- Department of Animal Science Florida Agricultural
Animal Science Research Report AL73-9 Experiment Station
Wr1November, 1973 Gainesville, Florida
INFLUENCE OF SEX AND LYSINE ON PERFORMANCE AND CARCASS
CHARACTERISTICS OF GROWING-FINISHING SWINE 1/
D. C. Creswell, H. D. Wallace G. E. Combs
and R. L. West
In recent years the need for adequate protein levels to sustain maximum
feedlot performance and particular y rdud 1 carcass characteristics
has been well established (1, 2, )
Consistent differences have len obl ede c~ en ba rows and gilts. Barrows
usually have a faster growth rate han gilts. Gilts, op te other hand, are more
i, u A v Unlv. of Floroa
efficient in feed conversion and ppdue- fiA s than barrows. There is
some evidence that gilts require a higher level of dietary protein than do barrows
for optimum performance and carcass development (5, 6, 7, 8). When grain and
protein supplement were offered separately, gilts consumed by choice a mixture
of higher protein content than did barrows (9). These results suggest that there
may be differences between barrows and gilts in their requirements for specific
The purpose of this experiment was to determine if any differences existed
in the response of barrows and gilts to various dietary levels of the amino acid
lysine. A low protein corn-soybean meal ration was used to achieve a low lysine
level. Additions of L-lysine monohydrochloride to this ration were used to
1/ The data presented in this paper were from swine unit experiment No. 228.
2/ Creswell, graduate assistant; Wallace and Combs, Animal Nutritionists, and
West, Assistant Meat Scientist, Department of Animal Science.
This public document was promulgated at an annual cost of
$80.00 or .08 cents per copy to inform county agricul-
tural directors, ranchers and growers of research results
in swine management and nutrition.
Department of Animal Science
Institute of Food and Agricultural Sciences
produce a medium and high level of lysine. The high level of lysine was calculated
to be equivalent to the lysine level present in a 17% protein corn-soybean meal
ration. A 17% protein corn-soybean meal ration was used as a positive control.
Ninety-six pigs were divided according to sex and weight into eight feeding
groups. Four groups were barrows and four groups were gilts. There were two
replicates based on initial weights of 64 and 54 pounds respectively. The pigs
were placed in concrete floored pens equipped with automatic watering devices
and self feeders.
The diets fed were as follows:
1. Positive control Protein sequence 17-15%.
2. Negative control Protein sequence 13-11%.
3. Diet 2 plus 0.15% lysine monohydrochloride.
4. Diet 2 plus 0.27% lysine monohydrochloride.
The composition of the diets is shown in table 1. Feeding was ad libitum.
The change to finisher rations was made at 125 lb. average weight.
Weight gain and feed consumption were measured at two week intervals.
Pigs were removed for slaughter at a weight of 210 + 5 pounds liveweight
and carcass data obtained. Carcass measurements and cut out methods have been
described previously (10).
Results and Discussion
The effects of lysine on the performance and carcass characteristics of
barrows and gilts are shown in table 2.
With both sexes combined, addition of lysine to the low protein diet resulted
in a significant improvement (P < .05) in daily gain. The higher level of added
lysine produced no additional response over that of the lower level. These im-
proved daily gains did not equal the gains produced on the higher protein diet.
Table 1. Percentage Composition of Diets 1/
Ingredient 1 2 3 4
Ground yellow corn 75.39 85.40 85.25 85.13
Soybean meal, dehulled 20.76 10.75 10.75 10.75
Biofos 3/ 2.60 2.60 2.60 2.60
Limestone 0.50 0.50 0.50 0.50
Iodized salt 0.50 0.50 0.50 0.50
Trace mineral premix 4/ 0.15 0.15 0.15 0.15
Vitamin premix 5/ 0.10 0.10 0.10 0.10
L-lysine monohydrochloride 6/ 0.15 0.27
Calculated lysine content, % 0.76 0.49 0.64 0.76
1/ At a liveweight of 125 pounds, the protein level of all diets was
lowered 2% by adjusting the amounts of corn and soybean meal.
2/ Diet 1 positive control, 17% protein;
diet 2 negative control, 13% protein;
diet 3 diet 2 plus 0.15% L-lysine monohydrochloride;
diet 4 diet 2 plus 0.27% L-lysine monohydrochloride.
3/ 21% phosphorus, 18% calcium.
4/ Premix contained: 20% zinc, 10% iron, 5.5% manganese, 1.1% copper,
0.15% iodine, 0.1% cobalt and 2% calcium.
5/ Premix contained: 6,000 mg riboflavin; 20,000 mg niacin; 12,000 mg
pantothenic acid; 80,000 mg choline chloride; 10,000 mcg Vitamin
B12; 2,500,000 IU Vitamin A; 400,000 ICU Vitamin D3 and 10,000 IU
Vitamin E per pound of premix.
6/ L-lysine monohydrochloride. Courtesy of Merck Chemical Division,
Rahway, New Jersey.
Tgble 2. Effects of Lysine Supplementation On Performance And Carcass
Characteristics Of Growing-Finishing Swine
Dietary Treatment 1/
Number of pigs
Initial wt., lb.
Final wt., lb.
Daily gain, lb. 2/
Daily feed, lb.
4 lean cuts, % 2/
Carcass length, in.
Loin eye area, so. in. 2/
Marbling score .2
Color score A/
Firmness score 5/
1/ Dietary treatments: 1. 17-15% protein
2. 13-11% protein
2/ a,b,c Values in the same
P < .05 (Duncan, 1955).
2 plus 0.15% L-lysine
2 plus 0.27% L-lysine
line with a common or
Barrows and Gilts Combined
no superscript letter are not significantly different -
3/ Scores were coded from 0 to 33; small = 10-12, modest = 13-15, moderate = 16-18, etc.
4/ Very dark color designated by 1; slightly dark, 2; greyish-pink, ideal, 3; slightly light, 4; very
5/ Very firm designated by 1; firm, 2; slightly soft, 3; very soft, 4.
Daily gain of barrows given additional lysine was not significantly different
(P < .05) from that of barrows fed the higher protein diet.
The lack of response to supplemental lysine by gilts was unexpected in view
of the gilt's apparent higher protein requirement (5, 6, 7, 8). It is possible
that other amino acid deficiencies or imbalances may have prevented the gilt from
responding to the lysine.
There was a significant gain interaction between diets and replication
(initial wt.) and an interaction approaching significance between diets and sex.
These interactions are shown in graphs 1 and 2. The gain of the lighter pigs
was significantly less than that of the heavier pigs on the low protein diet
(diet 2). The lighter pigs fed diet 2 consumed 15.4% less feed per day than the
heavier pigs fed the same diet. This difference was considerably greater than
that between heavy and light pigs fed other diets. The low consumption of the
low protein diet is believed to be the cause of the poor performance of this
group. As previously mentioned, barrows responded in gain to the added lysine
while gilts did not.
Added lysine resulted in improved feed efficiency in both gilts and barrows.
In neither case however, was feed efficiency improved to the level of the higher
Differences in dressing percentage between treatments were not significant
(P < .05). The addition of lysine improved carcass leanness as indicated by
greater percent four lean cuts, less backfat thickness, greater loin eye area
and lower marbling score. The differences were significant (P < .05) however,
only for percent four lean cuts and loin eye area. For each of these four indices,
the improved values were similar to those of the higher protein diet. While there
were no significant diet x sex interactions for these indices, in the case of loin
eye area, barrows appear to have responded more than gilts to the lysine addition.
Graph 1. Effect of Initial Weightia On
Average Daily Gain
1 2 3 4
Graph 2. Effect Of Sex On Average
a/ Heavy initial weight 64 lb., Light initial
weight 54 lb.
b/ 1,2,3,4 dietary treatments are as indicated
in table 2.
Ninety-six pigs were used to evaluate the effects of different dietary
lysine levels on performance and carcass characteristics of barrows and gilts.
Dietary treatments were: (1) 17-15% protein; (2) 13-11% protein; (3) treatment
(2) plus 0.15% lysine; (4) treatment (2) plus 0.27% lysine. All rations were
corn soybean meal and the change to the lower protein level was made at 125
Addition of lysine to the low protein ration resulted in improved gains and
feed conversion but in general the improved values did not equal those of the
higher protein diet. Growth rate of barrows was improved significantly (P < .05)
due to added lysine while that of gilts was not. The growth rate of the lighter
pigs (initial weight 54 lb.) was more adversely affected by the low protein
unsupplemented diet than was that of the heavier pigs (initial weight 64 lb.).
Carcass leanness, as measured by backfat thickness, loin eye area, % 4 lean
cuts and marbling score was improved by the lysine additions and these improve-
ments were equal to the values of the higher protein diet. While both barrows
and gilts responded to the lysine, in the case of loin eye area the barrows
appeared to have responded more than the gilts.
1. 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.
2. 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 supplementation
during the finishing period on feedlot performance, carcass characteristics
and pork acceptability. Fla. Animal Sci. Mimeo. Series AN67-10.
3. 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.
4. Wallace, H. D. 1968. Nutritional and Management Effects on Muscle Charac-
teristics and Quality. Chapter 8. The Pork Industry: Problems and Progress.
Iowa State Univ. Press, Ames, Iowa.
5. Wallace, H. D., E. W. Lucas, A. Z. Palmer and G. E. Combs. 1970. The
influence of sex on the protein requirement of growing-finishing swine.
Fla. Animal Sci. Mimeo. Series No. AN71-1.
6. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1971. The
influence of sex on the protein requirement of growing-finishing swine. Fla.
Animal Sci. Mimeo. Series No. AN71-7.
7. Wallace, H. D., E. M. Hervas, A. Z. Palmer and G. E. Combs. 1972. Influence
of protein level, slaughter weight and sex on feedlot performance and carcass
measurements of swine. Fla. Animal Sci. Mimeo. Report No. AL-1972-3.
8. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1973. Influ-
ence of sex, dietary protein level and potassium supplementation on feedlot
performance and carcass characteristics of pigs. Fla. Animal Sci. Mimeo
Report No. AL-1973-7.
9. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1972. Influ-
ence of sex, pen space and feeder holes per pig on protein consumption,
feedlot performance and carcasses of pigs fed shelled corn and supplement
free-choice. Fla. Animal Sci. Mimeo Report No. AL-1972-4.
10. Wallace, H. D., A. Z. Palmer, J. W. Carpenter and G. E. Combs. 1966. Feed
restriction of swine during the finishing period. Fla. Bul. 706.