Fermented and extruded wheat bran in piglet diets: impact on performance, intestinal morphology, microbial metabolites in chyme and blood lipid radicals

The aim of the present study was to evaluate the influence of native, fermented and extruded wheat bran on the performance and intestinal morphology of piglets. Additionally, short-chain fatty acids (SCFA), biogenic amines, ammonia, lactic acid, pH as well as E. coli and lactic acid bacterial counts were analysed in digesta samples from three gut sections. Furthermore, the antioxidant potential in blood samples was evaluated based on the lipid radicals formed. For this purpose, 48 newly weaned piglets (28 d old) were allocated to one of the four different dietary treatment groups: no wheat bran (Control), native wheat bran, fermented wheat bran as well as extruded wheat bran. Wheat bran variants were included at 150 g/kg into the diets. All diets were mixed to reach the calculated isonitrogenic nutrient contents. Gut tissue and digesta samples were collected from the proximal jejunum, the terminal ileum and the colon ascendens, blood samples directly at slaughter. Although none of the dietary interventions had an impact on performance parameters, the amount of goblet cells in the ileum was increased upon feeding native and extruded wheat bran, compared to fermented bran (p < 0.05). The E. coli counts in colonic chyme were significantly lower (p < 0.05) in the Control group compared to the groups fed with wheat bran. The concentration of SCFA showed differences for minor compounds (p < 0.05), while linear contrast analyses revealed a reduced concentration of total SCFA in the colon following the feeding of modified wheat bran compared to native wheat bran. This may suggest that several compounds are more easily digested already in the ileum, resulting in a reduced nutrient flow into the large intestine and therefore less unexploited digesta is available as substrate for the microorganisms there. Fermentation also resulted in a significant decrease of methylamine in the colon (p < 0.05), while other biogenic amines in the ileum and colon showed no statistically significant differences. The formation of lipid radicals was decreased (p < 0.05) after feeding native wheat bran compared to the Control group. These results suggest that fermentation and extrusion of wheat bran exert some different impact regarding their physiological mode of action.