Use of bull sperm extenders: current status (review)

In recent years, assisted reproductive technologies in animal production have included artificial insemination in need of high-quality cryopreserved bull sperm. High-quality freezing depends on the optimally selected parameters of the semen diluent. In this connection, the purpose of this review is to spread the knowledge about the use of various types of diluents and additives to them in the cryopreservation of bull semen to improve its quality. This article provides an overview of 64 scientific papers of domestic and foreign researchers on modeling diluents in order to ensure the maximum yield of high-quality sperm after thawing. Research into the creation of an optimal sperm diluent to ensure sperm protection and save high-quality sperm from cryoinjury during a long time, which can long preserve its properties in liquid nitrogen has been carried out since the mid-20th century. Classic media with a known composition (LPG, Tris, MOPS, etc.) and commercial media (Andromed, BullXcell, OptiXcell, etc.) are used to dilute bull sperm before cryopreservation. The use of different variants of bull sperm extenders by researchers from different countries provides important information on the effect of extender compositions on sperm quality parameters, such as motility, viability, percentage of abnormal sperm, etc., after long-term cryopreservation. Also, recently, the inclusion of additives of natural or synthetic origin in extenders, which exhibit different effects on sperm and spermatozoa, has been widely used. This review may be useful for organizations and laboratories engaged in the development of technologies for creating bull sperm extenders.