The production of reactive oxygen species during the process of cryopreservation, decrease the motility and cellular viability by initiation of lipid per oxidation of bio-membranes. For reduce these damages, antioxidants are used as cryoprotectants against the lipid per oxidation. The aim of this study was to assess the influence of vitamin E adding to the dilution media on standard qualitative parameters (motility, progressive motility, viability, hypo-osmotic swelling test, Acrosomal damages and normal spermatozoa) of pre and post frozen-thawed ram semen. Semen samples were collected by Electro ejaculator from 6 Zel rams, and diluted with a Tris-base extender containing vitamin E (1, 2 and 3 m/M) and without antioxidants (control). Diluted semen was cooled to 5oC and frozen in 0.25 ml straw, prior to being stored in liquid nitrogen. The results show that vitamin E has positive protection effects on the semen characteristics in chilled and frozen thawed. Motility, progressive motility, viability, hypo-osmotic swelling test and total normality of spermatozoa were higher in all groups of vitamin E supplement compare with control group, but highest percentages of treats were observed in 2m/M of vitamin E. Also the effect of vitamin E on Acrosome damages were significant in post frozen conditions and the highest percentages were obtained in control group. Therefore we recommend using 2m/M of vitamin E in Tris extender for short and long storages of Zel ram spermatozoa.

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