Search for microbiological markers of fertility in bulls in order to develop a biological method for effectively realizing their genetic potential

The fertility of sires (Bos taurus) plays a crucial role in the efficiency of dairy and beef cattle production. Maintaining high and stable reproductive performance in males remains a serious challenge, as a significant proportion of pregnancy failures during artificial insemination are due to subfertility of bulls due to poor ejaculate quality. In the context of intensive livestock farming and the widespread use of assisted reproductive technologies such as artificial insemination, the ejaculate quality of high-value sires directly determines the genetic progress and economic profitability of entire herds. Despite advances in genetics and veterinary science, a significant proportion of subfertility cases remain unexplained by classical physiological explanations.In recent years, increasing attention has been paid to the role of the microbiome in various aspects of animal productivity and health, including reproductive function. The semen microbiota has long remained poorly studied due to the low microbial biomass and the difficulty of culturing the microorganisms present there using traditional methods. Furthermore, classical culture-based microbiological analysis methods have long focused exclusively on identifying pathogens in semen that cause overt infectious diseases.The relevance of studying the semen microbiome using next-generation sequencing (NGS) stems from the need to move from identifying individual pathogens to analyzing the entire microbial ecosystem. Furthermore, studying the relationship between microbial communities and standard indicators of ejaculate quality may reveal new, previously unknown causes of decreased fertility.The goal of the study is to investigate the taxonomic composition and diversity of the microbiome of sires (Bos taurus) ejaculate and to establish its possible relationship with additional parameters of its quality.