Abstract:

The purpose of this paper was to study the change rule with the seasons of rumen bacterial flora structure and diversity of Mongolian sheep grazed on typical grasslands in Northern China.In the experiment, six Mongolian sheep grazed all year round and no supplementary feeding were randomly selected from the typical grasslands of Northern China.In winter (January), spring (April), summer (June grass growth stage and August grass vigorous stage) and autumn (October), the rumen juice of the sheep was extracted through the mouth, and in every season the structure and diversity of rumen bacterial flora were analyzed by MiSeq sequecing technology.The results showed that there were the highest operational taxonomic unit (OTU) and diversity of the rumen bacteria of grazing Mongolian sheep in summer grass vigorous stage and the lowest in winter, and there were significant differences in OTU and diversity between summer and winter (P<0.05).At the phylum level, Firmicutes (56.93%) and Bacteroidetes (21.52%) were the dominant bacterial populations in the rumen of Mongolian sheep.The OTU of Firmicutes reached its maximum in August and that of Bacteroidetes reached its maximum in June, which were significantly different from other months.At the family level, Ruminococcaceae (19.09%), Lachnospiraceae (16.98%), Christensenellaceae (12.11%), Prevotellaceae (8.51%) and Rikenellaceae (8.27%) were the dominant bacterial populations in the rumen of Mongolian sheep, respectively reaching the peak in summer (June or August).At the generic level, rumen bacteria of the highest contents were respectively Prevotella (4.79%), Butyrivibrio (1.77%) and Ruminococcus (1.27%).So Ruminococcaceae of Firmicutes had the highest number of rumen bacteria of grazing Mongolian sheep in Northern China, which was a typical cellulose-digestive bacterium and in accord with the characteristics of grazing sheep fed with forage grass.

Key words: Mongolian sheep; rumen bacterial; MiSeq sequencing; seasonal variation; diversity