Determination of endogenous amino acid flow at the terminal ileum of the rat

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.

Endogenous flow of total lysine and other amino acids at the distal ileurn of the protein‐or peptide‐fed rat: The chemical labelling of gelatin protein by transformation of lysine to homoarginine

“…The value for lysine flow at the terminal ileum of rats given a protein-free diet in the present study was considerably lower than a comparable value (400 pg g-' dietary dry matter) reported by Bolton and Miller (1985). Conversely, however, the present values for ileal lysine and amino acid flows for the protein-free-fed rats were higher than comparable values found by Skilton et a1 (1988) andDarragh et a1 (1990). This was also the case for flows determined after feeding the rats an EHC-based diet.…”

Composition of endogenous ileal digesta nitrogen from the rat—the use of distilled water for digesta collection

“…The ultrafiltrate N comprised mostly peptides and free amino acids, with minor contributions from urea, ammonium and creatinine. The endogenous ileal amino acid and nitrogen flows for the growing rat determined in the present study were lower than those reported by Taverner (1979) and Bolton and Miller (1985), but similar to those found by Skilton et al (1988), Darragh et a1 (1990), Moughan and Rutherfurd (1990) and Butts et ul(1991).…”

Effect of the duration of feeding of a protein-free diet on endogenous ileal nitrogen and amino acid loss in the growing pig

“…13,15,18 The high level of proline is thought to be due to the breakdown of muscle protein to supply the amino acids required for metabolism. 19 There is also evidence that the ef®cient absorption of proline is dependent on an adequate supply of protein in the diet.…”