No abstract

Background: Using 16s rRNA sequencing of the V3-V4 hypervariable region, the present study is aimed to check vaginal microbiota diversity throughout different stages of the estrous cycle, with attention to hormonal changes and microorganism diversity. Metagenomic research was conducted on vaginal swab samples obtained from healthy cows' at different stages of the estrous cycle. Results: Total sixteen cows were synchronized with dobble PG regime. Nine cows demonstrated estrus within 96 hours and were eligible for the experiment. Vaginal samples for metagenomics and blood samples for hormonal analysis were collected during estrus, metestrus, diestrus and proestrus of synchronized Estrous cycle. The study's findings revealed that the diestrus phase has a different diversity than the other three estrous cycle phases, implying that hormones affect bacterial diversity. Proteobacteria and Firmicutes are the most abundant phyla at the phylum level, accounting for 94 % of bacterial diversity. Actinobacteriota, Patescibacteria, Cyanobacteria, Bacteroidota, and others are fewer common phyla. Proteobacteria are most common throughout the estrus, metestrus, and proestrus stages of the estrous cycle at the phylum level, there was no discernible distinction between the follicular and luteal phases. After statistical correction, Bacillaceae, Alcaligenes, and Enterobacteriaceae & Morganellacea families are more significant. At the diestrus stage, the Family Enterobacteriaceae is lower than at other stages; otherwise, all statistically significant genera are high at diestrus stages. The luteal phase had higher levels of Micrococcus, Stenotrophomonas, UGC-010, Massilia, and Methylobacillus than the follicular phase, however, statistical analysis revealed no substantial difference between the two phases. Lactobacillus genus is present on two samples including the estrus stage and diestrus stages. Conclusions: This study represents an important step towards the understanding of microbial diversity within different stages of the estrous cycle of the dairy cow. The study results revealed dynamics of metabiota during estrous cycle.