This experiment was conducted to determine the effect of Bacillus subtilis natto fermentation product supplementation on blood metabolites, rumen fermentation and milk production and composition in early lactation dairy cows. Thirty-six multiparous Holstein cows (DIM = 29 ± 6 days, parity = 2.8 ± 1.1) were blocked by DIM and parity and then randomly assigned to three treatments (12 per treatment) in a 9-week trial. Cows in control, DFM1 and DFM2 were fed TMR diets supplemented with 0, 6 and 12 g of B. subtilis natto solid-state fermentation product per day per cow respectively. Plasma non-esterified fatty acids were lower (p = 0.03) in DFM1 and DFM2 compared with control cows (633 and 639 vs. 685 μm). Ruminal propionate increased (23.9 vs. 26.3 and 26.9/100 mol, control vs. DFM1 and DFM2 respectively) and acetate decreased (64.2 vs. 62.7 and 62.1/100 mol, control vs. DFM1 and DFM2 respectively) with increasing B. subtilis natto fermentation product supplementation. DMI of the cows in three treatments was not affected by B. subtilis natto fermentation product supplementation, but milk yield was 3.1 and 3.2 kg/day higher for DFM1 and DFM2 than that for control cows on average across the 9-week trial, and significant differences were observed during weeks 5-9 of the trial, which resulted in 9.5% and 11.7% increase in feed efficiency. B. subtilis natto fermentation product supplementation did not affect milk fat percentage and protein yield but increased (p < 0.05) milk fat yield and lactose percentage (p < 0.01) and tended to decrease protein percentage (p = 0.06). The findings show that B. subtilis natto fermentation product was effective in increasing lactation performance of early lactation dairy cows possibly by altering the rumen fermentation pattern without any negative effects on blood metabolites.

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Endometritis is an important disease of dairy cows that leads to significant economic losses in the dairy cattle industry. To investigate the alteration of proteins associated with endometritis in the dairy cow, the isobaric tags for relative and absolute quantification (iTRAQ) technique was applied to quantitatively identify differentially expressed proteins (DEP) in the endometrium and peripheral plasma of Chinese Holstein cows with endometritis. Compared with the normal (control) group, 159 DEP in the endometrium and 137 DEP in the plasma were identified in cows with endometritis. Gene ontology analysis demonstrated that the predominant endometrial DEP were primarily involved in responses to stimulus and stress processes and mainly played a role in hydrolysis in the extracellular region. The predominant plasma DEP were mainly components of the cytosol and non-membrane-bound organelles, and they were involved in the response to stress and regulation of enzyme activity. Protein-protein interaction of tissue DEP revealed that some core seed proteins, such as RAC2, ITGB2, and CDH1 in the same network as CD14, MMP3, and MMP9, had important functions in the cross-talk of pathways related to extracellular proteolysis. In summary, significant enzymatic hydrolase activity in the extracellular region is proposed as a molecular mechanism by which altered proteins may promote inflammation and hence endometritis.