Metagenomic and metabolomic analyses of rumen fiber digestion in Mongolian cattle fed fresh grass versus hay

Abstract

Mongolian cattle’s superior roughage tolerance depends on a specialized rumen microbiome that degrades fibrous substrates via diverse CAZymes. However, microbe-metabolite interactions driving fiber digestion in this breed remain poorly understood. This study revealed an increased abundance of bacteria and fungi involved in rumen fiber degradation, which may be responsible for secreting enzymes associated with hemicellulose and pectin breakdown. Furthermore, the upregulation of key metabolites, including gluconolactone, indirectly promotes acetate production through pathways such as glycolysis and the pentose phosphate pathway. These findings reveal microbial adaptations enhancing low-quality forage utilization, offering new strategies for improving ruminant efficiency in seasonal or resource-limited grazing systems.