Investigation of Different Glycerol and Egg Yolk Concentration on Freezing Bakhtiari Ram Semen

Purpose: Glycerol has been the most widely used cryopreservation agent for spermatozoa and a wide range of factors affects its action on sperm viability and fertilizing capacity. Moreover egg yolk is a common constituent of semen diluents, protects the spermatozoa against cold shock and confers protection during freezing and thawing .The aim of this study was to investigate of different glycerol and egg yolk concentration for optimum freezing of ram semen. Materials and Methods: Nine semen extender with different concentration of egg yolk (10%, 15%, 20%) and glycerol (4%, 6%, 8%) in a Tris-based media were tested for cryopreservation of semen. Semen was collected from Bakhtiari rams by an artificial vagina (38-40°C) two consecutive semen collections from each ram were pooled. The ejaculates were diluted with each extender, cooled to 5°C and left for 2 hours. Thereafter, it was packed in 0.5 ml straws (final cellular concentration 100-200 ×106 spz/ml). Then the frozen straws in nitrogen vapors (5 cm above nitrogen liquid). the straws were then stored in liquid nitrogen until further use. Results: The results showed that frozen sperm in all treatment groups had motility after thawing but the percentage of motility in different groups are different. Conclusion: In conclusion the results of present study indicate that the 20% egg yolk – Tris – 8% glycerol extender was significantly superior to other extender, in protecting the sperm during freezing and thawing and saving the motility of spermatozoa. While the 10% egg yolk – Tris – 4% glycerol show the lowest motility after freezing thawing.