The present study aimed to evaluate quality of pre and post frozen-thawed ram semen processed with extender containing different levels of vitamin C as antioxidant. Pooled semen's were collected from 6 rams and diluted with Tris – egg yolk (TEY) extender. The diluted semen was divided to 4 aliquots including control (o) and 1, 2 and 3 mg/ml vitamin C and was cooled at 5°C and their qualities were evaluated during pre-freezing and then the cooled semen samples were packaged into 0.25 ml straws. Straws were frozen in the vapor of liquid nitrogen and thawed ten days Routine semen evaluations like sperm motility, progressive motility, viability, hypo-osmotic swelling test (HOST), normal spermatozoa and acrosome defects in pre and post freezing process were conducted. Results showed that the effects of vitamin C in Tris extender on some characteristics of spermatozoa were significant compare with control group, but different levels of vitamin C were not significant. The highest sperm motility, viability, normal spermatozoa and HOST were achieved by addition of 2mg/ml of vitamin C in Tris extender. On the basis of the present results it is concluded that supplementing TEY extender with vitamin C improved quality of Zel ram spermatozoa in chilling and freezing conditions.

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