Seasonal variations in composition and function of gut microbiota in grazing yaks: Implications for adaptation to dietary shift on the Qinghai-Tibet plateau

Gut microbiome of animals is affected by external environmental factors and can assist them in adapting to changing environments effectively. Consequently, elucidating the gut microbes of animals under different environmental conditions can provide a comprehensive understanding of the mechanisms of their adaptations to environmental change, with a particular focus on animals in extreme environments. In this study, we compared the structural and functional differences of the gut microbiome of grazing yaks between the summer and winter seasons through metagenomic sequencing and bioinformatics analysis. The results indicated that the composition and function of microbes changed significantly. The study demonstrated an increase in the relative abundance of Actinobacteria and a higher ratio of Firmicutes to Bacteroidetes (F/B) in winter, this process facilitated the adaptation of yaks to the consumption of low-nutrient forages in the winter. Furthermore, the network structure exhibited greater complexity in the winter. Forage nutrition exhibited a significant seasonal variation, with a notable impact on the gut microbiota. The metagenomic analysis revealed an increase in the abundance of enzymes related to amino acid metabolism, axillary activity, and mucin degradation in the winter. In conclusion, this study demonstrated that the gut microbiome of grazing yaks exhibits several adaptive characteristics that facilitate better nutrient accessibility and acid the host in acclimating to the harsh winter conditions. Furthermore, our study offers novel insights into the mechanisms of highland animal adaptation to external environments from the perspective of the gut microbiome.