title: Composition of nitrogen-containing fractions in digesta from the distal ileum of pigs fed a protein-free diet.
abstract: The levels of free, peptide-bound and protein-bound amino acid nitrogen in endogenous N at the distal ileum of the pig were determined when the digestion of protein after sample collection was minimized. Six 14-kg pigs were fed a protein-free diet and samples of digesta from the distal ileum were collected. The digesta were centrifuged and the supernatant ultrafiltered. On average, 86% of the total N in the digesta was found in the precipitate + retentate (greater than 10,000 mol. wt.) fraction, and in this fraction 78% of the total N was protein N. Of the total N in the ultrafiltrate (less than 10,000 mol. wt) the majority (69%) was peptide N. Amino N (free amino acid plus peptide) in the ultrafiltrate was 11% of the total N in the whole ileal digesta. Non-amino N (urea N + ammonium N + creatinine N) was only 0.73% of the total N in the whole ileal digesta. The mean amounts of nitrogen from individual amino acids (free + peptide) in the ultrafiltrate (expressed as percentages of the total nitrogen for the respective amino acid in whole ileal digesta) were low, ranging from 3.0% for isoleucine to 16.6% for proline. The finding that free amino acid N + peptide N is a small fraction of total N in endogenous ileal digesta supports the use of a new method for determining endogenous loss, whereby the animal is fed hydrolyzed casein and the ileal digesta are ultrafiltered. The high-molecular-weight fraction provides a measure of endogenous nitrogen loss.
authors.affiliation: Department of Animal Science, Massey University, Palmerston North, New Zealand.
authors.forename: P J
authors.initials: PJ
authors.lastname: Moughan
authors.forename: G
authors.initials: G
authors.lastname: Schuttert
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage*; D004063:Digestion; D007082:Ileum / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism*; D011488:Protein Deficiency / Q000378:metabolism; D013552:Swine
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D009584:Nitrogen