lleal non digested proteins were identified in piglets fed a casein control diet or diets based on legume grains. Mathematical approach indicated that with the casein diet ileal digesta contained 30% of casein, and host and bacterial proteins approximately in equal proportions (35%). With legume diets, 22-31% of ileal protein corresponded to casein, the host and bacterial protein were 35-53% and 14-48%, respectively. The proportion of non digested legume proteins was low. Three major ileal endogenous proteins, more present in piglets fed the legume-based diets, shared AA sequences with the trypsin (25 kDA) and coagulation factor IX or chymotrypsin (27 and 30 kDa).