Growth and Creatine Biosynthesis in the Chick as Affected by the Amino Acid Deficiencies of Casein ,

Abstract

A purified diet containing 25% casein employed in this study was supplemented with creatine, factorially with arginine, glycine and methionine, and was further compared to a practical starting ration. Two replicates, one of each sex, were used and weights and muscle creatine levels determined at 4-day intervals over a 4-week period. For growth, arginine was the most limiting amino acid. Glycine and methionine alone gave no response. Glycine in combination with arginine gave optimum growth equal to growth on the practical diet. Methionine in double or triple combination gave a slight but non-significant growth response. Creatine showed but a slight improvement in growth above the unsupplemented casein diet. For creatine formation, arginine plus glycine was required for optimum results. The muscle creatine level increased linearly with age over the 4-week period studied.