Characterization and comparison of the bacterial community between complete intensive and extensive feeding patterns in pigs.

To investigate and compare the gut microbiota structures in complete intensive feeding pattern (CP) and extensive feeding pattern (EP) groups, a total of 20 pigs were divided into two groups and fed the same diet. The fecal microbial composition was profiled using 16S rRNA gene sequencing. Our results showed that seventeen predominant genera were present in each pig sample and constituted the phylogenetic core of the microbiota at the class level. The abundance of most of the core microbial flora were significantly higher in the CP group than in the EP group (P < 0.05), while the abundance of Gammaproteobacteria was significantly lower in the CP group than in the EP group (P < 0.05). The CP group had significantly greater community diversity, richness, and evenness than the EP group (P < 0.05). Functional prediction analysis indicated that intestinal microbial species potentially led to faster growth and an increased fat accumulation capacity in the CP group; however, disease resistance was weaker in the CP group than in the EP group. In conclusion, EP pigs have a wider range of activity and better animal welfare than CP pigs, which helps reduce the occurrence of diseases and neurological symptoms. To explore the effect of intestinal flora on disease resistance in pigs at the molecular level, Coprococcus, which is a key gut bacterium in the intestine, was selected for isolation and purification and cocultured with intestinal epithelial cells. qPCR was performed to determine the effect of Coprococcus on SLA-DRB gene expression in intestinal epithelial cells. The results showed that Coprococcus enhanced SLA-DRB gene expression in intestinal epithelial cells. The results provide useful reference data for further study on the relationship between intestinal flora and pig disease resistance.