Protein digestion of leguminous in monogastrics. Pea proteins as an example

Abstract

Present knowledge of protein digestion in monogastrics, mainly pig and poultry, is reviewed. Peas, an important protein-rich European crop, is chosen as an example because of the high variability of digestibility of the proteins of this feedstuff. After recalling pea protein composition and digestibilities in monogastrics, various compounds potentially implied in explaining the observed results, are presented. Thus antinutritional factors of this leguminous can have negative effect. Other pea or diet compounds such as saccharides or lipids may be implied. Moreover, protein structure leads to various susceptibilities to hydrolysis. Thus some characteristics, suchas an important hydrophobicity, high glycosylation level, secondary structure rich in β-sheets, compact tertiary structure and disulphide bonds seem to have a negative impact on protein hydrolysis. Technological processings applied on the diet may affect protein digestion. Thus, grinding can increase digestion. Likewise thermal processings such as pelleting or extrusion, in so far as used conditions are not extreme, can improve protein digestion.

Thus excreted nitrogen from a digestive origin depends on several factors. This nitrogen loss is composed of proteins and peptids also, whose origin must be determined (feed or endogen) in order to suggest solutions to decrease it.