An increase in the viability of ram sperm when cultured in modified medium for in vitro fertilization

Modern livestock necessitates controlled breeding, one of the main methods of which is a long-term preservation of animal reproductive qualities at cell level. In recent years, a considerable progress has been achieved in the development of techniques of animal sperm preparation for in vitro fertilization (IVF). In these, the main purpose is to obtain population of motile sperm with a suitable morphology capable of in vivo or in vitro oocyte fertilization. However, these methods are not always effective because of the lack of standards for the procedure. We first in Russia carried out a study on the viability of ram sperm cultured in the modified IVF medium. The semen was sampled from North Caucasian rams, 2-3 years of age, according to a routine technique, used for sheep and goats' artificial insemination, and domestic State Standards GOST 32222-2013. Sperm was evaluated on organoleptic and microscopic parameters, and cultured for capacitation to render the spermatozoa competent to fertilize an oocyte according to the prototype procedure, described by A.P. Gandhi (2000), and the method, developed by us. In the modified procedure, the sperm is brought to glucose-yolk-citrate diluent (GYC) and then transferred to medium SOF wash, prepared without glucose and supplemented with glutamine with 6 mg/ml bovine serum albumin, 0.2 mg ml caffeine and 50 mg/ml heparin. The developed technique increased the activity of sperm by 1.3 points compared to the commonly used method, the number of live semen increased by 43.7 %, their vitality increased 1.6 times and the number of spermatozoa with rectilinear movements was 1.6 times higher. Thus, the developed technique significantly improves ram sperm qualitative and quantitative characteristics and allows us to recommend this method of animal sperm maturation for in vitro fertilization procedure.