/,,. AN wi-S
Department of Animal Science Florida Agricultural
Mimeograph.Series No. AN69-5 Experiment Station
September,-1968 Gainesville, Florida
The Influence of Sex, Protein Level, an HUME LIBRAR
Hormone Supplementation on the Feedlot
Performance and Carcass Characteristic
of Growing-Finishing Swine / MAY 2 31969
E. W. Lucas, H. D. Wallace, A. Z. Palme
J. W. Carpenter and G. E. Combs 2/ l .AS.- Univ. of Florida
Recent experiments at the Florida Station (1, 2, 3, 4, 5,6, 7) have shown
the importance of protein nutrition in producing desirable pork carcasses. Re-
sults of these experiments indicate that perhaps recommended protein allowances
are not sufficient for optimum growth, performance, and carcass leanness in
modern meat-type hogs.
The experiment described here was designed to study further this phase of
swine nutrition. Factors under consideration were sex, dietary protein level,
and supplementation with a combination of the hormones diethylstilbestrol and
methyltestosterone. The response to each of the above-mentioned factors and the
interactions between them were included in the statistical analysis.
The study consisted of two parts. For the first part sixty crossbred pigs
of Duroc-Landrace x Hampshire breeding having initial weights ranging from
15-30 Ib. were segregated by sex into two lots (30 gilts and 30-barrows). Both
groups were self-fed in concrete confinement pens a 16% protein diet. The object
was to determine the relative performance of the two sexes during theiearly grow-
ing period. It is,well established that the sexes perform quite differently
during the finishing period and thus it was of interest to examine'the early
growth period in this regard. This part of the experiment was terminated when
the pigs reached an average weight of 124 lb. From the original 60 pigs, 48
were then selected for use in the second part of the study. These were individ-
ually fed in four treatment groups. Two dietary protein levels (12 and 14%) were
compared and the influence of feeding a combination of diethylstilbestrol and
methyltestosterone was studied.
Diet compositions and the experimental designs are presented in Tables 1
and 2 respectively.
Hormone treatment was discontinued 72 hrs..prior to slaughter and all viscera
from treated animals were discarded at slaughter. The animals were slaughtered on
an individual basis as,live weights reached the range of 245-255 pounds'. The final
average slaughter weight for all pigs was.248.2 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
1/ Supported in part by a grant from Eli Lilly & Co., Greenfield, Indiana.
2/ Lucas, Graduate Assistant; Wallace, Animal Nutritionist; Palmer, Meat
Scientist; Carpenter, Associate Meat Scientist and Combs, Animal Nutri-
vertebra. A tracing was made of the perimeter of the longissimus dors 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 determined by use of a compensating polar planimeter. The degree
of marbling was recorded based on the following numerical code: slight plus, 9;
small minus, 10; small, 11; small plus, 12; modest plus, 13; modest, 14; modest
plus, 15; moderate minus, 16. The carcasses were broken down by a standard pro-
cedure (Reciprocal Meat Conference, 1951).
Blade loin roasts were wrapped for freezing, frozen at -60o ., 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 35g F. oven for
30-40 minutes per pound to an internal temperature of,~1700 + 5 F. Aroma and
flavor were determined by a trained eight member panel with degree of sex odor
and flavor being the only palatability factors considered; panelists scored
degree of odor and flavor on the following scale: 1 designated none; 2, slight;
3, moderate; 4, strong. Aroma was evaluated on the hot rccsts by lifting the
lids of the ovenware containers to allow rising vapors to be tested. Each
panelist sliced a portion'of each roast for flavor testing to assure that all
testing wQuld be on warm meat.
Table Composition of Diets
Ingredient Crude Protein Level, %
16 14 14 12 12
Ground Yellow Corn 78.00 82.85 82.85 88.25 38.25
Soybean Oil Meal (50%) 17.95 13.10 13.10 7.70 7.70
Ground Limestone 0.50 0.50 0.50 0.50 0.50
Defluorinated Phosphate 1.80 1.80 1.80 1.80 1.80
Iodized Salt 0.50 0.50 0.50 0.50 0.50
Merck 1231 Vitamin Premixa 0.10 0.10 0.10 0.10 0.10
Merck B12-20 Vitamin Premixb 0.05 0.05 0.05 0.05 0.05
Vitamin A & D Premixc 1.00 1.00 1.00 1.00 1.00
Trace Mineral Premixd 0.05 0.05 0.05 0.05 0.05
Tylan Premixe 0.05 0.05 --0.05 ---
Bestron Premixf --- 0.05 ---- 0.05
Total 100.00 100.00 100.00 100.00 100.00
a Contained 8,000, 14,720, 36,000 and 40,000 mg. per lb., respectively, of
riboflavin,. pantothenic acid, niacin and choline chloride.
b ;Contained minimum of 20 mg. B12 per pound..
c Contained 4.6 gm. Vitamin A supplement (30,000 I.U./gm), .25 gm. Vitamin D
supplement (200,000 I.U./gm) and 449 gm. yellow corn per lb.
d Contained 11% calcium, 10% manganese, 10% iron, 10% zinc, 1% copper, 0.3%
iodine and .0.1% cobalt.
e Tylan premix contained 10 gm. tylosin per pound and was added to the diets
not supplemented with Bestron so as to equalize tylosin fortification for
f Bestron contained 2 gm. diethylstilbestrol and 2 gm. methyltestosterone and
10 gm. tyiosin per pound.
Table 2. Experimental Design
(PART I 22-124 lb. liveweight)
Dietary Protein Level, 7 16
Hormone Supplement none
Number of Barrows- 30
Number of Gilts 30
(PART II 120-248 lb. liveweight)
Dietary Protein Level,'% 12 12 14 14
Hormone Supplement 1 lb/ton none 1 Ib/ton none
Number of Barrows 6 6 '6 6
Number of Gilts 6 6 6 6
II iI ii-- i i i ii
Results and Discussion
The summary of feedlot performance and carcass data is presented in Tables
3 and 4.
Growing Phase (Part I)
From initial to 124 pounds the barrows consumed more feed and gained more
than gilts, although the difference was not significant. The feed efficiency
was nearly the same for barrows and gilts, slightlyifavoring the gilts.
Finishing Phase (Part II)
Daily Feed Intake Hormone significantly (P < .01) decreased daily feed
intake and this observation was much mOre pronounced in the barrows than in the
gilts. Barrows ate more than gilts, but the effect was not significant. The
pigs fed 127. protein ate more than pigs fed 147 protein, probably in an attempt
to increase their nitrogen and/or amino acid(s) intake.
Table 3. Influence of Sex on Feedlot Performance of Growing Pigs. (Part I)
,= ,H ,
Number of animals .
Average initial: wt, lb.
Average final wt., lb.
Average daily feed, lb.
- --- ---------
Table 4. Influence of dietary protein level, hormone supplementation and sex on feedlot performance,
carcass characteristics and pork acceptability. (Part II)
Main experimental variables Protein level, % Hormonea Sex
Comparison 12 14 + Barrows Gilts
i~~ ii ...i i ii ii i
Number of animals
Initial wt., lb.
Final wt., lb.
Daily feed intake, lb.
Daily gain, lb.
Feed per unit gain, lb.
Backfat thickness, in.
Carcass length, in.
Loin eye area, sq. in.
% 4 lean cuts
Loin eye marbling score
Loin roaat aroma score
Loin roast flavor score
a Bestron was added at
ton of feed.
* P < .05, ** P < .01.
a level to provide
2 gm. diethylstilbestrol and 2 gm. methyltestosterone per
- --r- -
Daily Gain During the finishing stage barrows gained significantly more than
gilts (P < .05). No significant differences dde to"protein level or hormone
supplementation were observed in daily gain. The hormone treatment appeared to
depress.gains for the barrows but not for the gilts.
Feed Efficiency A significant (P < .01) effect due to hormone was observed on
feed required.per unit gain. Pigs fed the hormone supplement were more efficient
than those fed the control diet. This improvement was greater with the 12% pro-
tein diet. There was essentially no difference between barrows and gilts'.~n'feed
efficiency. Pigs fed 147, crude protein required 3.67 pounds of feed: per p'iund of
gain as compared to 3.84 pounds of feed per pound of gain required for pigs fed
12% crude protein. This difference was not statistically significant.
Carcass Characteristics Dressing percent was higher for pigs not given hormone,
pigs fed the 14% protein diet and for barrows. Differences were not significant.
Backfat thickness was significantly (P < .05 ) reduced in pigs fed the hormone
supplement as compared to pigs consuming the basal diet. The hormone caused a
much greater reduction in backfat in barrows than gilts. This hormone-sex inter-
action effect was significant (P < .01). No marked effect on backfat thickness
due to sex was noted, and pigs fed the low protein diet had only slightly more
backfat than pigs fed the high protein diet. Carcass length was not affected by
sex or protein level in the diet, but was significantly (P < .01) increased by
the addition of hormone. Loin eye area was not significantly affected by sex,
protein level in the diet, or hormone supplementation, although there was a trend
toward larger loin eyes in hormone fed pigs, in gilts, and in pigs consuming the
high protein diet. The percent of the four lean cuts (ham, loin, picnic shoulder,
and Boston butt) was not significantly affected by sex or dietary protein, but
there was a trend toward a higher percent of four lean cuts in gilts and pigs fed
the higher level of protein. Hormone supplementation significantly (F < .05)
increased the percent of four lean cuts. This general improvement in leanness
due to hormone feeding was much more pronounced and consistent in barrows than in
gilts. Loin eye marbling score was significantly (P < .05) reduced by higher pro-
tein in the diet, and unaffected by sex or hormone.
Aroma and Flavor of Loin Roasts Since methyltestosterone, a male sex hormone,
was included in the hormone supplementation, the meat was checked for undesirable
odors and flavors. A previous experiment (7) showed that hormone supplementation
could .pi'oddce'this undesirable characteristic in meat of pigs. In this experiment,
meat odor and flavor were unaffected by sex or protein level. There was a signif-
icant (P < .01) effect due to hormone in both loin roast aroma and flavor. Hormone
supplementation tended to increase the degree of undesirable odor and flavor in
roasts. The off-flavor was observed in both gilts and barrows.
Sixty pigs were fed from 22 to 124 pounds in two equal lots segregated by
sex to determine if the performance was!similar:on similar diets during this
early growth period. Barrows gained slightly more and ate slightly more than
gilts. Efficiency was essentially the same for barrows and gilts.
From the initial two lots, 48 pigs were selected and individually fed diets
containing either 12 or 14 percent crude protein and with and without hormone
supplementation. The experimental period extended from 120 pounds to a slaughter
weight of approximately 248 pounds.
Pigs fed the higher level of protein (14%) gained faster and more efficiently
and had leaner, more desirable carcasses than pigs fed d.lower protein level (12%).
Hormone supplenieted pigs consumed less feed;, gained slightly slower, gained
more efficiently, and yielded leaner carcasses than pigs fed the control diets.
The desirable effect on carcass leanness was especially pronounced in barrows.
The hormone treatment imparted an undesirable odor and flavor to. the meat of
some pigs. This observation represents a serious problem and must be overcome
before such hormone treatment could be-considered feasible.
Barrows consumed more feed, gained faster, and had about the same efficiency
as gilts. The carcasses of the gilts were slightly more desirable from the stand-
point of lean cpt out..
1. Wallace, H. D., M. E. Palmer, A.;2. 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
characteristics 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 supple-
mentation during-the-finishing period on feedlot performance, carcass
characteristics and pork acceptability. Fla. Animal Sci. Mimeo. Series