Studies on the Utilization of the α-Hydroxy Acid of Methionine by Chicks Fed Crystalline Amino Acid Diets

Abstract

Three experiments were conducted to study the influence of dietary branched-chain amino acid level and source of nitrogen in a nonessential nitrogen mixture on the utilization of the α-hydroxy acid of methionine (OH-methionine), as compared with an equimolar quantity of l-methionine, by chicks fed corn starch-crystalline l-amino acid diets. l-methionine or OH-methionine were the only sulfur-containing acids added to the diets. Chicks fed diets containing OH-methionine grew at reduced rates and required more feed per gram of body weight gain than was noted for chicks fed diets containing l-methionine when the levels of branched chain amino acids (BCAA) were not growth-limiting. The mean weight gains and feed efficiencies of chicks fed sub-optimum and greater than optimum levels of BCAA did not support the concept that BCAA serve as amino group donors for OH-methionine utilization by the chick. No dietary glutamic acid requirement was observed for the maximal utilization of OH-methionine by the chick. An additional 0.18% OH-methionine significantly (P < .05) improved chick growth and feed efficiencies to levels which were similar to those of chicks fed diets containing 0.7% l-methionine. A significant influence of the various dietary modifications included in these studies of kidney leucine aminotransferase or liver glutamate dehydrogenase was not observed.