Amino acid requirements of growing chickens

Abstract

1. Using 18% protein diets (N × 6.25), consisting mainly of conventional ingredients of known amino acid composition, the amino acid requirements as percentages of diet and of dietary protein respectively for broiler chickens between 14 and 28 d of age were found to be: threonine 0.50–0.52% of diet (2.8–2.9% of dietary protein); glycine 0.48–0.50 (2.7–2.8); valine 0.69–0.71 (3.8–3.9); methionine + cystine 0.58 (3.2); iso‐leucine <0.48 (<2.7); leucine <1.05 (<5.8); tyrosine + phenylalanine 1.09–1.12 (6.1–6.2); lysine 0.87 (4.8); histidine <0.34 (<1.9); arginine <0.76 (<4.2); tryptophan < 0.14 (< 0.78). 2. Values found were in general lower than those determined using diets consisting entirely of purified amino acids and the reasons for this are discussed.