Mesure de la digestibilité des protéines par la méthode des différences porto-artérielles chez l’espèce porcine

Assessing the digestibility of proteins using the porto-arterial difference method in pigs

Laboratoire de Sciences Animales ENSAIA-INRA, 2 av. de la Forêt de Haye 54505 Vandœuvre cedex

Abstract

This paper gives an overview of the current in vivo methods used to evaluate nutritional quality of proteins. It present in the first part methods used to assess digestibility of proteins, the interest and constraints of portal measurements and finally questions regarding digestive interactions between alimentary nitrogen and endogenous nitrogen are discussed. The second part of this paper is focused on the presentation of a study which was aimed to determine 15N porto-arterial kinetics after ingestion of 15N labelled milk, yogurt or heat treated yogurt. It indicates an original method which combines 15N isotope protein labelling and postprandial porto-arterial measurements in growing pigs. 15N portal absorption in the growing pig were performed after ingestion of uniformly (0.2509 APE) labelled 15N milk (M), yogurt (Y) and heat treated yogurt (HY). The highest porto-arterial differences of 15N were found in the period between 30 min and 90 min after ingestion. Main absorption of nitrogen from M and HY occurs during the 0-120 min time period (about 74% for M and 68% for HY). For Y, a larger displayed absorption period over the 0-240 min time period was observed. 15N absorption rate is close to 75% for each studied milk product, suggesting that M, Y and HY deliver nearly the same amounts of nitrogen to the organism. These results also indicate that major part of proteins are absorbed within the 240 min postprandial period.