Co-fermented defatted rice bran alters gut microbiota and improves growth performance, antioxidant capacity, immune status and intestinal permeability of finishing pigs.

Based on preparation of co-fermented defatted rice bran (DFRB) using , , and phytase, the present study aimed to evaluate the effects of co-fermented DFRB on growth performance, antioxidant capacity, immune status, gut microbiota and permeability in finishing pigs. Ninety finishing pigs (85.30 ± 0.97 kg) were randomly assigned to 3 treatments (3 replicates/treatment) with a basal diet (Ctrl), a basal diet supplemented with 10% unfermented DFRB (UFR), and a basal diet supplemented with 10% fermented DFRB (FR) for 30 d. Results revealed that the diet supplemented with FR notably ( < 0.05) improved the average daily gain (ADG), gain to feed ratio (G:F) and the digestibility of crude protein, amino acids and dietary fiber of finishing pigs compared with UFR. Additionally, FR supplementation significantly ( < 0.05) increased total antioxidant capacity, the activities of superoxide dismutase and catalase, and decreased the content of malonaldehyde in serum. Furthermore, FR remarkably ( < 0.05) increased serum levels of IgG, anti-inflammatory cytokines (IL-22 and IL-23) and reduced pro-inflammatory cytokines (TNF-α, IL-1β and INF-γ). The decrease of serum diamine oxidase activity and serum D-lactate content in the FR group ( < 0.05) suggested an improvement in intestinal permeability. Supplementation of FR also elevated the content of acetate and butyrate in feces ( < 0.05). Moreover, FR enhanced gut microbial richness and the abundance of fiber-degrading bacteria such as and . Correlation analyses indicated dietary fiber in FR was associated with improvements in immune status, intestinal permeability and the level of butyrate-producing microbe , which was also verified by the in vitro fermentation analysis. These findings provided an experimental and theoretical basis for the application of fermented DFRB in finishing pigs.