The High Water-Holding Capacity of Pea Inner Fibers Affects the Ileal Flow of Endogenous Amino Acids in Pigs

Abstract

Pigs were fed protein-free diets containing different pea inner fiber (PIF) isolates (from wrinkled or smooth peas, unprocessed or micronized) or different PIF levels (from 50 to 200 g/kg diet), and the flows of endogenous N and amino acids were measured at the ileum level. The flows were better correlated to the water-holding capacity (WHC) of the diet than to fiber intake (R2 = 0.996 vs 0.76, respectively). The relationship with WHC was of the exponential type, with a high increase when the WHC exceeded 3 g of water/g diet. A similar pattern and correlation (R2 = 0.98) was obtained for the ileal flow of nucleobases (markers of epithelial cells and bacteria), whereas the relationships with crude mucus (R2 = 0.96) and diaminopimelic acid (marker of bacteria, R2 = 0.55) were linear. N retention by pigs fed with 0, 30, 60, or 90 g/kg of dry matter (DM) of the same protein isolates did not differ significantly in pigs receiving a 40 or 160 g of PIF/kg diet, despite significant differences in ileal N and amino acid flows between the two fiber levels (2.0 and 3.1 g of N/kg of DM intake, on average). These results and those of the flow of endogenous N compounds suggest an effect of the swollen fibers on the intestinal wall rather than a disturbance of the digestive processes. Keywords: Pig; ileum; endogenous N; fiber; water-holding capacity