Changes in the diversity and composition of gut microbiota of weaned piglets after oral administration of Lactobacillus or an antibiotic.

The gut microbiota plays important roles in the health and well-being of animals, and high-throughput sequencing facilitates exploration of microbial populations in the animal gut. However, previous studies have focused on fecal samples instead of the gastrointestinal tract. In this study, we compared the microbiota diversity and composition of intestinal contents of weaned piglets treated with Lactobacillus reuteri or chlortetracycline (aureomycin) using high-throughput sequencing. Nine weaned piglets were randomly divided into three groups and supplemented with L. reuteri, chlortetracycline, or saline for 10 days, and then the contents of three intestinal segments (jejunum, colon, and cecum) were obtained and used for sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The microbiota diversity and composition in the jejunum were different from those in the colon and cecum among the three treatments. In the jejunum, treatment with L. reuteri increased the species richness of the microbiota, as indicated by the ACE and Chao1 indexes, compared with the chlortetracycline group, in which several taxa were eliminated. In the colon and cecum, relative abundances of the phylum Firmicutes and the genus Prevotella were higher in the chlortetracycline group than in the other groups. Distances between clustered samples revealed that the L. reuteri group was closer to the chlortetracycline group than the control group for jejunum samples, while colon and cecum samples of the L. reuteri group were clustered with those of the control group. This study provides fundamental knowledge for future studies such as the development of alternatives to antibiotics.