Sperm Recovery and Evaluation in Domestic Species: Challenges and Current Practices

Semen collection is a key step in the development of assisted reproductive technologies (ARTs) in domestic mammals, as the collection method determines the functionality and fertility of the sperm. The artificial vagina or manual collection yields ejaculates similar to those obtained during natural mating, although they require prior training to enable semen collection. When semen collection cannot be achieved using the aforementioned techniques, alternative methods such as electroejaculation may be employed. This method has been associated with increased stress and pain in animals; therefore, it should be restricted to specific cases and combined with rectal massage and the administration of sedatives. Finally, spermatozoa can be recovered post-mortem from the cauda epididymis where they are already capable of fertilizing oocytes. After sperm collection, the evaluation of sample quality is essential to ensure success following the application of ARTs. Alongside the techniques commonly used in animal reproduction laboratories, more advanced and objective methodologies have been developed using technologies such as computer-assisted semen analysis (CASA) or flow cytometry. CASA systems enable the quantitative assessment of sperm motility at the individual cell level and the identification of sperm subpopulations associated with fertility. In parallel, flow cytometry expands analytical capabilities by allowing the simultaneous evaluation of multiple parameters indicative of sperm function in a single cell. This review summarizes the main methods of sperm collection across domestic mammal species, describing the respective advantages and disadvantages. Additionally, it provides an overview of the current methodologies for semen quality assessment and highlights the need for further advances in the identification of reliable fertility biomarkers.