Yeast Culture Enhances Production Performance in Late-Lactation Dairy Cows by Reshaping Rumen Microbiota and Metabolic Pathways

< 0.01). Macrogenomic analysis revealed a YC-mediated restructuring of the rumen microbiota, characterized by an increased relative abundance of Firmicutes and decreased Bacteroidota. Untargeted metabolomic profiling identified significant alterations in rumen metabolite profiles, with differential metabolites enriched in pyrimidine metabolism and vitamin digestion and absorption pathways. These results indicate that YC supplementation improves production performance in late-lactation dairy cows through multi-faceted mechanisms involving rumen microbial community modulation and metabolic pathway activation, ultimately enhancing nutrient utilization and metabolic efficiency.