Live Promotes Rumen Fermentation by Modulating Rumen Microbiota In Vitro.

Previous studies have shown that affects rumen fermentation and rumen microbial community structure, which are limited to detect a few microbial abundances using traditional methods. However, the regulation of on rumen microorganisms and the mechanisms of microbiota that affect rumen fermentation is still unclear. This study explored the effects of live and autoclaved on ruminal microbial composition and diversity in vitro using 16S rRNA gene sequencing and the underlying mechanisms. Rumen fluid was collected, allocated to thirty-six bottles, and divided into three treatments: CTR, blank control group without ; LBS, CTR with 10 cfu of live ; and ABS, CTR with 10 cfu of autoclaved . The rumen fluid was collected after 0, 6, 12, and 24 h of fermentation, and pH, ammonia nitrogen (NH-N), microbial protein (MCP), and volatile fatty acids (VFAs) were determined. The diversity and composition of rumen microbiota were assessed by 16S rRNA gene sequencing. The results revealed LBS affected the concentrations of NH-N, MCP, and VFAs ( < 0.05), especially after 12 h, which might be attributed to changes in 18 genera. Whereas ABS only enhanced pH and NH-N concentration compared with the CTR group ( < 0.05), which might be associated with changes in six genera. Supplementation with live improved ruminal NH-N and propionate concentrations, indicating that live bacteria were better than autoclaved ones. This study advances our understanding of in promoting ruminal fermentation, providing a new perspective for the precise utilization of in dairy rations.