Influence of a Dietary Supplement of Lysine Fed at Two Levels of Protein on Growth, Feed Efficiency and Carcass Characteristics of Swine

Abstract

Twelve and 16% protein milo-soybean meal diets were used to determine the effect of protein level and supplemental lysine on rate of gain, feed efficiency and certain carcass characteristics of growing-finishing swine. Average daily gain and feed efficiency of the pigs were higher when fed 16% protein than on 12% protein but were not significantly affected by the addition of 0.1% L-lysine to the diets. Protein and fat content were significantly higher and lower, respectively, in the LD muscle from pigs fed 16% protein compared to those fed 12% protein. Dietary protein level did not produce a significant difference in dressing percent, percent ham and loin, carcass backfat thickness, LD area and LD firmness. Pigs fed diets containing supplemental lysine had a significantly (P<.05) lower dressing percent and (P<.05) higher percent ham and loin. These two measurements indicated an increase in yield of total lean due to lysine supplementation. The addition of lysine increased the area, percent protein and firmness of the LD muscle in carcasses of pigs fed the 12% protein diets, but decreased these measurements in carcasses of pigs fed 16% protein. However, the differences were small and were not statistically significant. A significant positive correlation was obtained between the percent ham and loin of the carcasses with the area of the LD. Significant negative correlations were obtained between percent ham and loin and dry matter and fat content of the LD. Area of the LD was negatively correlated with the percent dry matter of the muscle. Also, the firmness of the LD had significant negative correlations with percent dry matter and fat of the muscle indicating that area, and firmness of the LD increased when a greater percentage of moisture and smaller percent intramuscular fat were present. The data from this experiment indicate that the lysine level fed pigs for optimum daily gain may be different from that needed for optimum lean carcass development.