A Comparative Review of Fertility and Semen Assessment Techniques in Farm Animals

This review provides a comparative examination of current methods for evaluating fertility and semen quality in mammals, with emphasis on livestock species. It is based on a structured search and analysis of 316 academic publications retrieved from major scientific databases, including Elsevier, Springer, Taylor & Francis, and MDPI, as well as other repositories, covering literature published between 1938 and 2025. This review examines advanced semen analysis techniques, including computer-assisted semen analysis (CASA) systems and assays for assessing chromatin integrity, DNA damage, seminal plasma composition, sperm membrane proteins, and functional parameters such as migration capacity, membrane integrity, acrosomal status, capacitation, morphology, viability, concentration, motility, and volume. Methods for semen collection are also outlined. The synthesis focuses on the comparative assessment of techniques and recent findings for major ruminant and monogastric livestock species: cattle (<i>Bos taurus</i> and <i>Bos indicus</i>), buffalo (<i>Bubalus bubalis</i>), sheep (<i>Ovis aries</i>), goats (<i>Capra hircus</i>), and pigs (<i>Sus domesticus</i>). A brief historical overview of assisted insemination is presented, incorporating relevant procedures and managerial factors that affect fertility outcomes. Advances in genetics related to reproductive health are also discussed. This synthesis seeks to integrate existing knowledge and guide future research in reproductive science for both animal production and human medicine.