Lysine and Methionine Additions to Corn-Soybean Meal Diets for Growing Swine: Effects on Rate and Efficiency of Gain and Carcass Characteristics

Abstract

Three hundred twenty-four growing pigs were used in two experiments to determine the effects of lysine and lysine and methionine supplementation of 12 and 14% corn-soybean meal diets on rate and efficiency of gain and carcass leanness. The influence of levels of dietary protein (12, 14 and 16%) on these criteria of performance was also studied. Two hundred sixty-six pigs were slaughtered to obtain carcass data. The addition of lysine, alone or in combination with methionine, to make the 12% protein diet equivalent in these amino acids to diets containing 14 and 16% protein, or to make 14% protein diet equivalent to the 16% protein diet, did not significantly affect rate of gain, efficiency of feed utilization, backfat thickness, cross-sectional area of the longissimus dorsi muscle or yield of trimmed ham and loin. Similarly, level of dietary protein was without significant effect on rate and efficiency of gain or carcass leanness. The basal diets containing 12 and 14% protein contained 0.S6 and 0.65% lysine, respectively. The lack of a response to supplemental lysine may indicate that the amino acid was readily available and that the quantity was adequate to meet the needs of the pigs of the genotype used in this study.