Comparative characteristics of protocols for cryopreservation of ram semen

Purpose: study and comparison of protocols for cryopreservation of sperm of stud rams.Every day the popularity of sheep farming in Russia is increasing, since sheep are unpretentious in maintenance and at the same time they are multiproduct animals, providing the population with the necessary raw materials (wool, felt) and food products (meat, milk). For this reason, artificial insemination is of fundamental importance in the development of this branch of livestock farming, an important part of which is the correct cryopreservation of ram sperm. There are quite a few advantages of using cryopreserved sperm. Cryopreservation of sheep sperm contributes to the spread of the use of artificial insemination in this branch of the livestock industry. Freezing technology largely ensures the preservation of genetic material and its transportation, eliminating geographical barriers in the use of artificial insemination, and allows increasing the load on the ram sire without risk to his reproductive health. However, during the process of cryopreservation, sheep sperm receives irreversible damage due to cold shock, osmotic stress and oxidative processes, which lead to a decrease in the ability to fertilize sperm. Thus, chromatin may be damaged, membrane permeability increased, hyperoxidation and the formation of reactive oxygen species are possible, which affects the ability to fertilize. As a result, frozen ram semen may have low fertility. For this reason, it is extremely important to select an up-to-date freezing and thawing protocol with maximum recovery of viable and functional sperm of a given animal species for successful further use in artificial insemination. Technological advances in various fields of biotechnology have led to improvements in protocols, methods and equipment used in the laboratory, which have a positive impact on the reliability, accuracy of the procedure. This article summarizes research on the effects of different cryopreservation procedures, cooling rates, cooling times and thawing protocols on ram semen quality. In addition, a correct protocol for cryopreservation of Romanov breed sperm was formed, based on the results of our own research.