Evaluation of cultivable aerobic vaginal microbiota of repeat breeder and healthy pregnant dairy cows

Abstract

Objective: Vaginal microbiota on bovine fertility has been minimally explored, and data on this are limited, despite the fact that vagina itself is a first barrier against ascending pathogens in the reproductive tract and interacts with host mucosa. Contamination of the female genital tract or dysbiosis of the vaginal flora have risks for the development of reproductive problems. Subclinical endometritis is one of the many variables that might lead to repeat breeder syndrome, and its significance has been neglected. In this study, we aimed to examine cultivable aerobic vaginal microbiota of repeat breeder (RB) cows and healthy pregranant (HP) cows at 60th day following artificial insemination. Methods: A total of 45 Holstein breed dairy cows aged between 3 and 8 years including 20 repeat breeder (RB) cows (Group I = RBG), alongside 25 healthy pregnant (HP) cows (Group II=HPG) that conceived within one or two inseminations were used as study groups. The vaginal swab samples collected from RBG and HPG were incubated at 37 °C for 24 hours in fluid thiogly-collate. On the next day, part of the initial culture was inoculated onto blood agar and EMB agar examined for the cultivable vaginal microbiota. The identification of bacteria was done with an automated system. Results: A total of 26 species of 16 genera distributed among 4 phyla including Proteobacteria, Firmicutes, Actinobacteria, Bacteroiodetes were identified. The relative abundance of Proteobacteria in HP group comparing with the RB group was associated with an increase in progesterone. HP group presented relatively greater richness with 21 species followed by the RB group with 17 identified species. HP group possessed a more diverse microbiota in comparison to those suffering from subclinical endometritis. The relative abundance of Escherichia genus and Escherichia coli in RB group might have induced supressing the release of luteinizing hormone. Conclusion: As a conclusion, the diversity of the vaginal microbiota and numerically abundance of some genus and species had favourable/unfavorable effects on reproductive fertility. The consortium of vaginal microbiota should be explored entirely in further studies since vagina is the first entrance of pathogens via ascending route in the reproductive tracts.