Journal of Animal Science, Vol 75, Issue 1 148-158, Copyright © 1997 by American Society of Animal Science

JOURNAL ARTICLE

Evaluation of the 15N-isotope dilution technique for determining the recovery of endogenous protein in ileal digestion of pigs: effect of dilution in the precursor pool for endogenous nitrogen secretion

K. A. Lien, W. C. Sauer, R. Mosenthin, W. B. Souffrant and M. E. Dugan
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.

Three barrows, average initial BW of 35 kg, were fitted with a re-entrant cannula at the distal ileum and catheters in each of the external jugular veins. The barrows were fed twice daily a diet containing barley as the sole source of protein. A 1-d intravenous infusion of saline was followed by an 8-d continuous infusion of [15N]leucine at a rate of 30 mg/(kg BW x d). Blood samples, taken hourly for 9 d, were pooled over the 12-h period between feeding. Ileal digesta were collected hourly on d 3 and 8 of the [15N]leucine infusion and pooled over 12 and 24 h. Enrichments (atom percentage excess 15N) in nitrogen (N), leucine, isoleucine, valine and alanine were measured in the trichloroacetic acid (TCA)-soluble and -insoluble fractions of plasma and in ileal digesta. Although the enrichments in N were similar in all pools, enrichments in amino acids in the TCA-soluble fraction of plasma were at least twice that in the TCA-insoluble fraction and in ileal digesta. The estimated contributions of endogenous N and amino acids to total N and amino acids in ileal digesta were 82.3 +/- 9.38, 39.0 +/- 3.83, 43.8 +/- 6.50, 51.9 +/- 3.24, and 51.9 +/- 9.80 for N, leucine, isoleucine, valine and alanine, respectively. The results from this study indicate that enrichments in total N in the TCA-soluble fraction of plasma may not accurately reflect enrichments in endogenous N secreted into the intestinal lumen. This factor should be considered when using the 15N-isotope dilution technique to estimate the recovery of endogenous protein in ileal digesta of pigs fed protein-containing diets.

This article has been cited by other articles:

				H. Lapierre, D. R. Ouellet, R. Berthiaume, R. Martineau, G. Holtrop, and G. E. Lobley Distribution of 15N in Amino Acids During 15N-Leucine Infusion: Impact on the Estimation of Endogenous Flows in Dairy Cows J Dairy Sci, July 1, 2008; 91(7): 2702 - 2714. [Abstract] [Full Text] [PDF]

				C. A. (C. Steendam, M. W. A. Verstegen, S. Tamminga, H. Boer, M. van 't End, B. Verstappen, W. R. Caine, and G. H. Visser Route of Tracer Administration Does Not Affect Ileal Endogenous Nitrogen Recovery Measured with the 15N-Isotope Dilution Technique in Pigs Fed Rapidly Digestible Diets J. Nutr., November 1, 2004; 134(11): 3068 - 3075. [Abstract] [Full Text] [PDF]

				C. A. (C. Steendam, S. Tamminga, H. Boer, E.-J. de Jong, G. H. Visser, and M. W. A. Verstegen Ileal Endogenous Nitrogen Recovery Is Increased and Its Amino Acid Pattern Is Altered in Pigs Fed Quebracho Extract J. Nutr., November 1, 2004; 134(11): 3076 - 3082. [Abstract] [Full Text] [PDF]

				S. M. Hodgkinson, W. B. Souffrant, and P. J. Moughan Comparison of the enzyme-hydrolyzed casein, guanidination, and isotope dilution methods for determining ileal endogenous protein flow in the growing rat and pig J Anim Sci, October 1, 2003; 81(10): 2525 - 2534. [Abstract] [Full Text] [PDF]

				P. Leterme, B. Sève, and A. Théwis The Current 15N-Leucine Infusion Technique Is Not Suitable for Quantitative Measurements of Ileal Endogenous Amino Acid Flows in Pigs J. Nutr., November 1, 1998; 128(11): 1961 - 1968. [Abstract] [Full Text]

				V. Hess, J. N. Thibault, and B. Sève The 15N Amino Acid Dilution Method Allows the Determination of the Real Digestibility and of the Ileal Endogenous Losses of the Respective Amino Acid in Pigs J. Nutr., November 1, 1998; 128(11): 1969 - 1977. [Abstract] [Full Text]

				B. Stoll, J. Henry, P. J. Reeds, H. Yu, F. Jahoor, and D. G. Burrin Catabolism Dominates the First-Pass Intestinal Metabolism of Dietary Essential Amino Acids in Milk Protein-Fed Piglets J. Nutr., March 1, 1998; 128(3): 606 - 614. [Abstract] [Full Text]