Abstract
Following the rejection of antibiotics, the effectiveness of plant substances and probiotics is actively studied in order to increase the productivity of cattle. The purpose of this study was to evaluate the effect of Quercus cortex extract (1 ml/kg b. w.) (QC) on rumen microbiota and characteristics of fermentation against the background of control (C). It was added separately or with a probiotic (Bifidobacterium adolescentis and Lactobacillus acidophilus; 80.0: 1.0) (QC + Pr) as a substrate to the diets of bulls having rumen fistula (12 months of age, diet - 70% hay, 30% barley grain, within 8 days). The parameters of fermentation (CH4, volatile fatty acids) were analyzed every day during the entire period, and the microbiota of archaea and bacteria (microbes associated with fluid) was analyzed using high-performance sequencing of 16S rRNA gene. The QC was prepared by grinding, extraction in a water bath (30 min., 700C) and filtration. The results of this study showed that the production of propionate was higher (P ≤ 0.05) with the substrate QC + Pr compared to C. Bacterial communities differed in feed substrates: Bacteroidetes relatively prevailed with QC and Pr, just like Proteobacteria with QC + Pr C (P ≤ 0.05). At the level of Prevotellaceae family, dominance was registered with QC and Pr (P ≤ 0.05), as well as in genus Prevotella. Firmicutes tended to decrease in all variants as compared with C, the Lactobacillaceae family - with Pr (P ≤ 0.05), and Clostridia - with QC + Pr. In Pr variant there was an increase in Ascomycota and Saccharomycetaceae (P ≤ 0.05). This study highlights the potential joint use of plant and probiotic substances as a natural feed additive that may play a role in metabolism of propionate, without adverse effect on rumen’s microbiota. This research was performed with financial support from the RSF (16-16-10048).