Recovery and composition of endogenous protein collected at the terminal ileum as influenced by the age of broiler chickens

Abstract

The recovery and composition of endogenous protein at the terminal ileum of broiler chickens were determined at 14 and 42 days post-hatching using the peptide alimentation method. The ileal endogenous flows of nitrogen and amino acids, expressed as mg/kg dry matter intake, differed (P < 0.05–0.01) between the two age groups, with flows increasing with age, except for lysine, histidine and glycine. The flows of lysine and histidine were unaffected (P > 0.05) by age, whereas a tendency (P = 0.07) for increased loss with age was observed for glycine. The amino acid profile of ileal endogenous protein, expressed as g/100 g crude protein, did not differ (P > 0.05) between 14-day- and 42-day-old broilers, suggesting that the relative proportions of the individual sources that contribute to the endogenous protein were similar at both ages. In both age groups, the most abundant amino acids in the ileal endogenous protein were glutamic acid, aspartic acid, proline, serine, glycine, and threonine. The present findings suggest that, when determining true digestibility, corrections using endogenous amino acid flows determined with broilers of a particular age to apparent amino acid digestibility values determined with birds of a different age would clearly result in less accurate true digestibility estimates.