Limiting Amino Acids in Low-Protein Corn-Soybean Meal Diets for Growing-Finishing Swine

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Abstract
Experiments were conducted with growing and finishing swine to evaluate the effectiveness of various amino acid additions to low-protein corn-soybean meal diets. Two feeding experiments were conducted with growing swine each including a 16% protein positive control diet. In the first, a 14% protein diet served as the negative control while in the second trial it was a 12% protein diet. Amino acids were supplemented to the negative control diets in each experiment. Rate and efficiency of gains from feeding either 12 or 14% protein diets were inferior to those of pigs fed the 16% protein diet. Lysine additions to the 14% protein diet resulted in pig performance similar to those fed the positive control diet. The addition of both lysine and tryptophan to a 12% protein diet for growing swine equaled the performance of pigs fed the 16% protein diet. The first- and second-limiting amino acids for growing swine from the 12% diet was suggested as being lysine and tryptophan, respectively. A nitrogen balance trial supported the observations of these latter findings. The addition of methionine or threonine to amino acid supplemented diets resulted in reduced performance. Two group-feeding experiments with finishing swine initially weighing approximately 52 kg were conducted with a positive 13%- and a negative control 10%-protein diet. Lysine, lysine + trypotphan or lysine + methionine supplementations to the negative control diet were evaluated. In the first experiment both lysine and tryptophan additions to the 10% protein diet resulted in equal performance as that of those fed the 13% protein diet, while in the second experiment lysine supplementation alone resulted in equivalent performance. Analyses of the diets of the first experiment demonstrated that the diet was lower in protein and tryptophan than calculated, while in the second experiment analytical values for protein and tryptophan were similar to calculated values. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.