Effects of Lactobacillus plantarum and Saccharomyces cerevisiae on rumen fermentation parameters, microbial diversity and metabolites of fermented feed in vitro

This study was conducted to investigate the effects of Saccharomyces cerevisiae (SC) and Lactobacillus plantarum (LP) on rumen fermentation, rumen microflora and rumen microbial metabolism by using SC and LP to ferment crop processing by-products. Treatments were as follows: Control (fermented feed); SC group (Saccharomyces cerevisiae addition group); LP group (Lactobacillus plantarum addition group); SCLP group (Saccharomyces cerevisiae and Lactobacillus plantarum addition group). The treatment groups were subjected to in vitro rumen fermentation for 48 h using fermentation bags. The results demonstrated that supplementing with SC, LP, and SCLP decreases NDF and ADF concentrations, with SC and SCLP also exhibiting a notable increase in crude protein (CP) content. The abundance of nutrient degrading bacteria such as Spirochaetes and Fibroatheroma in the rumen microbiota of the SCLP group increased, facilitating more effective breakdown and uptake of essential nutrients. Compared with the CON, in the LP group and SCLP group, the metabolites of the Glycine/serine/threonine metabolism pathways, Protein digestion and absorption pathways, and Aminoacyl-tRNA biosynthesis pathway were up-regulated. Moreover, the metabolites of vitamin digestion and absorption pathways and mineral absorption pathways were significantly up-regulated. In conclusion, the synergistic effect of using Saccharomyces cerevisiae and Lactobacillus plantarum fermented feed can improve the nutritional level of fermented feed, regulate the rumen environment, and enhance the digestion and utilization of feed.