Semen liquid microbiome of Bos taurus: taxonomic diversity, impact on fertility, and potential for probiotic modulation

The relevance of studying the microbiome of bull semen is due to the high importance of reproduction in animal husbandry, the problems of semen contamination with pathogens, and the need to improve the efficiency of artificial insemination. This review provides an overview of the taxonomic groups of microorganisms present in the seminal fluid of bulls. The review highlights the reasons for the limited research on the microbiota of bull semen and focuses on the advantages of modern molecular technologies, such as 16S rRNA sequencing, which allow for a more accurate determination of the microbial spectrum and their role in the reproductive system. The microbiota is diverse, including the phyla Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria , and Fusobacteria , which are likely to have a variety of effects on seed quality and fertility. It has been proven that despite the established influence of the reproductive system microbiome on fertility and sperm quality, which has been confirmed by studies on humans and other species of productive animals, there are currently no specific scientific publications that examine in detail the role of the seminal microbiome in bulls and its impact on relevant reproductive indicators. This review explores the external factors that influence the composition of the microbiome, such as feeding, season, and animal management practices. It was concluded that the use of probiotics in the feeding of bulls is a promising and environmentally friendly way to optimize the microbiota and improve reproductive function, increasing the quality of semen and fertility and reducing the need for antibiotics.