[en] The current 15N-leucine infusion technique may overestimate the ileal endogenous nitrogen losses in pigs. To determine the reason, we infused four cannulated pigs intravenously, fed them a pea-based diet with 15N-leucine, and examined some methodological variables. Neither the blood sampling time nor the choice of precursor pool (total N or amino acid N of deproteinized plasma) or the method of estimation of the isotopic equilibrium level significantly affected the results. On the other hand, the 15N-enrichment of purified mucin, isolated from ileal digesta, was higher than that of the plasma amino acid pool (0.114 vs. 0.077 atom % excess). The endogenous proportion of the labeled amino acids (Ala, Gly, Ile, Leu and Val) in the ileal digesta ranged from 23 (Leu) to 74% (Ala), compared with 70% for total N. The low value of leucine was ascribed to the constant marker infusion condition. In pigs infused with 13C-leucine, a similar endogenous proportion was obtained for lumenal leucine with 13C-leucine and 15N-leucine infusion. However, the 13C-enrichment of the leucine bound to mucin was markedly lower than that of plasma leucine (38%). The endogenous amino acid flows were also estimated by combining the ileal N flow measured with 15N and the endogenous amino acid profile obtained by means of an N-free diet. They were different from those obtained with the 15N-amino acid dilution technique. We conclude that the precursor pool currently used (plasma total N or total a-amino acid N pools) is a poor indicator of the enrichment of the secretions and that the infusion of one labeled amino acid is not sufficient to extend the method at the amino acid level.
Disciplines :
Animal production & animal husbandry Agriculture & agronomy
Author, co-author :
Leterme, Pascal; Faculté Universitaire des Sciences Agronomiques de Gembloux - FUSAGx > Unité de Zootechnie
Seve, Bernard; Inra > Station de Recherches Porcines
Thewis, André ; Université de Liège - ULiège > Gembloux Agro-Bio Tech
Language :
English
Title :
The Current N-15-Leucine Infusion Technique Is Not Suitable For Quantitative Measurements Of Ileal Endogenous Amino Acid Flows In Pigs
Publication date :
1998
Journal title :
Journal of Nutrition
ISSN :
0022-3166
eISSN :
1541-6100
Publisher :
American Society of Nutritional Sciences, Bethesda, United States - Maryland
Alpers, D. (1972) Protein synthesis in intestinal mucosa: the effect of route of administration of precursor amino acids. J. Clin. Investig. 51: 167-173.
Corring, T., Jung, J. (1972) The amino acid composition of pig pancreatic juice. Nutr. Rep. Int. 6: 187-190.
de Lange, C., Souffrant, W. & Sauer, W. (1990) Real ileal protein and amino acid digestibilities in feedstuffs for growing pigs as determined with the 15N-isotope dilution technique. J. Anim. Sci 68: 409-418.
François, E., Thill, N. & Théwis, A. (1978) Méthode rapide de dosage de l'oxyde de chrome dans les aliments, les fèces et les contenus digestifs par titrage après oxydation nitro-perchlorique. Ann. Zootec. 27: 355-361.
Gabert, V., Canibe, N., Jørgensen, H., Eggum, B. & Sauer, W. (1997) Use of 15N-amino acid isotope dilution techniques to determine endogenous amino acids in ileal digesta in growing pigs. Acta Agric. Scand. Sect. A Anim. Sci. 47: 168-177.
Gaudichon, C., Laurent, C., Mähe, S., Marks, L., Tomé, D. & Krempf, M. (1994) Rate of 15N-leucine incorporation and determination of nitrogenous fractions from gastro-jejunal secretion in fasting humans. Reprod. Nutr. Dev. 34: 349-359
Grala, W., Verstegen, M., Jansman, A., Huisman, J. & van Leeuwen, P. (1998) Ileal apparent protein and amino acid digestibilites and endogenous nitrogen losses in pigs fed soybean and rapeseed products. J. Anim. Sci. 76: 557-568.
Hess, V., Thibault, J. N. & Sève, B. (1997) Apparent, true and real digestibility of intact or hydrolysed isolated pea protein. In: Proceedings of the 7th International Symposium on Digestive Physiology in Pigs (Laplace, J. P., Février, C. & Barbeau, A., eds.), pp. 587-590. EAAP Publication no.88, St-Malo, France.
Hoerr, A., Matthews, D., Bier, D. & Young, V. (1991) Leucine kinetics from [2H3]- and [13C]-leucine infused simultaneously by gut and vein. Am. J. Physiol. 260 (Endocrin. Metab. 23): E111-E117.
Husek, P. (1991) Rapid derivatization and gas chromatographic determination of amino acids. J. Chromatogr. 552: 289-299.
Leterme, P., Froidmont, E., Rossi, F. & Théwis, A. (1998) The high water-holding capacity of pea inner fibers affects the ileal flow of endogenous nitrogen and amino acids. J. Agric. Food Chem. 46: 1927-1934.
Leterme, P., Théwis, A., François, E., van Leeuwen, P., Wathelet, B. & Huisman, J. (1996a) 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. J. Nutr. 126: 2188-2198.
Leterme, P., Théwis, A., van Leeuwen, P., Monmart T. & Huisman, J. (1996b) Chemical composition of pea inner fibre isolates and their effect on the endogenous digestive secretions in pigs. J. Sci. Food Agric. 72: 127-134.
Lien, K., Sauer, W. & Dugan, M. (1997a) Evaluation of the 15N-isotope dilution technique for determining the recovery of endogenous protein in ileal digestion of pigs: effect of pattern of blood sampling, precursor pools and isotope dilution technique. J. Anim. Sci. 75: 159-169.
Lien, K., Sauer W., Mosenthin R., Souffrant W. & Dugan, M. (1997b) 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. J. Anim. Sci. 75: 148-158.
Ljunqvist, O., Persson, M., Ford, G. & Nair, K. (1997) Functional heterogeneity of leucine pools in human skeletal muscle. Am. J. Physiol.(Endocrin.& Metab. 36): E564-E570.
Mantle, M. & Allen, A. (1981) Isolation and characterization of the native glycoprotein from pig small intestinal mucus. Biochem. J. 195: 267-275.
Matthews, D., Schwarz, H., Yang, R., Motil K., Young, V. & Bier, D. (1982) Relationship of plasma leucine and α-ketoisocarpoate during a L-[1-13C] leucine infusion in man: a method for measuring human intracellular leucine tracer enrichment. Metabolism 31: 1105-1112.
Rérat, A., Jung, J. & Kandé, J. (1988) Absorption kinetics of dietary hydrolysis products in conscious pigs given diets with different amounts of fish protein. 2. Individual amino acids. Br. J. Nutr. 60: 105-120.
Sève, B. & Leterme, P. (1997) Amino acid fluxes in the pig. In: Proceedings of the 7th International Symposium on Digestive Physiology in Pigs (Laplace, J. P., Février, C. & Barbeau, A., eds.), pp. 304-315. EAAP Publication no. 88, St-Malo, France.
Simon, O., Zebrowska, T., Bergner, H. & Münchmeyer, R. (1983) Investigations on pancreatic and stomach secretion in pigs by means of continuous infusion of 14C-amino acids. Arch. Tierernähr. 33: 9-22.
Souffrant, W., Rérat, A., Laplace, J. P., Darcy-Vrillon, B., Köhler, R., Corring, T. & Gebhardt, G. (1993) Exogenous and endogenous contributions to nitrogen fluxes in the digestive tract of pigs fed a casein diet. III. Recycling of endogenous nitrogen. Reprod. Nutr. Dev. 33: 373-382.
Stall, B., Henry, J., Reeds, P., Yu, H., Jahoor, F. & Burrin, D. (1998) Catabolism dominates the first-pass intestinal metabolism of dietary essential amino acids in milk protein-fed piglets. J. Nutr. 128: 606-614.
van Leeuwen, P., van Kleef, D., van Kempen, G., Huisman, J. & Verstegen, M. (1991) The post-valve T-caecum cannulation technique: an alternative method for chyme collection in pigs. J. Anim. Physiol. Anim. Nutr. 65: 183-193.
Vanvenrooij, W., Kuijper-Lenstra, A. & Kramer, M. (1973) Interrelationship between amino acid pools and protein synthesis in the rat submandibular gland. Biochim. Biophys. Acta 312: 392-398.
Yu, Y., Wagner, D., Tredget, E., Walaszewski, J., Burke, J. & Young, V. (1990) Quantitative role of splanchnic region in leucine metabolism: L-(1-13C, 15N) leucine and substrate balance studies. Am. J. Physiol 259 (Endocr. Metab. 22): E36-E51.
