Sulfur Amino Acid Activity of Glutathione,DL-α-Hydroxy-Methionine,and α-Keto-Methionine in Chicks

Summary

Male crossbred chicks were fed crystalline amino acid diets to evaluate the sulfur amino acid activity of glutathione, DL-α-OH-methionine (dl-α-OH-M), and α-keto-methionine (α-keto-M). Relative to L-cystine at isosulfurous levels, glutathione had a cystine-sparing value of 100%. Chicks fed α-keto-M gained 83% as fast as those fed an equal sulfur contribution from l-methionine, and those fed DL-α-OH-M gained 53% as fast. Addition of 1% gluta-mine to the purified diet failed to enhance the efficacy of dl-α-OH-M, indicating that glutamine is not a limiting dietary factor in the conversion of DL-α-OH-M to L-methio-nine.