IMPACT OF ZINC AND TOCOPHEROL ON FUNCTIONAL COMPETENCE OF CRYOPRESERVED BUFFALO PERMATOZOA

Five buffalo-bulls aged 3-4 years were used in the present work. They were classified into four groups. Group I involved one buffalo-bull, which served as a control. Group II included one buffalo - bull which was orally supplemented with 6.9 grams zinc oxide every week for three months. Group III involved one buffalo-bull, which was orally supplemented with Img dl-a-Tocopherol acetate/day/kg live body weight for three months. Group IV consisted of two buffalo-bulls which were orally supplemented with zinc oxide and dl-a-Tocopherol acetate. Semen was collected (before and after dietary supplementation) from each buffalo-bull in a regular service. Ejaculates were extended in tris-based extender without or with 0.25 mg dl-a-Tocopherol acetate, 1 mM zinc chloride and 1.5 mg/ ml dl-a-Tocopherol acetate + 1 mM zinc chloride as additives. Cooling and freezing of extended semen was done using MV system. Frozen-thawed straws were evaluated for percentage of sperm motility, Viability Index, acrosomal integrity percent and the distance that buffalo spermatozoa passes through the cow cervical mucus In addition, detection of the structural integrity of sperm plasma membrane was done by estimating the loss of the intracellular aspartate aminotransferase after freezing and thawing. The obtained results revealed that the percentage of individual motility after dilution did not significantly increase except after in vivo and in vitro supplementation of zinc, the post thawing motility was highly significant (p < 0.01) increase in all treatments over that was found in the control group except after in vitro addition of zinc or tocopherol the figures obtained were significantly (p < 0.05) higher from the control. Also, viability index was significantly increased in all
treatments except in vivo supplementation of zinc which did not evoke any significant effect if compared to that observed before treatments. The effect of zinc and/or tocopherol in tris based diluent before freezing of semen from dietary zinc and tocopherol supplemented buffalo bulls resulted in highly significant reduction of the percentage of defected acrosomes. The sperm penetration distance was proved a highly significant which focusing the importance of adding Tocopherol to semen diluents. Also, The present study confirmed the protective action of zinc and /or vit. E on the plasma cell membrane of buffalo spermatozoa after freezing and thawing as indicated from the minimum rate of extracellular enzyme (Aspartate aminotransferase and acid phosphatase) released. It was concluded that in vitro and /or vivo supplementation of Vit. E and /or zinc proved to protect the plasma membrane of buffalo spermatozoa during freezing and thawing.