Abstract：To investigate the effect of feeding Bacillus subtilis natto on the structure of Holstein calves rumen bacterial community, eight calves were randomly assigned into two groups: a group fed with starter (control), and another group supplemented with Bacillus subitilis natto N1 (1×1010 CFU), which was mixed with starters at a dose of 1% of the daily dry matter intake. DNA from rumen samples were extracted and two rumen 16S rDNA libraries were constructed. The results showed that the vast majority of the two clone libraries were represented by sequences related to the Bacteroidetes and Firmicutes. Of the two clone libraries, the diversity index was high, and the ACE and Chao1 collector’s curves didn’t reach the stable libraries were represented by sequences related to the Bacteroidetes and Firmicutes. Of the two clone libraries, the diversity index was high, and the ACE and Chao1 collector’s curves didn’t reach the stable trend. There was significant difference between the structure of 16S libraries from control and treatment group. Real-time PCR quantification of Ruminobacter albus and Ruminococcus flavefaciens showed that we can detect the Ruminococcus flavefaciens in TRT group, but not in CK group. Compared with CK group, Ruminobacter albus increased to 11.3% in TRT group. These results indicated that feeding Bacillus subtilis natto to Holstein calves could promote the establishment of rumen microbial community, especially the colonization and growth of fiber degradation-related bacteria.
