The Amino Acid Composition and Nutritive Value of Proteins

Abstract

Male weanling rats were fed amino acid diets ad libitum in three-week growth experiments. The requirements of L-phenylalanine in the presence of excess L-tyrosine (0.7%) and of L-methionine in the presence of excess L-cystine (0.5%) were found to be 0.4 and 0.16% of the diet, respectively, which can be supplied as tyrosine or phenylalanine, and as cystine or methionine. Rats fed a complete L-amino acid diet containing all the amino acids at their minimal requirement levels in a 10% conventional protein (N × 6.25) ration grew normally.