Dynamic changes in rumen fermentation, microbial communities, and metabolite profiles of non-pregnant and gestational Ashidan yaks

Rumen microbiota and their metabolites in ruminants across reproductive stages benefit the animals' growth, health and offspring's development. However, the impact of rumen fermentation profiles, microbial composition, and metabolite dynamics between non-pregnant and gestating Ashidan yaks remains poorly understood. This study analyzed the rumen fermentation, metagenome and metabolome of five 2-3-year-old Ashidan yaks during the non-pregnant period (NP; 11-30 days pre-mating) and the gestational period (GP; 112-148 days post-conception). Research has found that gestation had higher acetic acid and ammonia nitrogen (NH₃-N) (P < 0.05), increased Ascomycota, Apicomplexa, Rhodococcus, Acinetobacter, Methanosphaera (P < 0.05); differential metabolites enriched in valine, leucine, isoleucine biosynthesis and histidine metabolism (P < 0.05), with L-threonine and urocanic acid as major ones. Additionally, microorganisms, metabolites and fermentation parameters correlated. The study shows Ashidan yaks adapt to reproductive stages via regulating rumen microbiota and metabolism, providing a basis for feeding management.