length and height
measurements revealed that the longer and taller bulls were
heavier both on and off test and were less fat.
The bull's index was most highly related to sale price
(r = .62) and was followed by off test weight (r = .54) and
ADG (r = .47). Off test age and fat thickness over the rib
eye influenced buying decisions very little. Because the
index was heavily influenced by weight and gain, buyers
obviously selected the larger, faster-gaining bulls.
^
Simple correlation coefficients between variables at
the 112- and 140-day test periods were .97 for weight, .89
for total weight gain and .95 for fat thickness. These
results indicate that the 140-day test period could be
shortened to 112 days with only a small loss of information.
VI
y " ' ^
LIST OF TABLES
1. Number of Bulls by Breeds by Years 9
2. Least Squares Means for the Effects of Year on Selected Traits 10
3. Simple Correlation Coefficients for Height and Length Measurem.ents with Selected Traits 21
tween selected traits. Sale price was most highly associated
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with index (r = .62) and 140-day weight (r = .54). ADG and
grade accounted for 22 and 18%, respectively, of the vari
ance in sale price. Fat thickness, off test age and 205-
day adjusted weaning weight were associated with less than
3% of the variation in sale price. However, Marlowe and
Marlowe (1965). and Swaim et al. (1966) found higher associa
tions for both fat thickness and off test age with sale price
Buyers of bulls apparently considered the index, final
weight, ADG and grade more than the other traits when
selecting bulls. Off test age and fat thickness had very
little influence on sale price. Gain, rather than composi
tion of gain, obviously was more important to the buyers.
Index was most highly associated with ADG (r = .76).
This association is due to the fact that the indexes used
over the years emphasized measures of weight—either WDA,
ADG or 365-day adjusted yearling weight (Appendix Table B).
Grade, which was a subjective composite measure given by
three persons, was positively associated with index (r =
.70) but negatively associated with fat thickness (r = -.57),
Therefore, the graders tended to give the fatter bulls a
lower grade. The heavier and older bulls tended to be
fatter coming off test.
Length of Test Period
Simple correlation coefficients between final weight
of total gain while on test with weight or total gain after
25
each 28-day weigh period are contained in Table 5. The cor
relations of weight at each weigh period with the 140-day
TABLE 5- SIMPLE CORRELATION COEFFICIENTS BETWEEN FINAL WEIGHT OR TOTAL GAIN WHILE ON TEST WITH
WEIGHT OR TOTAL GAIN AT EACH 28-DAY WEIGH PERIOD^
Weigh period, days
Off test weight
.84**
.89**
.92**
.96**
.97**
Total gain after 140 days
0
28
56
84
112
46**
82**
89**
N=7 08.
Value for 28 days was not calculated.
* * P<.01.
weight were significant (P<.01). On test weight accounted
for 71% of the variation in final weight; this percentage
increased throughout the test: 79% at 28 days, 85% at 56
days, 92% at 84 days, and 94% at 112 days. The correla
tions indicate that final weight could be predicted at each
interval during the test with reasonable accuracy and that
the accuracy increased with each successive weigh period.
The correlations between weight gains were not as high as
the correlations between weights at the weigh periods.
Twenty-one percent of the variation in total gain during
26
140 days was associated with gain at 56 days, but the rela
tionship increased greatly to 67% at 84 days and 79% at 112
days.
In the 1971 study, the simple correlation of fat thick
ness at 112 days with fat thickness at 140 days was .94.
Therefore, with these high correlations, the test could be
concluded before 14 0 days with only a small loss of produc
tion information. If the tests had been concluded after
112 days, 21% of the variation in total gain, 12% of the
variation in fat thickness (1971 data only) and 8% of the
variation in live weight at 140 days would have been un
explained. Concluding the test at 84 days would have
resulted in a further reduction of 12% in 140-day total
gain predictability, only a 2% reduction in 140-day weight
predictability, and a 17% reduction in 140-day fat thick
ness predictability.
These data suggest that feeding tests should be termi
nated at 112 days. Relatively small losses in information
occur when the standard 14 0-day test is reduced in length
by 28 days. Additionally, bull testing would become less
expensive and the bulls would become less fat, possibly
causing fewer reproductive problems. The shorter feeding
period would more nearly match that presently used with
steers, which would allow more realistic comparisons of
steer and bull half-sib data.
LITERATURE CITED
Black, W. H., Bradford Knapp, Jr. and A. C. Cook. 1936. Correlation of body measurement of slaughter steers with rate and efficiency of gain and with certain characteristics. J. Agr. Res. 56:465.
Carter, R. C. and C. M. Kincaid. 1959. Estimates of genetic and phenotypic parameters in beef cattle. J. Anim. Sci. 18:331.
Cundiff, L. A., Doyle Chambers, D. F. Stephens and R. L. Willham. 1964. Genetic analysis of some growth and carcass traits in beef cattle. J. Anim. Sci. 23:1133.
Grizzle, J. E. and C. M. Kincaid. 1954. The relationship between body weight, daily gain, and efficiency of feed utilization in beef cattle. J. Anim. Sci. 13: 959 (Abstr.).
Harvey, Walter R. 1960. Least Squares Analysis of Data with Unequal Subclass Numbers. U.S.D.A., A.R.S. Bull. 20-8.
Hazel, L. N. and Jay L. Lush. 1942. The efficiency of three methods of selection. J. Hered. 33:393.
Knapp, Bradford, Jr., A. L. Baker, J. R. Quesenberry and R. T. Clark. 1941. Record of performance in Hereford cattle. Mont. Agr. Exp. Sta. Bull. 397.
Kohli, M. L., A. C. Cook and W. M. Dawson. 1951. Relations between some body measurements and certain performance characters in milking Shorthorn steers. J. Anim. Sci. 10:352.
Marlowe, G. A. and T. J. Marlowe. 1965. Some factors that influence the sale price of Virginia performance tested bulls. Livestock Research, 1964-65 Progress Report. Va. Agr. Exp. Sta.
Schalles, R. R. and T. J. Marlowe. 1967. Factors affecting test performance of beef bulls. J. Anim. Sci. 26:21.
Shelby, C. E., R. T. Clark and R. R. Woodward. 1955. The heritability of some economic characteristics of beef cattle. J. Anim. Sci. 14:372.
27
o 8
Shelby, C. E., W. R. Harvey, R. T. Clark, J. R. Quesenberry and R. R. Woodward. 1963. Estimates of phenotypic and genetic parameters in ten years of Miles City R.O.P. steer data. J. Anim. Sci. 22:346.
Stanley, E. B. and Ralph McCall. 1945. A study of performance in Hereford cattle. Ariz. Agr. Exp. Sta. Tech. Bull. 109.
Swaim, J. R. ill, c. B. Ramsey and J. B. McLaren. 1966. Somacope estimates of fatness and muscling of bulls at Ames Plantation. Tennessee Farm and Home Science Progress Report No. 58.
Swiger, L. A., K. E. Gregory, R. M. Koch, W. W. Rowden, V. H. Arthaud and J. E. Ingalls. 1963. Evaluating post-weaning gain of beef calves. J. Anim. Sci. 22: 514.
Warwick, Bruce L. and T. C. Cartwright. 1955. Heritability of rate of gain in young growing beef cattle. J. Anim. Sci. 14:363.
Wilson, L. L., C. A. Denkel, D- E. Ray and J. A. Minyard. 1963. Beef cattle selection indexes involving conformation and weight. J. Anim. Sci. 22:1086.
Winters, Lawrence M. and Harry McMahon. 1933. Efficiency variations in steers. Minn. Agr. Exp. Sta. Tech. Bull. 94.
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APPENDIX TABLE D. LEAST SQUARES MEANS FOR BODY LENGTH AND HEIGHT OF BULLS ON AND OFF