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The 15 N‐isotope dilution method for determining ileal endogenous nitrogen excretion in the young (10 kg liveweight) pig
Author(s) -
Schulze Hagen,
Butts Christine A,
Moughan Paul J,
Verstegen Martin W A
Publication year - 1995
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740690108
Subject(s) - ileum , leucine , isotope dilution , chemistry , amino acid , endogeny , nitrogen balance , excretion , zoology , small intestine , biochemistry , nitrogen , chromatography , medicine , biology , mass spectrometry , organic chemistry
A study was conducted with four crossbred 5‐week‐old castrated male pigs at an average body weight of 10 kg to determine the endogenous amino acid and nitrogen flows at the terminal ileum using the peptide alimentation and 15 N‐isotope dilution methods. The pigs were fitted with a post‐valvular T caecal cannula and two indwelling blood catheters. They were fed a cornstarch‐based semisyn'hetic diet formulated to contain enzymically hydrolysed casein (EHC) as the sole source of nitrogen at twice their maintenance requirement for energy. Digesta were centrifuged and ultrafiltrated after collection and the precipitate plus retentate fraction (mol wt > 10000) was used to determine the endogenous amino acid and nitrogen flows. To estimate the endogenous N flow at the terminal ileum of these EHC‐fed pigs using the 15 N‐isotope dilution method a constant 10 day 15 N‐leucine infusion was performed at a daily rate of 5‐04 mg of 15 N‐leucine (95% 15 N enrichment) kg −1 body weight. The mean 15 N‐enrichments above background for the trichloroacetic acid soluble blood plasma and ileal digesta nitrogen pools were 0.0249 and 0.0178, respectively. There were no statistically significant differences for 15 N‐enrichment excess between the days of ileal digesta collection. The results demonstrated that glutamic acid, aspartic acid, proline and serine formed about 50% of the total ileal endogenous amino acid flow. The total daily amount of endogenous amino acid flow at the terminal ileum was 6.2 g day −1 . The endogenous ileal N flows determined with the peptide alimentation and the 15 N‐isotope dilution methods were similar (P = 0.40) at 1.37 and 1.17 g day −1 , respectively. Endogenous N as a proportion of total N flow passing the terminal ileum was 83% and 72% for the peptide alimentation and the 15 N‐isotope dilution method, respectively. The study provides some support for application of the 15 N‐isotope dilution method with pigs.