Changes in rumen microbial community composition in yak in response to seasonal variations

Yak is a dominant ruminant that adapted to the environment of the 3000 meter-high Qinghai–Tibet Plateau.The complex microbiota that resides within the yak rumen is responsible for fermentation and thus might help in adaption. In the present study, we performed 16s rRNA gene sequencing to investigate the seasonal variations in microbial communities in yak rumen. Results showed that the bacterial communities were strongly dominated by Bacteroides (72.13%–78.54%) and Firmicutes, and the abundance of Firmicutes was higher in summer (17.44%) than in winter (10.67%; P < 0.05). The distribution differed among spring, summer, and winter (PERMANOVA, P = 0.001). The highest total volatile fatty acid concentration in the yak rumen was obtained in summer (P < 0.05), followed by the volatile fatty acid concentrations in spring and winter. The positive and inverse correlations of different genera with volatile fatty acid were indicated. We found that microbial communities in yaks highly respond to seasonal variations. Considering environmental factors, we suggest that the adaptation of microbial communities in rumen enables their hosts to overcome seasonal changes, especially in the cold seasons (spring and summer).