Fecal Microbiota and Diet Composition of Buryatian Horses Grazing Warm- and Cold-Season Grass Pastures

The Buryatian horse is an ancient breed and, as an indigenous breed, they have unique adaptive abilities to use scarce pastures, graze in winter, and survive in harsh conditions with minimal human care. In this study, fecal microbiota of Buryatian horses grazing in the warm and cold seasons were investigated using NGS technology on the Illumina MiSeq platform. We hypothesized that the composition of microbial communities in the feces of horses maintained on pasture would change in the different seasons, depending on the grass availability and different plant diets. We conducted microhistological fecal studies of horse diet composition on steppe pasture. The alpha diversity analysis showed horses had a more abundant and diverse gut microbiota in summer. There were significant effects on the beta diversity of microbial families, which were clustered by the warm and cold season in a principal coordinate analysis (PCoA), with 45% of the variation explained by two principal coordinates. This clustering by season was further confirmed by the significant differences observed in the relative abundances of microbial families and genera. The obtained results can serve as an experimental substantiation for further study of the impact of pasture grasses, which have a pharmacological effect, on the diversity of the gut microbiome and horse health.