Endogenous flow of amino acids in the avian ileum as influenced by increasing dietary peptide concentrations

• Published in: British journal of nutrition Vol. 101; no. 6; pp. 822 - 828
• Main Authors: Ravindran, Velmurugu, Model, Patrick C.H, Rutherfurd, Shane M, Thomas, Donald V
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 28-03-2009
• Subjects: Amino acids; Amino Acids - analysis; Amino Acids - metabolism; Animal Feed; Animals; Biological and medical sciences; broiler chickens; broiler feeding; Caseins - administration & dosage; Chickens; Chickens - metabolism; Diet; Dietary Proteins - administration & dosage; Dietary Proteins - metabolism; dose response; endogenous sources; Enzyme-hydrolysed casein; Enzymes; experimental diets; Feeding. Feeding behavior; Flow; Fundamental and applied biological sciences. Psychology; Gastrointestinal Contents - chemistry; Hydrolysis; Ileal endogenous amino acid flow; ileum; Ileum - metabolism; Male; Molecular weight; nutrient intake; Peptides; protein composition; protein metabolism; Proteins; Small intestine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; New Zealand; Peptides; Digestive system; Enzyme; Concentration; Small intestine; Ileum; Vertebrata; Endogenous; Mammalia; Casein; Aminoacid; Ileal endogenous amino acid flow: Enzyme-hydrolysed casein: Chickens; Chicken; Aves
• ISSN: 0007-1145; 1475-2662
• DOI: 10.1017/s0007114508039974

The aim of the present study was to establish whether feeding broiler chickens with diets containing increasing dietary peptide concentrations would cause increases in ileal endogenous amino acid flow. The flow of N and most amino acids increased quadratically (P < 0·05 to 0·001) with increasing dietary concentrations of peptides. The exceptions were the flow of threonine, serine, glycine, tyrosine and cystine, which increased linearly (P < 0·001) with dietary peptide levels. Another notable exception to the general trend was the flow of proline, which was significantly higher (P < 0·01) in birds fed the protein-free diet. The amino acid profile of endogenous protein, expressed as proportion of crude protein, indicated that the ratios of threonine, glutamic acid, proline, glycine, leucine, histidine, arginine and cystine were influenced (P < 0·05) with increasing dietary peptide concentrations. In general, compared with the protein-free diet, the ratios of threonine and arginine in endogenous protein were lower (P < 0·05) and those of glutamic acid, glycine and histidine were greater (P < 0·05) in diets with high concentrations of peptides. The ratio of proline was found to decrease (P < 0·05) with increasing dietary peptide concentrations. These changes in the amino acid profile of endogenous protein are probably reflective of changes in the output of one or more of the components of endogenous protein. Overall, the present results demonstrated that increasing dietary peptide concentrations increased the flow of endogenous amino acid flow at the terminal ileum of broiler chickens in a dose-dependent manner and also caused changes in the composition of endogenous protein. The observed changes in endogenous amino flow will influence the maintenance requirements for amino acids and also have implications for the calculation of true digestibility coefficient of feedstuffs.