| Abstract: | 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 15N-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 15N-isotope dilution method a constant 10 day 15N-leucine infusion was performed at a daily rate of 5-04 mg of 15N-leucine (95% 15N enrichment) kg?1 body weight. The mean 15N-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 15N-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 15N-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 15N-isotope dilution method, respectively. The study provides some support for application of the 15N-isotope dilution method with pigs. |
