No abstract

A B S T R A C TIn a comparative study endogenous amino acid jlow was determined in twenty-four 190-g male rats (protein-replete) given diets containing synthetic amino acids as the sole nitrogen source but devoid of specific amino acids, and six rats fed a protein-free diet. Endogenous flows were not significantly different ( P > 0.05) for aspartic acid, glutamic acid, serine and lysine but were significantly higher ( P < 0.05) under protein free alimentation than amino acid alimentation for proline, glycine and alanine. This indicates that the protein-free method did not lead to lowered endogenous amino acid excretions owing to an altered amino acid metabolism in the protein-free state. The loss of some amino acids may be enhanced under protein-fiee alimentation. The high apparent digestibility of the synthetic amino acids not excluded from the diets (histidine, arginine, threonine, d i n e , isoleucine, leucine, tyrosine, phenylalanine) indicated that their iled excretions were mainly of endogenous origin. There were no significant differences (P> 0.05) between the latter excretions and those obtained by feeding the rats a protein-free diet.

A B S T R A C T The true ileal digestibility of nitrogen was determined in 20 meut und bone meul samples using I20 growing rats. Correction for endogenous ileal nitrogen excretion was based on heding a jurther