Comparative analysis of protocols for cryopreservation of semen of breeding bulls

Sperm of breeding bulls with outstanding genetic characteristics is a valuable resource used mainly for artificial insemination of cows and improvement of offspring. The effectiveness of this technology is determined by the efficiency of sperm cryopreservation. The aim of this work is to analyze the effectiveness of various protocols for cryopreservation of bull sperm. It has been established that for fruitful insemination of cows, the presence of about 6 x 106 motile spermatozoa in a sperm dose (straw) after thawing is necessary. To obtain this result, it is necessary to carry out preliminary sample preparation, which includes centrifugation with subsequent removal of seminal plasma, dilution, cooling, and compliance with the deep freezing protocol (-196 ° C). Sugars, cholesterol-cyclodextrin, antioxidants included in the diluents have a positive effect on the effectiveness of cryopreservation protocols. One of the common technologies is the technology using an automatic mode, which includes cooling samples at a temperature of +4°C to -10°C at -3°C/min and from -10°C to -80°C at -40°C/min. Then, at a temperature of -80°C, the straws with sperm are immersed in liquid nitrogen. The optimal thawing technology is 35°C for 30 seconds.