Evidence of a Specific Effect of Cystine in the Prevention of Nutritional Muscular Dystrophy in Vitamin E-Deficient Chicks

Abstract

A number of experiments were conducted using a vitamin E-deficient, purified diet containing approximately one-half of the chick's requirement of methionine and approximately one-fifth of the required level of cystine. Muscular dystrophy occurred in 90 to 100% of the chicks within 5 weeks. Addition of 0.15% of L-cystine completely prevented muscular dystrophy without increasing growth. In contrast, the addition of 0.19% of DL-methionine or 0.15% of L-methionine improved growth but produced no appreciable decrease in the incidence or severity of muscular dystrophy. When the growth of the chicks receiving added methionine was approximately equilibrated to that of the chicks receiving cystine, by feeding both lots equal amounts of feed, the addition of L-cystine at 0.15% prevented muscular dystrophy, whereas equi-sulfur supplementation in the form of methionine did not. Evidence was obtained indicating that the effect of arginine upon nutritional muscular dystrophy in chicks is that its addition to the diet decreases the effectiveness of methionine for the prevention of muscular dystrophy; arginine supplementation appeared to have no inhibitory action upon the effect of cystine. The results indicate, therefore