A comparative study on the effects of different cryoprotectants on the quality of canine sperm during vitrification process

Cryopreservation has the capacity to extend spermatozoa's lifespan and viability. In addition, the semen samples can be collected, preserved and stored or sent to distant locations and still be used long after the death of the semen donor. In this study for the vitrification of dog sperm (fresh and swum-up sperm), different cryopreservation mediums on the basis of glycerol, milk and egg yolk were used. Then, all of the samples were vitrified in the liquid nitrogen and thawed at least 48 hr later for re-examination of sperm parameters. The sperm parameters before and after cryopreservation in all groups were compared. It was found that during vitrification process, spermatozoa were damaged by the mechanical blows in centrifugation during swim-up processing, so they had less resistance than fresh semen. The examination of different cryoprotectants revealed that milk has better effects on the cryopreservation of semen than glycerol and egg yolk. With the comparison of the effects of glycerol and egg yolk as cryoprotectants, it was found that glycerol had better effects than egg yolk on the cryopreservation of the semen. In conclusion, milk might be used as a cryoprotectant instead of glycerol for canine sperm cryopreservation.