Bacterial community in the rumen of Tibetan sheep and Gansu alpine fine-wool sheep grazing on the Qinghai-Tibetan Plateau, China.

The rumen microbiome plays a vital role in ruminant nutrition and health, and its community is affected by environmental factors. However, little is known about the rumen bacterial community of ruminants living in the special ecological environment of the Qinghai-Tibetan Plateau (QTP) of China. The objectives of this study were to investigate the rumen bacterial community of the typical plateau sheep (Tibetan sheep, TS, and Gansu alpine fine-wool sheep, GS) grazing on the QTP, using 16S rRNA gene sequence analysis, and to evaluate the relationship between the rumen bacterial community and the QTP environment. A total of 116 sequences (201 clones) were examined and divided into 53 operational taxonomic units (OTUs) in the TS library and 46 OTUs in the GS library. Phylogenetic analysis showed that the sequences that belonged to the Firmicutes were the most predominant bacteria in both TS and GS libraries, representing 79.4% and 62.8% of the total clones, respectively. The remaining sequences belonged to Bacteroidetes, Proteobacteria, Actinobacteria, or were unclassified bacteria. Sequence analysis revealed that the TS and GS rumens harbored many novel sequences associated with uncultured bacteria that accounted for 63.6% and 46.8% of the total clones, respectively. Comparison of the composition and diversity of the TS and GS rumen bacteria revealed few overlapping known bacteria between the two breeds, and a higher diversity in TS. The rumen bacteria of the plateau sheep showed higher percentages of bacteria that belonged to Firmicutes and novel species compared with the low-elevation sheep. The unique bacterial community in the plateau sheep rumens is perhaps one of the major reasons that they can adapt to the harsh plateau environment. These results can help identify the rumen bacterial community of the ruminants in the QTP, and provide bacteria resources and basic data to improve ruminant productivity.