Group Title: Animal Science Department mimeograph series
Title: A Comparison of the efficiency of utilization of dietary protein by steers and bulls
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 Material Information
Title: A Comparison of the efficiency of utilization of dietary protein by steers and bulls
Series Title: Animal Science Department mimeograph series - Florida Agricultural Experiment Station ; AN65-10
Physical Description: 12 p. : ; 28 cm.
Language: English
Creator: Hentges, J. F ( James Franklin ), 1925-
Champagne, J. R.
Carpenter, J. W.
Palmer, A. Z.
Moore, J. E.
Publisher: Florida Agricultural Experiment Station
Place of Publication: Gainesville, Fla.
Publication Date: January, 1965
Copyright Date: 1965
 Subjects
Subject: Beef cattle -- Feeding and feeds -- Florida   ( lcsh )
Bulls -- Feeding and feeds -- Florida   ( lcsh )
Proteins in animal nutrition   ( lcsh )
Feed utilization efficiency -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: J.F. Hentges, Jr. ... et al..
Bibliography: Includes bibliographical references (p. 11-12).
General Note: Caption title.
General Note: "January, 1965."
 Record Information
Bibliographic ID: UF00072963
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 77551032

Full Text
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Animal


"-Mimec
1/: AN 6
I fCpp


Science Department
raph Series No.
10 .


Florida Agricultural
Experiment Station
Gainesville, Florida
January, 1965


A COMPARISON OF THE EFFICIENCY OF UTILIZATION OF
S. Y STEERS AND BULLS

J. F..Hentges, Jr., J. R. Champagne, J. W.
A. Z. Palmer and J. E. Moore


DIETARY PROTEIN


Carpenter,


The fattening of bulls instead of steers in the future has been predic-
ted (Champagne, 1964) as one means of achieving a more efficient conversion
of feed nutrients to-leaner carcasses.

Research on the comparative utilization ofdietary protein by .equivalent
bulls and steers has been reported only for European breeds of dual purpose
cattle (Richter et al. 1959 a,b; Richter, 1961; Homb, 1958; Witt, 1960).

Bogart et al. (1963) reported that blood levels of.amino and urea nitrogen
could be used to, determine the efficiency of dietary nitrogen utilization.
Blood urea nitrogen levels in _ruminants have been reported ,to be influenced by
dietary protein level (Schmidt-Nieisen et al. 1958; Preston et al. 1961).


The.objective of this experiment was to
efficiency of utilization of dietary protein
gain, certain nitrogenous blood constituents
to lean tissue.


compare bulls and steers for
by studying differences in daily.
and conversion of feed nutrients


Experimental Procedure,.,

The experimental animals were sixty male Hereford calves sired by. the
same bull within a 21-day period. They.. were divided into groups of 20 early
castrates (castrated at 1-60 days of age), 20 late.castrates (castrated at,
210-255 days of age) and 20 bulls. Half of each group was fed a control diet
(C) calculated to provide recommended requirements of.nutrients (NRC, 1958)
.while the other half was fed a diet (HP) with the same ingredients but a higher
content of crude protein. The composition of the diets is shown in table 1.
Data are presented for an 84-day period which represents the second phase of .
a research project reported elsewhere by Champagne (1964).

On days 47 and 75 of the 84-day period, venous blood samples were drawn
into citrated tubes after a 14-hour fast. All samples were centrifuged and
stored at 0F. within:one and one-half hours after sampling. Plasma.urea
and ammonia nitrogen determinations were conducted approximately 60 days later
by the methods Idescribed by Conway (1957) with modifications of O'brink (1955).
All determinations were conducted in duplicate and results expressed in mg./
100 .ml.


og
5-;











Correlation coefficients were obtained by a stepwise multiple regression
analysis on an IBM 709 computer.

Results and Discussion

Data for weight gains, efficiency of feed utilization and protein intake
are summarized in tables 2 and 3. Bulls gained faster than steers on both
dietary protein levels. Bulls and early castrates fed the diet providing the
recommended protein level (C) gained faster than their respective HP groups,
the differences being 0.33 lb. per day for bulls and 0.12 lb. per day for
early castrate steers.

Tha daily intake of crude protein was much larger with the HP diet, the
average difference between animals fed the HP and C diets being 0.53, 0.76
and 0.43 pound, respectively for early castrates, late castrates and bulls.
The larger intake of protein in the HP diet was not reflected in faster
gains.

The efficiency of utilization of dietary protein, as shown by differences
in intake of crude protein per pound of weight gain was consistently superior
with the C diet, the differences being 0.26, 0.23 and 0.28 pound between the
two levels of protein fed to early castrates, late castrates and.bulls respec-
tively. Although bulls consumed more crude protein per day than steers, the
difference being 0.2 to 0.3 lb. for C and none to 0.1 lb. for HP groups; the
differences in quantity of protein consumed per pound of weight gain were
very small. This reflected both a larger daily feed intake and a larger
daily weight gain by bulls.

Blood urea nitrogen values of all groups fed C were lower than for their
respective HP groups (table 4). The dietary protein level was shown by
Preston et al. (1961) to influence blood urea nitrogen concentrations in
yearling steers. At the 47th day, bulls fed C had 6.2 and 4.8 mg./100 ml.
less urea nitrogen than early and late castrates, respectively. At the
75th day, these differences were 0.35 and 0.08 mg. Fast gaining animals have
been reported to have lower blood urea nitrogen concentrations than slow
gaining animals fed the same diet (Bogart et al. 1963).

At the 45th day, the blood ammonia concentrations of early and late cas-
trates fed HP were 0.16 and 0.17 mg./100 ml. higher than for their respective
C groups. Likewise, bulls fed C had concentrations 0.01 mg./100 ml. higher
than for their HP group. At the 75th day, blood ammonia concentrations be-
tween protein groups were found to be opposite those obtained on the 45th day.
Early and late castrates fed C had 0.07 and 0.06 mg./100 ml. more blood
ammonia nitrogen than those fed HP while bulls fed HP had concentrations 0.19
mg./100 ml. higher than those for bulls fed C. The inconsistency of the blood
ammonia data may partially be due to the inherent weakness of the titration
method used to detect low concentrations of ammonia. The level of blood urea
nitrogen appears to indicate nitrogen wastage better than the level of blood
ammonia nitrogen. The use of blood urea nitrogen to determine protein utili-
zation in ruminants has been reported byLewis (1956).


- 2 -









-3-


Because bulls fed C gained 0.33 pound per day faster and had.lower
(6.72 and 2.65 mg./100 ml.) blood urea nitrogen values than bulls fed HP
at both bleedings, it is apparent that the 11.0% level of crude protein in
the C diet was nearer the optimum than the 14.0% level in the HP diet.

Bogart et al. (1963),interpreted:their data to indicate that faster
gaining animals may have a higher protein requirement; however, they did not
elaborate on whether the increased requirement would be on a "pound per day"
or "percentage of the diet" basis. It can be postulated that the faster growth
rate by bulls, as compared to steers, would necessitate a larger daily re-
quirement for protein on the cellular level; however, their apparently more
efficient utilization of the nitrogen in their dietary crude protein permitted
them to obtain an adequate quantity of protein from diets containing the same
percentage of crude protein as recommended for steers. Because the N.R.C.
(1958) recommends higher percentages of crude protein in bull than in steer
diets, a change in this publication may be warranted when further research
is completed.

The carcasses were broken-down into separable portions (table 5) as
described by Champagne (1964). Liveweights at the beginning of phase I were
nearly equal (table 2); therefore, it was assumed that the percent of body
lean and fat were nearly equal among groups. It was estimated that the bulls
fed C gained 22 lb. more lean with an efficiency of 0.28 lb. less dietary pro-
tein per lb. of body weight gain than bulls fed HP. Although the bulls fed C
gained more total pounds of lean, they had 1.0% less carcass lean because of
a higher percentage of fat in their carcasses. This may have been caused by
the wider protein:calorie ratio in the C diet. Bulls yielded 3.3 to 5.6% more
lean than either group of steers. This confirms previous reports by Klosterman
et al. (1954) and Nichols et al. (1964).

All groups fed C required less dietary protein per pound of gain in
carcass lean than groups fed HP, the difference being 0.11, 0.46 and 0.25
pound respectively for early castrates, late castrates and bulls. These data
suggest that the 11.0% crude protein level in diet C resulted in a more ef-
ficient conversion of dietary protein to lean tissue than the 14.0% level of
crude protein in the HP diet.

Bulls required from 0.2 to 0.35 lb. less dietary protein per pound of
gain in carcass lean than early and late castrate steers, respectively. This
finding lends strength to the prediction of Champagne (1964) that the fatten-
ing of bulls for slaughter will become widespread in the future.

Table 6 shows that there were no differences between groups fed the two
dietary protein levels for percentage composition of moisture, ether extract
and protein in the Longissimus dorsi muscle.












Correlation coefficients were low (table 7) among blood urea nitrogen
levels, blood ammonia nitrogen levels and body 'weights taken 56 days prior
to bleeding. Bogart et al. (1963) reported significant correlations between
blood urea nitrogen and daiily gain of -.29 and -.30 respectively for 500 and
800 lb. males and female cattle. This study with bulls and steers gave lower
correlations of -.01 and -.04 respectively for the first and second bleedings.
Blood ammonia nitrogen content was correlated (P -.05) with daily gain (-.30).
Bogart et al. (1963) did not study blo6d ammonia levels in relation to daily'
gain.

Summary

Two levels of dietary protein,, -recommended and high, were studied for
effect on weight gain, blood nitrogen content and efficiency of protein
utilization by bulls and steers.

Bulls fed a diet containing 11.0% crude protein gained in liveweight
more rapidly and converted dietary protein to carcass lean more efficiently
than bulls fed a diet containing 14.0% crude protein.

Apparently, the level of dietary protein recommended for steers is ade-
quate for bulls in spite of the lower requirement by bulls for feed per pound
of weight gain. This may be explained by the more efficient utilization of
dietary protein for weight gain by bulls.

Groups within diets which had relatively low blood urea nitrogen levels
and relatively high daily gains tended to have more pounds of carcass lean.

Correlations among daily liveweight gain, blood urea nitrogen level and
blood ammonia nitrogen level were low, -.01 to -.30.








- 5 -


TABLE 1. COMPOSITION OF DIETS


Ingredients


Corn meal, yellow
Corncobs, ground
Cane molasses -
Cottonseed meal, 41%
Pelleted premix, 50- %
Total


High protein

58
15
10.
9

100


Dietst/
S Control

65
16
S...... 10

S" 9
100


1/ Composition of premix:


Lb.


25
20
10
-5--- '-
12
17
5
0.8
(33.3 gm.)
5
99.8


Ingredient

Alfalfa meal, dehy., 17%
Cottonseed meal, 41%
Soybean meal, 44%
---.Peanut-meal,. o.p., 50%
Urea, 262%
Mineral mixture
Sodium bicarbonate
Aurofac 10
Vitamins A and D premix
Cane feeding molasses


2/ Crude protein content averaged 14% for "high protein" and 11% for
control diet.










-6-


TABLE 2. COMPARATIVE EFFICIENCY OF UTILIZATION OF DIETS BY BULLS AND
STEERS FED TWO DIETARY'PROTEIN LEVELS


Control diet High protein diet
Early Late Early Late
castrates castrates Bulls castrates castrates Bulls


Total feed/lb.
gain, lb.17 7.62 8..22 6.55 8.02 8.10 7.26

Conc./lb. gain, Ib. 7.02 7.41 ..6.03 7.29... 7.35 6.55

Hay/lb. gain, lb. 0.60 0.81 0.52 0.73 0.75 0.71


1/ Air-dry weight basis.









-7-


TABLE 3. AVERAGE WEIGHT GAINS
S GROUPS FED CONTROL AND


AND PROTEIN INTAKE OF CATTLE
HIGH PROTEIN DIETS/


Control diet High protein diet
Early Late Early Late
castrates castrates Bulls castrates castrates Bulls


No. of animals 10 10 10 10 10 10

Av. initial wt.
Phase I, lb. 430.1 422.4 428.6 436.1 424.4 427.4

Av. initial wt., lb. 648.9 633.5 707.2 631.2 624.1 684.1
Av. final wt., lb. 868.4 818.6 948.4 .840.0 828.2 897.6
Av. da. gain, lb. 2.61 .2.20. 2.87 2.49 2.43 2.54

Protein intake/
day, lb. 2.07 1.96 2.27 2.60 2.72 2.70
Protein intake/lb.
gain, lb. 0.79 0.89 0.79 1.05 1.12 1.07


1/ Average initial and final weights were shrunk 3%.











- 8-


TABLE 4. AVERAGE BLOOD UREA AND AMMONIA NITROGEN CONCENTRATIONS OF CATTLE
GROUPS FED CONTROL AND HIGH PROTEIN DIETS/


Control diet High protein diet
Early Late Early Late
castrates castrates Bulls castrates castrates Bulls


No. of animals 10 10 10 10 10 10

First bleeding:
NH3-N, mg./l00 ml. 0.74 0.66 0.71 0.90 0.83 0.70
Urea-N, mg./l00 ml. 32.81 31.37 26.61 41.29 35.29 33.33

Second bleeding:
NH3-N, rg./100 ml. 0.57 0.70 0.53 0.50 0.64 0.72
Urea-N, mg./100 ml. 27.04 26.77 26.69 38.12 30.13 28.34


1/ 47th and 75th day of feeding period for the first and second bleeding, respectively.












TABLE 5. SUMMARY OF DATA FOR SEPARABLE PORTIONS OF CARCASSES FROM
GROUPS FED CONTROL AND HIGH PROTEIN DIETS


Control diet High protein diet
Early Late Early Late
castrates castrates Bulls castrates castrates Bulls


No. of animals 10 10 10 10 10 10

Av. chilled carcass wt., lb. 515 491 583 498 493 544
Av. carcass lean, % 69.2 70.5 73.8 69.2 69.3 74.8
Av. carcass fat, % 16.1 13.7 12.2 16.3 14.6 10.1

Av. carcass lean, lb. 357 346 430 345 342 407
Av. carcass fat, lb. 83 67 71 81 72 55

Estimated initial carcass lean, Ib.I/ 193 189 192 195 190 191
Estimated gain of carcass lean, lb. 164 157 238 150 152 216

Protein consumed per lb. of gain in
carcass lean, lb. 1.07 1.04 0.8 1.18 1.5 1.05


I/ Based on the following assumptions:


dressing %, 56%; % lean, 80%.









- 10


TABLE 6. EFFECT OF DIETARY PROTEIN LEVEL ON THE CHEMICAL
COMPOSITION OF THE LONGISSIMUS DORSI MUSCLE



Diet
Control diet High protein diet


Moisture, % 73.68 73.67

Ether extract, % 2. 49 '2.34

Crude protein, % 21.90 21.82


TABLE 7. CORRELATION


COEFFICIENTS BETWEEN
AND n\ILY GAIN


CERTAIN BLOOD CONSTITUENTS


SDaily gain N!3-N


First bleeding

NH -N -.13

Ure- N -.01 .20

Second bieediig

NH-N. -.30*

Urea N -.04 -.04


* P <.0S








- 11 -


Literature Cited

1. Bogart, R., F. R. Ampy, A. F. Anglemeir and W. K. Johnston, Jr. 1963.
Some physiological studies on growth and feed efficiency of beef
cattle. J. Animal Sci. 22:993.

2. Champagne, J. R. 1964. Effect of age of castration and dietary protein
level on the feedlot performance and carcass characteristics of
bulls and steers. Masters Thesis. University of Florida, Gaines-
ville, Florida.

3. Conway, E. J. 1957. Microdiffusion Analysis and Volumetric Error (4th
edition). The MacMillan Co., New York.

4. Homb, T. 1958. Bullocks versus steers in beef production. Eighty-
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5. Klosterman, E. W., L. E. Kunkle, P. Gerlaugh and V. R. Cahill. 1954.
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carcass quality of beef calves. J. Animal Sci. 13:817.

6. Lewis, D. 1956. Blood urea concentration in relation to protein ut-
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7. Nichols, J. R., J. H. Ziegler, J. M. White, E. M. Kesler and J. L.
Watkins. 1964. Production and carcass characteristics of Holstein-
Friesian bulls and steers slaughtered at 800 or 1,000 pounds. J.
Dairy Sci. 47:179.

8. O'brink, K. J. 1955. A modified Conway unit for microdiffusion ana-
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9. Preston, R. L., L. H. Breur and G. B. Thompson. 1961. Blood urea in
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10. Richter, K., K. L. Cranz and K. H. Schmidt. 1959. Mastversuche mit
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11. Richter, K., K. L. Cranz and K. H. Schmidt. 1959. Jungbullenmast mit
silage aus mais, gras und biertrebern. Zuchtungskunde. 31:308.

12. Richter, K. 1961. Neure untersuchungsergebnisse zur jungrindermast.
Zuchtungskunde. 33:337.









- 12 -


13. Schmidt-Nielsen, B., H. Osaki, H. V. Murdaugh, Jr. and
1958. Renal regulation of urea excretion in sheep.
194:221.
0'~ ~~~~ ..


R. O'Dell.
Am. J. Physiol.


14. Witt, M. 1960. Unpublished data. Personal correspondence.
Planck Institute, Mariensee, Trenthorst, West Germany.








































JFH:jf
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1/21/65
An. Sci.


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