Determination of the egg yolk optimum level in the goat sperm freezing extender by In vitro evaluations

This research aimed to evaluate two concentrations of egg yolk inclusion rate (15% and 20%) in the semen extender of goat semen cryopreserved during breeding season. Thirty ejaculates were collected from five trained Mahabadi goats and diluted in egg yolk based extenders. The semen samples were frozen, and after thawing evaluated for seminal characteristics i.e. sperm motility and morphology, membrane and acrosome integrity, viability, apoptosis status and DNA fragmentation. The data were analyzed using GLM procedure in SAS software. There were not significant differences in total and progressive motility of sperm in 20% egg yolk extender (69.00±1.69 and 52.57±1.29 respectively) and 15% egg yolk extender (68.21±1.69 and 52.35±1.29 respectively). Moreover, sperm viability, membrane integrity, and normal sperm cells percentage in extender with 20% and 15% egg yolk were evaluated to be (83.88±1.08, 72.80±2.43, and 84.31±1.85) and (86.65±1.08, 72.37±2.43, and 79.25±1.85) respectively. Also, in the terms of sperm with intact acrosome and DNA fragmentation rate, no significant differences were observed in the extenders. In the apoptosis test, more live sperms were observed in the group containing 20% egg yolk compared with the one containing 15% egg yolk. To elucidate the effect of diluents used in present study on sperm fertility, further studies should be conducted in vivo.