Results of testing the protocol for cryopreservation of bull sperm using a concentrated dilutent medium

Abstract

In recent years, dairy farming has been actively developing in Russia in many directions, providing consumers with milk, dairy products, meat and other raw materials. Particularly relevant are the automation of the processes of raising cattle and the selection of the most economically profitable dairy and meat breeds, which is facilitated by the development of artificial insemination in this agricultural sector. The success of artificial insemination is determined by many factors, including the quality of sperm extenders used and the correctness of cryopreservation protocols. The purpose of this study is to test a protocol for cryopreservation of Holstein bull sperm. The ejaculate was collected, evaluated, and pre-prepared (centrifugation, dilution, cooling). The freezing process was carried out using the method presented in the article by AnsariM.S., RakhaB. A. et al. (2015) for buffalo sperm: the straws were kept above liquid nitrogen vapor at a distance of 5 cm for 10 minutes, and then immersed in a Dewar flask. Sperm motility was assessed 3 times: after sperm collection, after cooling, and 0 hours after thawing. The negative impact of the cryopreservation process on the morphofunctional characteristics of sperm was determined. The study noted a decrease in the motility of progressively moving sperm by 21.53%, as well as a sharp increase in immobile sperm before and after cryopreservation from 6.8% to 33.82%. The number of nonprogressive spermatozoa was reduced from 9.12% to 2.91%. Changes in the morphological parameters of sperm as a result of cryopreservation (after cooling and 0 hours after thawing): the number of normal sperm decreased by 12%, the number of sperm with tail defects increased by 11% and head by 2%. Based on the data obtained, we can conclude that the use of this cryopreservation protocol, with preliminary preparation, helps preserve sperm viability. Further research will be aimed at studying and creating cryoprotectors that increase the safety of sperm of breeding bulls during deep freezing.