The Methionine-Cystine Need of the Young Pig

Abstract

Weanling pigs weighing approximately 28 lb. were used to measure the methionine-cystine requirement and the effect of dietary antibiotics thereon. A synthetic diet containing 12.6 percent isolated soybean protein and 0.15 percent methionine plus 0.17 percent cystine was deficient in methionine to support normal performance of the weanling pig. Additions of 0.1 or 0.2 percent of L-cystine to the deficient diet failed to improve performance. A level of 0.25 percent methionine in the presence of 0.17 percent cystine supported satisfactory rate and efficiency of gain. Expressed as a percentage of the dietary protein the combined methionine-cystine requirement is approximately 3.33 percent of the protein. Cystine can apparently provide about 40 percent of the need for sulfur-bearing amino acids. Supplementary levels of 0.3 or 0.4 percent DL-methionine produced an inhibition of growth. The weanling pig can utilize DL-alpha-hydroxy-gamma-methylmer-capto butyric acid to at least partially satisfy the methionine requirement for normal growth. Dietary antibiotics produced a marked improvement in the rate and efficiency of gains. However, antibiotics did not influence the response of the pig to levels of DL-methionine or to methionine hydroxy analogue. Copyright © . .