PSVI-1 - Evaluation of the synergistic effect of iron and an aqueous extract of oak bark on rumen microbiome of cattle

The search for new substances, alternatives to feed antibiotics in animal husbandry, is relevant in connection with the development of antibiotic resistance of pathogenic microorganisms. Substances of plant and mineral origin including nanoforms are of particular interest. The experiment studied the synergistic effect of iron (Fe; d = 80 nm) and an aqueous extract of oak bark (Ex; 1:10) on the microbiome of ruminal fluid of bulls (age 14 months, n = 5). Group I - control; Group II - Ex (0.6 ml / kg / lm); Group III - Fe (0.1 mg/kg/FM) with Ex in the same dosage. The collection of ruminal fluid was performed through a chronic ruminal fistula. Metagenomic analysis of cicatricial fluid was performed on a MiSeq device (Illumina, USA). Analysis of the data showed that the Bacteria domain is more influenced by Ex, there is a decrease by 27.0% (P ≤ 0.05), while in group III by 3.0% relative to the control. At the phylum level, Bacteroidetes and Firmicutes had the greatest importance, in group I their ratio was 39.3 and 54.7%, in group II - 37.7 and 56.4%, in group III - 46.1 and 47.0% of the total the number of bacteria. The use of Ex increases the amount of Bacilli by 14.7 and 13.4 (P ≤ 0.05) % relative to groups I and III. The introduction of the composition Ex and Fe increases Lachnospiraceae - 15.0% and Ruminococcaceae - 8.1% of the total number of microorganisms and reduces Streptococcus relative to other groups by 1.3 and 14.9% (P ≤ 0.05). Thus, the combined use of Ex and Fe affects the numerical value of microorganisms, as well as their ratio in the rumen through inhibition. At the same time, the data obtained require further research, including in vivo experiments. This research was performed with financial support from the RSF (20-16-00088).