Microbiota and reproduction in agricultural mammals (review)

The use of specialized animal breeds of agricultural species is often accompanied by a decrease in reproductive success. In dairy cattle breeding, the number of service-period days, artificial insemination procedures per pregnancy, and the frequency of pregnancy losses are increasing (S.V. Guskova et al., 2014). Accumulated data on obtaining embryos by in vivo and in vitro methods and their transplantation indicate a significant level (30-60 %) of embryo losses (P.J. Hansen, 2020). The reasons for low rates in reproductive technologies are diverse and associated with both biotic and abiotic factors, and one of the key factors of embryo losses may be the imbalance of microbial communities in the reproductive system sections of both female donors and recipients. The study of the microbiota composition of various departments and systems of the multicellular organism has recently become an increasingly dominant topic in the scientific literature. Modern methods of microbial identification, e.g., metagenomic sequencing, reveals great microbial diversity in various anatomical departments of macroorganisms. The accumulated data show the microbial composition, dynamics in the organs of the reproductive system, and its relationship with the reproduction of mammals, reproductive success, the course of pregnancy, the prognosis of the possibilities of pathological processes. The review focuses on the impact of microbiota on the success of reproductive technologies, e.g., in vitro fertilization, embryo transplantation, and artificial insemination. For example, F. Marco-Jiménez et al. (2020) discuss the effect of symbiotic bacteria on fertility and semen quality. The understudied nature of this area for mammals and the extreme need for additional research on the microbiota of the reproductive tract of farm animals, the results of which will provide insight and insight into the unsuccessful and positive outcomes of reproduction, are noted. At the same time, the practical application of this information will increase the chances of success in reproductive biotechnology, reduce the costs associated with reproduction and therapeutic interventions in the treatment of pathological processes of the reproductive system, and open up the possibility of developing and implementing new methods such as microbial therapy. Thus, it can be concluded that the microbiota of mammalian reproductive system and organs influence the physiological processes of reproduction (R. Koedooder et al., 2019). It is clear that by being able to manage microbial communities, humans can increase the chances of reproductive success in the reproduction of highly specialized breeds of farm animals (P.J. Hansen, 2020; R.W. Hyman et. al., 2012; D.E. Moore et. al., 2000).