Title
The use of 15N-labeled dietary proteins for determining true ileal amino acid digestibilities is limited by their rapid recycling in the endogenous secretions of pigs
Author
Leterme, P.
Théwis, A.
François, E.
van Leeuwen, P.
Wathelet, B.
Huisman, J.
Instituut voor Landbouwkundig Onderzoek en Biochemische Produkten TNO
Publication year
1996
Abstract
We assessed the use of 15N-labeled dietary proteins as a possible tool for the determination of the true ileal amino acid (AA) digestibility in pigs. The first experiment was designed to study the dietary N excretion pattern at the ileum subsequent to the ingestion of a single 15N-labeled meal. In a second experiment, we compared ileal endogenous AA outputs and true AA digestibility estimates obtained in pigs ingesting 15N-labeled dietary proteins in a single meal vs. intravenous infusion of [15N]Ieucine for 10 d during the ingestion of a pea-based diet and a protein-free starch diet. The proportion of endogenous N found in the ileal digesta differed when the label was delivered orally (50%) vs. intravenously (72%) and changed with time. As a consequence, the true ileal AA digestibilities measured with labeled diets were lower. A third experiment demonstrated that this was due to the rapid recycling of labeled dietary N in endogenous moieties, because 15N was found in blood within 10 min of consuming the labeled meal, within 50 min of consumption in pancreatic enzymes, 90 min in bile and 4 h in ileal mucins. We conclude that the use of 15N-labeled meals for determination of true ileal AA digestibilities is limited by the fast recycling of dietary N in endogenous secretions following a single 15N-labeled meal. The accuracy of results will depend on meaningful estimates of AA flow during a limited period and accurate estimates of 15N in AA.
Subject
Biology
15N
Endogenous
Ileal digestibility
Pigs
Amino acid
Amino acid blood level
Amino acid metabolism
Animal experiment
Digestion
Nonhuman
Protein secretion
Small intestine absorption
Swine
Animal
Blood
Chemistry
Enzymology
Metabolism
Physiology
Protein intake
Time
Wheat
Amino Acids
Animals
Bile
Dietary Proteins
Digestion
Enzymes
Ileum
Leucine
Male
Mucins
Nitrogen
Nitrogen Isotopes
Pancreas
Peas
Starch
Swine
Time Factors
Triticum
To reference this document use:
http://resolver.tudelft.nl/uuid:00920243-5f31-45c7-9360-1dc4d4f62f30
TNO identifier
233433
ISSN
0022-3166
Source
Journal of Nutrition, 126 (9), 2188-2198
Document type
article