Changes in the rumen microbiome and metabolites reveal the effect of host genetics on hybrid crosses.

The rumen microbiota plays important roles in nutrient metabolism and absorption of the host. However, it is poorly understood how host genetic variation shapes the community structure of the rumen microbiota and its metabolic phenotype. Here, we used sika deer (Cervus nippon) and elk (Cervus elaphus) to produce the following two types of hybrid offspring: sika deer ♀ × elk ♂ (SEH) and elk ♀ × sika deer ♂ (ESH). Then, we examined the rumen microbiome and metabolites in the parents and their hybrid offspring. The rumen microbiota in the hybrids differed from that in their parents, suggesting a significant effect of host genetics on the rumen microbiome that may have resulted from vertical transmission. The rumen metabolites displayed patterns similar to the structure of the rumen microbiome, with changes in the amounts of volatile fatty acids and metabolites of amino acids. The alanine, arginine, proline and phenylalanine pathways were enriched in the rumen of hybrid animals. The enriched metabolites in the above pathways were positively correlated with the bacteria Prevotella spp., Acetitomaculum spp., Quinella spp., Succinivibrio spp. and Ruminobacter spp. These results suggest that host genetics has a major impact on the rumen microbiome and metabolites in hybrid animals.