goat rumen microbiota after antibiotic administration

In this study, we used 16S rRNA gene sequencing to examine the post effects of antibiotic treatment on the structure and metabolism of rumen microbiota. 12 goats were randomly assigned into two groups, with one group received intramuscular streptomycin injection of 40 mg/kg of bodyweight daily for 10 days. 4 weeks after cases of antibiotic, 3 goats were randomly picked out from each group and switched to a 35% concentrate diet. The remaining six goats continued with the 10% concentrate diet. 4 weeks after dietary shift, ruminal fluid and epithelium were collected to analyze the compositions of microbiota and concentrations of short-chain fatty acids (SCFAs). The results revealed the antibiotic administration led to the increases on the diversity and richness of recovered mucosal microbiota, and the decreases on that of recovered fluid microbiota. When dietary modulation was performed after antibiotic intake, both communities showed the little difference on the structure from the pre-modulated states. Additionally, antibiotic pretreatment reduced the basal lines of individual SCFAs, but did not affect the increased percentages of SCFAs. Overall, our results indicated that antibiotic affected the structures of both rumen fluid and mucosal microbiota, leading to the decrease on rumen fermentation yield.