Effect of wheat bran on the health and performance of weaned pigs challenged with Escherichia coli K88+

The leading cause of post-weaning diarrhoea in pigs is Escherichia coli. Previous studies showed that inclusion of wheat bran (WB) in the diet of weaned pigs decreased the number of pathogenic E. coli in the faeces and reduced the incidence of post-weaning diarrhoea. It is not clear whether it is the WB alone that improves gut health, or whether it is the particle size of the WB that is important. In this experiment we used an E. coli K88+ challenge model to test the importance of supplementing WB and particle size of the WB. A total of 36 individually-housed piglets (17 ± 0.77 d) were assigned randomly to one of four experimental groups. Treatments were: (1) a negative control diet (NC) based on corn, wheat, barley and soybean meal; (2) NC + 4% coarsely milled WB (WBc, 1088 μm); (3) NC + 4% finely milled WB (WBf, 445 μm); and (4) a positive control diet (PC) consisting of the NC diet supplemented with a commercial feed grade antibiotic mix. At 26 d of age, pigs were experimentally infected with 6.2 × 109 cfu/mL of E. coli K88+. Body weight, feed intake, and diarrhoea were monitored. Pigs were euthanized 7 d after infection. Ileal digesta and mucosa were taken for E. coli enumeration and for determination of SCFA and indices for richness and diversity of microbiota. There were no significant differences in ADG, ADFI, and G:F ratio attributable to dietary treatment. Inclusion of WB, either fine or coarse, significantly (P < 0.05) decreased E. coli numbers in the ileal digesta. The use of WBc had an additional benefit because the E. coli K88+ numbers were significantly lower (P < 0.05) and the SCFA in ileal digesta was higher (P < 0.05) compared to WBf. We conclude that both WB per se, and the particle size of WB have an effect on gut health in weaned pigs.