Vitamin E alters the fecal microbial community in dairy cows with subacute rumen acidosis induced by a high-concentrate diet

Abstract:

[Objective] This study aims to observe the changes of the fecal microbial communities in the dairy cows with subacute rumen acidosis (SARA) induced by a high-concentrate diet and modulated by the addition of vitamin E (VE). The potential effects on the metabolism of dairy cows were evaluated to provide data for exploring the physiological mechanisms of SARA. [Methods] Seven multiparous Holstein cows with rumen fistulas were selected for this trial which was carried out in three phases of 18 days each. The first phase was the control (CON) phase, with a concentrate-to-forage ratio of 50:50 in the diet (dry matter basis). The second phase was the induction (HG) phase, in which the forage was replaced with wheat flour at 15% of the diet (dry matter basis) to induce SARA. The third phase was the regulation (HGE) phase, in which VE was added at 12 000 IU/d/cow on the basis of the diet in the HG phase. The feces samples were collected on day 18 in each phase, and the microbial communities in the samples were examined. [Results] The fecal microbial community structure showed significant differences between three phases and the Shannon index in the HG phase was lower than that in the CON phase (P<0.05). The HG phase had higher relative abundance of Proteobacteria and Blautia and lower relative abundance of unidentified_bacteria, Euryarchaeota, Desulfobacterota, Rikenellaceae_RC9_gut_group, and Alistipes than the CON phase (P<0.05). The relative abundance of Blautia in the HGE phase was higher than that in the HG phase (P<0.05). The functional prediction results showed that SARA caused metabolic disorders in the dairy cows, while VE regulated the intestinal microbiota and health by improving the stability of microbial growth and promoting microbial reproduction. [Conclusion] The SARA induced by a high-concentrate diet led to reduced intestinal microbial diversity and metabolic disorders in dairy cows. VE can regulate intestinal health and maintain intestinal homeostasis by promoting the proliferation of beneficial intestinal microorganisms.

Key words:dairy cows;subacute ruminal acidosis;vitamin E;feces;microorganisms