Dietary supplementation with Bacillus mixture promotes the gut health of weaned piglets

This study was conducted to investigate the effects of dietary supplementation with a mixture of Bacillus on intestinal health in weaned piglets. We randomly assigned 120 piglets to a control group (basal diet), a probiotics group (supplemented with 4×109 CFU/g Bacillus licheniformis-B. subtilis mixture (BLS mix)), and a antibiotics group (supplemented with 0.04 kg/t virginiamycin, 0.2 kg/t colistin, and 3000 mg/kg zinc oxide). All groups had five replicates with eight piglets per replicate. On days 7, 21, and 42 of the trial, intestine and digesta samples were collected for determining the intestinal morphology, gut microbiota and metabolites, and expression of genes related to the intestinal barrier function. The results showed that the BLS mix decreased the jejunum crypt depth while increased the ileum villus height and jejunum and Ileum ratio of villus height to crypt depth. In addition, the BLS mix increased the expression level of E-cadherin and Occludin in the colon and pro-inflammatory cytokine and TLR4 in ileum and colon. The BLS mix also increased Simpson's diversity index in the gut microbiota and the relative abundances of o_Bacteroidetes and f_Ruminococcaceae, while decreased the relative abundances of Blautia, Treponema, and Clostridium. Collectively, these findings suggested that dietary BLS mix supplementation efficaciously promotes intestinal development and health through modulation of gut microbiota in weaned piglets.