F. ( 1 r,9-6
Department of Animal Science
Mimeograph Series No. AN69-6
THE EFFECT OF DIETHYLSTILBESTROL AND METHYLTEST(
AT TWO PROTEIN LEVELS ON THE- FEEDLOT PERFORM
AND CARCASS QUALITY OF FINISHING SWINE 1j
E. W. Lucas, H. D. Wallace, 'A. Z.-Palmer,
S ,TE 5 ... i ,,r |..
SVMAY 2 1969
J. W. Carpenter and G. E. Combs 2/
.. I.fA.S. Univ. of Florida
Reports from:the Florida Station (1, 2, 3, 4, 5, 6, 7, 8) Fndiate that
meat type hogs can benefit from increased protein allowances. Some work (6, 7)
also indicates that improved carcass leanness results when a dietary combination
of the sex hormones diethylstilbestrol and methyltestosterone is fed. However
an undesirable aroma and taste was imparted to the meat by this hormone treatment.
The following experiment was designed tb study further the effects of dietary
protein level and hormone supplementation on finishing swine. Included in the
investigation was a study of the interactions between sex, protein level, and hor-
mone supplementation as they affect feedlot performance, carcass qualities and
acceptability of the pork.:
Seventy two crossbred pigs (Duroc-Landrace x Hampshire) were selected for
the experiment. The average initial weight was 99.1 pounds. Equal numbers of
barrows and gilts were used. The pigs were group fed in lots of 18 from self-
feeders in concrete confinement pens. Two protein levels (12 and 16%) were
studied. The 12% diet was chosen to be adequate or near adequate for feedlot
performanc..but probably inadequate in terms of maximum lean tissue production.
The 16%jdiert.ws selected to provide a generous level of protein so that the
hormone treatment would be given opportunity to manifest an optimum influence
on carcass leanness. The diets used are presented in Table 1. -The experimen-
tal design is described in Table 2.,,.
Hormone treatment was discontinued 72 hrs. prior to slaughter and all viscera
from treated animals were discarded at slaughter. The animals were slaughtered
when average weight reached 211 pounds. The pigs were slaughtered and dressed
packer style for carcass study. Carcass weights and measurements were taken
after the carcasses had been chilled for 48 hours at 34-36 degrees F. Length
of carcass was obtained by a measurement from the anterior edge'of the aitch bone
(pelvis) to the anterior edge of the first rib. Backfat thickness was calculated
as an average of measurements taken at the first rib, last rib and last lumbar ver-
tebra. A tracing was made of the perimeter of the longi'simus dorsi muscle (loin
eye) exposed by cutting the loin perpendicular to the vertebral column equidistant
between the tenth and eleventh ribs. The area of the loin eye muscle was then de-
termined by use of a compensating polar planimeter. The degree of marbling was
recorded based on the following numerical code: slight plus indicated by 9; small
minus, 10; small, 11; small plus,'12; modest minus, 13; modest, 14; modest plus,15;
moderate minus, 16. The carcasses were broken down by a standard procedure (Recip-
rocal Meat Conference, 1951).
1/ Supported in part by a grant from Eli Lilly and Company, Greenfield, Indiana.
2/ Lucas, graduate assistant; Wallace, Animal Nutritionist; Palmer, Meat Scientist;
Carpenter, Associate Meat Scientist and Combs, Animal Nutriticaist, Department
cf Animal Science.
Blade loin roasts were wrapped for freezing, frozen at -600 F., and stored at
00 F. Prior to cooking the roasts were defrosted overnight at 500 F. The roasts
were cooked in covered Pyrex ovenware in a preheated 350 F. oven for 30-40 minutes
per pound to an internal temperature of 1700 + o5 F. Aroma and flavor were deter-
mined by a trained eight member panel with degree of sex odor and flavor being the
only palatability factors considered; panelists scored degree of undesirable odor
and flavor on the following scale: 1 designated none; 2, slight; 3, moderate;
4, strong. Aroma was evaluated on the hot roasts by lifting the lids of the oven-
ware containers to allow rising vapors to be tested. Each panelist sliced a
portion of each roast for flavor testing to assure that all testing would be on
Ingredient Protein Level, %
12 12 16 16
Ground Yellow Corn 89.25 89.25 79.00 79.00
Soybean Oilmeal (50%) 7.70 7.70 17.95 17.95
Defluorinated Phosphate 1.80 1.80 1.80 1.80
Ground Limestone 0.50 0.50 0.50 0.50
Iodized Salt 0.50 0.50 0.50 0.50
Trace Mineral Premixa 0.05 0.05 0.05 0.05
Vitamin Premix (Merck 1231)b 0.10 0.10 0.10 0.10
Vitamin Premix (Merck B12-20)c 0.05 0.05 0.05 0.05
Tylan Premixd 0.05 ---- 0.05
Bestron Premixe ---- 0.05 ---- 0.05
a Contained 11% calcium, 10% manganese, 10% iron, 10% zinc, 1% copper,
0.3% iodine and 0.1% cobalt.
b Contained 8,000, 14,720, 36,000 and 40,000 mg. per lb., respectively,
of riboflavin, pantothenic acid, niacin and choline chloride.
c Contained a minimum of 20 mg. B12 per pound.
d Contained 10 gm. tylosin per lb. and was added to the diets not
supplemented with Bestron so as to equalize tylosin fortification
for all diets.
e Contained 2 gm. diethylstilbestrol and 2 gm. methyltestosterone
and 10 gm. tylosin per lb.
Comparison Protein Level
12 12 16 16
Number of Barrows 9 9 9 9
Number of Gilts 9 9 9 9
Hormone Supplementation 1 lb/ton none 1 Ib/ton none
Results and Discussion
A summary of results is presented in Table 3.
Feedlot Performance Barrows and gilts were fed together so no observations were
made concerning the effect of sex on feed intake or efficiency of feed conversion.
Since the pigs were group fed, no analysis of variance was performed on the feed
data. Pigs fed the 12% protein diet ate markedly more feed than those fed the
16% protein ration. Hormone supplementation depressed feed consumption. Pigs
fed the higher protein level gained more efficiently than those on the lower pro-
tein level. Hormone supplementation did not appear to affect feed efficiency in
this trial. Although not significant, there was a trend toward increased daily
gains for pigs fed the low protein level, pigs not supplemented with hormone, and
for barrows. Hormone supplementation appeared to depress rate of gain for pigs
fed the low protein diet but did not affect gains of pigs on the higher level of
Carcass Characteristics Hormone supplementation reduced dressing percent sig-
nificantly (P < .01). The full explanation for this is not readily apparent but
is probably in part related to differences in finish. Backfat thickness was
significantly reduced (P < .05) by the higher protein level and also significantly
reduced (P < .01) by hormone supplementation. This latter effect was much more
pronounced in barrows than in gilts. Barrows had more backfat than gilts. Carcass
length did not appear to be affected by sex, level of dietary protein, or hormone
supplementation. There were no significant effects noted due to any of the treat-
ments on loin eye area, although gilts tended to have larger loin eyes than barrows
and there was a trend toward larger loin eyes in pigs fed the 16% protein diet com-
pared to those consuming the 12% protein diet. The yield of the four lean primal
cuts (loin, ham, picnic shoulder and Boston butt) was significantly increased by
hormone supplementation (P < .05) and also significantly higher (P < .05) in pigs
fed the higher level of protein when compared to the pigs fed the lower level of
protein. There was a significant interaction (P < .05) between sex and hormone
supplementation for % four lean cuts. Hormone treatment improved leanness more
in barrows than gilts. Loin eye marbling score was not significantly affected by
sex or hormone supplementation. Pigs fed the 16% protein diet had significantly
(P < .05) less marbling in the loin eye than pigs consuming the 12% protein diet.
Loin Roast Aroma and Flavor A highly significant (P < .01) increase in loin
roast aroma and flavor scores was observed due to hormone. This same trend was
observed in previous trials (7, 8) and the undesirable odor and flavor of the meat
was probably caused by the methyltestosterone in the hormone supplement. No effect
on meat flavor or odor was noted due to sex or protein level.
Seventy two pigs were fed from an average of 99 pounds to an average of 211
pounds in an experiment designed to evaluate the effects of methyltestosterone
and diethylstilbestrol at two protein levels (12% and 16% crude protein) on feed-
lot performance, carcass quality and pork acceptability.
Improved feed efficiency, decreased feed consumption, decreased backfat
thickness, increased yield of four lean cuts, and increased carcass leanness
were noted in pigs fed the 16% protein diet when compared to those fed a 12%
protein diet. However, this result should not be construed to mean that a 16%
protein diet is optimum or to be recommended for finishing swine. This level is
undoubtedly higher than necessary.
Table 3. Influence of dietary protein level, hormone supplementation and sex on feedlot
performance, carcass characteristics and pork acceptability.
Main experimental variables Protein level % Hormonea Sex
Comparison 12 16 + Barrows Gilts
Number of animals 36 36 36 36 36 36
Initial wt., lb. 99.2 99.1 99.2 99.1 99.8 98.5
Final wt., lb. 212.8 208.5 212.4 208.9 212.3 209.0
Daily feed intake, lb. 6.17 5.68 6.04 5.81 -
Daily gain, lb. 1.72 1.66 1.72 1.66 1.70 1.67
Feed per unit gain, lb. 3.59 3.43 3.52 3.50 -
Dressing % 71.24 71.74 72.41 70.57** 71.61 71.37
Backfat thickness, in. 1.47 1.36* 1.48 1.34** 1.44 1.39
Carcass length, in. 30.75 30.74 30.62 30.87 30.78 30.73
Loin eye area, sq. in. 3.84 4.02 3.97 3.89 3.84 4.02
% four lean cuts 48.49 49.74* 48.42 49.81* 48.63 49.59
Loin eye marbling score 15.2 12.0* 13.2 13.9 14.3 12.9
Loin roast aroma score 1.23 1.26 1.14 1.33** 1.26 1.23
Loin roast flavor score 1.10 1.12 1.04 1.18** 1.13 1.09
a Bestron was added at a
per ton of feed.
* P < .05,.** P < .01.
level to provide 2 gm. diethylstilbestrol and 2 gm. methyltestosterone
Hormone supplementation improved feed efficiency, decreased daily gain,
decreased backfat thickness, increased yield of 4 lean cuts, and was observed
to impart an undesirable flavor and odor to the meat of some pigs. As in two
previous tests this latter observation was highly significant (P < .01) and is
considered to be a very serious problem.
No significant differences due to sex were observed. However, the usual
trends were apparent between carcasses of barrows and gilts.
1. Wallace, H. D., M. E. Palmer, A. Z. Palmer, J. W. Carpenter and G. E. Combs.
1963. The influence of protein level on feedlot performance and carcass
characteristics of barrows and gilts. Fla. Animal Sci. Mimeo. Series AN64-7.
2. Wallace, H. D., A. Z. Palmer, J. W. Carpenter, Ghazi Taki and G. E. Combs.
1964. The influence of protein level on feedlot performance and carcass
characteristics of barrows and gilts. Fla. Animal Sci. Mimeo. Series AN64-16.
3. Crum, R. C., Jr., H. D. Wallace, A. Z. Palmer, J. W. Carpenter and G. E. Combs.
1964. The influence of protein level on feedlot performance and carcass char-
acteristics of barrows and gilts. Fla. Animal Sci. Mimeo. Series AN65-3.
4. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1965. A
study of the relationship of feed restriction and dietary protein level in
finishing hogs. Fla. Animal Sci. Mimeo. Series AN65-9.
5. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1966. Feed
restriction of swine during the finishing period. Fla. Agr. Exp. Sta. Bul.
6. Wallace, H. D., L. A. Britt, J. W. Carpenter, A. Z. Palmer and G. E. Combs.
1966. Effects of dietary protein levels and amino acid supplementation on
the feedlot performance and carcass characteristics of growing-finishing
swine. Fla. Animal Sci. Mimeo. Series AN67-3.
7. Wallace, H. D., A. Z. Palmer, J. W. Carpenter, L. A. Britt, A. C. Warnick
and G. E. Combs. 1967. Influence of protein level and hormone supplemen-
tation during the finishing period on feedlot performance, carcass character-
istics and pork acceptability. Fla. Animal Sci. Mimeo. Series AN67-10.
8. Lucas, E. W., H. D. Wallace, A. Z. Palmer, J. W. Carpenter and G. E. Combs.
1968. The influence of sex, protein level, and hormone supplementation on
the feedlot performance and carcass characteristics of growing-finishing
swine. Fla. Animal Science Mimeo. Series AN69-5.