| The effects of Bacillus subtilis Natto on gastrointestinal fermentation and microbiota of early lactation Holstein dairy cows were investigated in this study. Twenty-four early lactation Holstein dairy cows were randomly allotted to two treatments:with (0.5×1011CFU Natto/d, DFM) and without (Control, CON) B. subtilis Natto (DFM). All cows were treated with two treatments after adaption feeding period of 14 days, and the whole trail lasted for 10 weeks. The supplementation of B. subtilis Natto was top-dressed to each cow on morning feeding TMR. Fecal samples were collected directly from the rectum of each animal at 0,1,2,3,4,6 and 8 wk of feeding, and rumen fluid was collected at 8 wk via oral lavage 2 h after morning feeding. The pH, NH3-N, and VFA concentration of rumen and fecal samples were measured, and fecal total DNA was extracted and analyzed by PCR-DGGE.The results showed that dietary supplementation of B. subtilis Natto to lactating cow trended to increase rumen propionate (P= 0.10) and pentanoate (P=0.06) concentration, but no effects on rumen pH, NH3-N and other VFAs. Fecal NH3-N, pentanoate, and isovaleric acid concentration were significantly (P<0.05) deceased after B. subtilis Natto supplementing, but no effect on fecal pH value. DGGE profile revealed that B. subtilis Natto had some effects on fecal bacteria population. The diversity index of Shannon-Wiener in DFM decreased significantly (P<0.05) compared to Control. Fecal Alistipes sp., Clostridium sp., Roseospira sp., beta proteobacterium decreased, while Bifidobacterum increased after supplementing of B. subtillis Natto.This study demonstrated that B. subtilis Natto had no negative effects on rumen fermentation, but could reduce fecal noxious gas emission by improving hindgut microbiota balance. However, further research need to be conducted to indentify the mechanism regarding B. subtilis Natto to gastrointestinal fermentation. |
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