The most important thing is not to stop the sperm metabolic activity during freezing process until the ice decoding so that the sperm motility and fertilization process delayed. This study was conducted to investigate the supplementary role of vitamin E (VE) in the use of amino acids on sperm freezability. Semen samples were collected from mature goats twice a week using an electro ejaculator. After initial evaluation and pooling process, samples were diluted with extenders containing 1 mM/ ml VE, 1 mM/ml VE +10 mM/ml L-glutamine, 1 mM/ml VE +10 mM/ml glycine, 1 mM/ml VE +10 mM/ml taurine, 1 mM/ml VE +10 mM/ml proline, 10 mM/ml L - glutamine, 10 mM/ml glycine, 10 mM/ml taurine and 10 mM/ml proline and control with no antioxidant. After 7–10 days, the frozen straws were thawed and assessed for different characteristics. The assessed CASA-results indicate that the diluents supplemented with glycine + VE, proline + VE and taurine + VE demonstrate significantly higher total motility and progressive motility compared to treatments. The data obtained for reacted acrosome present significantly no difference among control and treatments. Viability and membrane integrity were significantly improved using proline + VE, taurine + VE and glycine + VE, however, the acrosome status presents significantly no differences. MDA concentration of L. glutamine + VE and glycine + VE were significantly the lowest. The HS/WNS ratio was in control, VE and L. glutamine group significantly lower than other treatments, and the highest total antioxidant capacity and SOD were recorded in diluents using L. glutamine + VE, taurine + VE and glycine + VE. Moreover, the highest percentage of caspase activity for extenders containing L. glutamine, proline, taurine, glycine, VE and control, and the highest rate of viable spermatozoa was obtained for diluents supplemented with L. glutamine + VE, proline + VE, taurine + VE, glycine + VE. In conclusion, the synergism effect of 1 mM/ml VE +10 mM/ml amino acids in conventional freezing medium enhanced the effects of amino acids and improves the sperm qualities and confirmed the previous reports suggested using of amino acids as antioxidant in diluents which can protect the sperm from detrimental effects caused during cryopreservation process.
