Ruminal bacterial diversity of yaks (Bos grunniens) fed by grazing or indoor regime on the Tibetan Plateau by analysis of 16S rRNA gene libraries

This study was conducted to investigate the ruminal bacterial diversity of yaks (Bos grunniens) fed by grazing or indoor regime on the Tibetan Plateau by analysis of 16S rRNA gene libraries. A total of 18 healthy Sibu male yaks (118±17 kg body weight) were randomly assigned to either indoor-feeding group (A) or grazing group (B). At the end of the 135-day experiment, ruminal bacterial diversity was analysed by using 16S rRNA gene clone libraries. A total of 212 clones were obtained from two libraries, divided into 162 operational taxonomic units (OTUs). Two libraries shared 13 OTUs. Ruminococcus albus, Ruminococcus flavefaciens and Butyrivibrio fibrisolvens were detected in both libraries. Whereas, Selenomonas ruminantium, Succiniclasticum ruminis, and Butyrivibrio proteoclasticus emerged only in library B, and Pseudo-butyrivibrio ruminis and Roseburia faecis appeared only in library A. A total of 73 out of 86 OTUs (84.88%) in library A and 65 out of 89 OTUs (73.03%) in library B fell into the phyla of low G+C subdivision, the remaining clones mainly belonged to the cytophaga/flexibacteria/ bacteroites subdivision in the two different libraries. In conclusion, different feeding patterns (indoor-feeding or grazing) had an effect on rumen bacterial diversity in yaks.