EFFECTS OF DIETARY GLYCINE PLUS SERINE ON STARTING BROILER CHICK PERFORMANCE AS INFLUENCED BY DIETARY CRUDE PROTEIN-LEVELS

Two growth studies in starting broilers were performed to determine th e effects of dietary glycine+serine levels on growth and FCE from 5 to 20 or 22 days of age. Crystalline glycine was added to basal diets co ntaining 1.03% Gly+Ser and 17.3% CP in expt. 1, and 1.43% Gly+Ser and 20% CP or 1.50% and 23% CP in expt. 2. Significant growth and FCE resp onses to added glycine were obtained in both experiments. The response s were not an effect of nonessential amino acid supply, because glutam ic acid, which was alternatively added in expt. 1, did not yield a res ponse similar to the response to glycine. An increase in dietary prote in appears to result in an elevated requirement for Gly+Ser. Estimated dietary optimum contents for Gly+Ser range from 1.5% to 1.6% at 17% C P up to 1.7% to 1.8% at 23% CP.