Weaned piglets display low gastrointestinal digestion of pea (Pisum sativum L.) lectin and albumin pea albumin 2

¹ INRA, UMR 1079, Systèmes d'Elevage, Nutrition Animale et Humaine, Domaine de la Prise, 35590 Saint-Gilles, France; INRA, Unité de Recherche Biopolymères, Interactions, Assemblages, Rue de la Géraudière, 44072 Nantes, France
² INRA, Unité de Recherche Génétique et Ecophysiologie des Légumineuses à graines, Domaine d'Epoisses, Bretenières, 21065 Dijon, France
³ INRA, UMR 1079, Systèmes d'Elevage, Nutrition Animale et Humaine, Domaine de la Prise, 35590 Saint-Gilles, France
⁴ INRA, Unité de Recherche Biopolymères, Interactions, Assemblages, Rue de la Géraudière, 44072 Nantes, France

^* To whom correspondence should be addressed. E-mail: Maud.LeGall{at}rennes.inra.fr.

	Abstract

A study was conducted to investigate the biochemistry of digestion of field pea (Pisum sativum L.) albumins and globulins in the stomach and along the small intestine of weaned piglets with a particular emphasis on the respective roles of these compartments in pea protein digestion. Twenty four piglets were weaned at 28 d of age. They were allocated to 2 diets (control and pea) and 3 slaughter times (3, 6, or 9 h after the last meal) in a 2 xx3 factorial arrangement of treatments in a randomized complete block design. Pea flour provided 30% of total dietary protein in the pea diet. The diets were fed for 2 wk after weaning. After slaughter, gastrointestinal tract compartments were weighed, digesta collected, and pH measured. Digesta from the stomach and proximal, mid, and distal small intestine (SI) were extracted for soluble proteins and analyzed for specific pea proteins using SDS-PAGE, immunoblotting, and mass spectrometry. Tissue weight of the whole gastrointestinal tract (GIT; P = 0.015), cecum (P < 0.001), and colon (P < 0.001) was greater in the pea diet. Digesta pH in the stomach and distal SI was lower (P = 0.02) in the pea diet than the control diet. In the stomach, vicilin, lectin, and pea albumin 2 (PA2) were not digested, while legumin was only partly digested. Legumin and vicilin were totally digested in the SI in less than 3 h. A resistant peptide of 15 kDa located at the N-terminus of PA2 was transiently detected at 3 h. A protein band at 20 kDa was consistently identified as lectin. It was present in high intensity in intestinal digesta of pea-fed piglets at all times after the meal compared with those fed the control diet (P < 0.001). Various proteins of, presumably, endogenous origin, displayed differential digestion patterns between the control and the pea-fed piglets (P < 0.05). In conclusion, differences in digestion between specific pea proteins were observed along the GIT of piglets. They could be partly explained by differences in protein digestion in the stomach.

Key Words: albumin, digestion, globulin, pea protein, pig