Studies have found that a dietary supplement of Bacillus amyloliquefaciens improved the growth performance, increased the nutrient digestibility of hosts and modulated the intestinal microflora. A total of 360 1-day-old Ross broilers were randomly divided into three treatments: a control group with a basal diet, an antibiotic group with a basal diet and added colistin sulphate, and a probiotics group with a basal diet and added Bacillus amyloliquefaciens. The HiSeq high-throughput sequencing analysis of 16S rRNA was used to investigate the differences in birds' caecal microflora, and metabolomics was used to analyse changes in caecal metabolites. Results showed that the supplementation of Bacillus amyloliquefaciens significantly improved the BW and ADG compared with the control birds. Results of sequencing indicated that (i) 645, 670, 596 unique operational taxonomic units (OTUs) were found in birds supplemented with Bacillus amyloliquefaciens on day 7, 21 and 42, separately, (ii) due to the diversity and relative abundance of the birds' caecal microflora, the OTUs of the caecal microflora clustered according to age and treatment, except on day 42, (iii) among the six predominate families (Ruminococcaceae, Lachnospiraceae, Enterobacteriaceae, Erysipelotrichaceae, Lactobacillaceae and Rikenellaceae), the supplementation of Bacillus amyloliquefaciens significantly increased Enterobacteriaceae on day 42, (iv) Bacillus amyloliquefaciens increased the relative abundance of Faecalibacterium and Ruminococcus on day 21, increased the Faecalibacterium and Blautia and decreased the Ruminococcus on day 42. The metabolomics of caecal metabolites showed that the dietary Bacillus amyloliquefaciens changed the caecal metabolites involved of amino acid metabolism and glyceride metabolism, and the antibiotics changed the caecal metabolites that were related to carbohydrates and amino acid metabolism on day 21.

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This trial was conducted to investigate the adhesion of Bacillus amyloliquefaciens to Caco-2 cells, the effects of Bacillus amyloliquefaciens on the mucosal immunity, cecal volatile fatty acids and microbial diversity in broiler chickens. Three hundred and sixty 1-d-old Ross 308 chicks were randomly divided into 3 dietary treatments groups, which birds fed with basal diet, basal diet supplemented with colistine sulfate, and basal diet supplemented with Bacillus amyloliquefaciens. Polymerase chain reaction denaturing gradient gel electrophoresis was used to analyze the change of cecal microflora, and Gas Chromatography was used to analyze the cecal volatile fatty acids. Data showed that: 1) Bacillus amyloliquefaciens had a good adhesion ability to epithelial cells; 2) the supplementation of Bacillus amyloliquefaciens significantly increased the concentration of ileal mucosal secretory IgA and interleukin 6, decreased (P<0.05) the concentration of tumor necrosis factor-; 3) resulted in the change of cecal microbial community, higher levels of acetic acid, methylacetic and isovaleric acid in the birds. Thus, we considered that Bacillus amyloliquefaciens enhanced the mucosal immunity, increased the cecal concentration of major volatile fatty acids and the diversity microflora community in broilers.