Influence of Dietary Protein Level and Source on the Course of Protein Digestion Along the Small Intestine of the Veal Calf

摘要

The objective of this study was to examine the effect of the dietary crude protein (CP) content and source on the distribution of digesta proteins and peptides according to their molecular mass along the small intestine of veal calves. Diets contained 14, 104, 205, and 279g/kg of CP supplied by skim milk powder (SMP) in experiment 1. Diets contained only SMP or SMP plus proteins (1:1 on digestible CP basis) from either a soybean protein concentrate (SPC), an isolated soy protein partially hydrolyzed (HSPI), or a potato protein concentrate (PPC) in experiment 2. Duodenal, jejunal, and ileal digesta were collected from calves fitted with simple cannulae and continuously infused the milk re-placers into the abomasum. The distribution of molecular mass (M_r) of proteins and peptides was studied by gel filtration chromatography. Increasing the dietary CP level of milk replacers increased the flow of oligopep-tides and free amino acids in ileal digesta. Incorporating plant protein increased the flow of proteins with M_r > 20,000 in the duodenum and that of proteins and peptides with M_r < 10,000 in the ileum. Hydrolysis of oligo-peptides and absorption may be a limiting step in the digestion of plant protein in the veal calf.