Abstract: The aim of this study was to investigate the effects of Clostridium butyricum(CB) on cecal microbiota in broiler chickens based on high-throughput sequencing. A total of 300 one-day-old birds were randomly allotted to 2 groups, representing control (basal diet) and CB-treated group (basal diet+3×10⁷ cfu·kg^-1 CB), 6 replications per group with 25 chickens per replication. All chickens were weighted and cecal contents were collected from 3 male chickens per replication to extract genomic DNA after a 42-d treatment. The V3 and V4 regions in 16S rRNA gene of bacteria were amplified and analyzed based on Illumine Miseq sequencing. Results showed that the feed to gain ratio significantly reduced (P<0.05) in CB treatment. Among all bacterial groups revealed by the interpretable sequences, Firmicutes, Bacteroidetes, Proteobacteria and Tenericutes were the predominant phylum in cecum of chickens. It indicated the trend that the relative abundance of Firmicutes decreased by CB treatment, whereas Bacteroidetes increased. At the genera level, Ruminococcaceae uncultured, Faecalibacterium, Alistipes, Lachnospiraceae_incertae_sedis dominated in cecum. Compared with the control group, administration of CB increased the relative abundance of Faecalibacterium, Alistipes, Bacteroides, Phascolarctobacterium and Butyricicoccus(P<0.05), but decreased the relative abundance of Lachnospiraceae_incertae_sedis, Lachnospiraceae_unclassified, Rikenella, Streptococcus and Blautia(P<0.05). Interestingly, the genera of increasing abundance were major bacteria which produce short-chain fatty acids (SCFAs) in cecum and large intestine. These findings suggested that the addition of CB to diet decreased the feed to gain ratio but increased the abundance of bacteria producing SCFAs in cecum of broiler chickens.

Key words: Clostridium Butyricum, high-throughput sequencing, broiler chicken, microbiota