title: Gut endogenous nitrogen and amino acid excretions in adult domestic cats fed a protein-free diet or an enzymatically hydrolyzed casein-based diet.
abstract: Ileal and fecal gut endogenous nitrogen and amino acid excretions in adult domestic cats were determined. Ileal digesta were collected (10 cm of terminal ileum) from the cats fed either a protein-free diet or an enzymatically hydrolyzed casein-based diet (free amino acids and peptides < 10,000 Da) for 1 wk. Chromic oxide was included in each diet as an indigestible marker. The relative contribution of the hindgut to total endogenous gut excretion was investigated in a separate study by feeding cats a protein-free diet with or without added antibiotics for 10 d. Endogenous ileal nitrogen and amino acid nitrogen excretions of (mean +/- SEM 2.4 +/- 0.27 and 1.9 +/- 0.13 mg/g food dry matter intake, respectively, were found for the cats fed the protein-free diet, whereas higher excretions of 3.6 +/- 0.73 (P = 0.12) and 3.6 +/- 0.76 (P = 0.03) mg/g food dry matter intake were obtained in cats fed the enzymatically hydrolyzed casein. Significantly (P < 0.05) higher endogenous ileal amino acid excretions, for the enzymatically hydrolyzed casein-fed cats compared with those fed the protein-free diet, were found for methionine, aspartic acid, serine, glutamic acid, proline, valine and isoleucine, with the differences in excretions of glycine, alanine, leucine and histidine being significant at the 6% level. Most of the endogenous fecal amino acid excretions were unaffected by the inclusion of the antibiotics in the protein-free diet, although bacterial numbers were significantly lower (69%). Antibiotics addition led to significantly higher fecal endogenous excretions of nitrogen, taurine, threonine, serine and histidine but significantly lower excretions of methionine and lysine. Cats, like other simple-stomached mammals, excrete higher amounts of endogenous amino acids at the terminal ileum when the diet contains peptides.
authors.affiliation: Monogastric Research Centre, Department of Animal Science, Massey University, Palmerston North, New Zealand.
authors.forename: W H
authors.initials: WH
authors.lastname: Hendriks
authors.forename: P J
authors.initials: PJ
authors.lastname: Moughan
authors.forename: M F
authors.initials: MF
authors.lastname: Tarttelin
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology; D002364:Caseins / Q000008:administration & dosage*; D002415:Cats; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage*; D005243:Feces / Q000737:chemistry; D006868:Hydrolysis; D007082:Ileum / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D002364:Caseins; D004044:Dietary Proteins; D009584:Nitrogen