ADVANCED STUDIES ON IMPROVING SHEEP FERTILITY BY USING ARTIFICIAL MEANS OF REPRODUCTION

Artificial insemination (AI) in livestock is used to optimize reproduction efficiency. Compared to other semen preservation methods, cryopreservation is an established industry used worldwide for performing AI. Adequate protocols for semen collection and freezing and then for the use in the AI are set up for all the animal species. In sheep, AI with frozen-thawed semen resulted low fertility rate, which limits the practical application of this technique. Progressive sperm motility, sperm viability, sperm plasma membrane integrity and NAR were significantly (P < 0.05) higher for BIOX, MILK, and TEY extenders. Progressive motility increased significantly (p < 0.01) using licorice extract 10, 50 and 100 g/ml. Diluter type had a significant effect (p < 0.01) on sperm motility. The percentage of progressive motility in all extenders media containing LDL was also higher compared with 20% EY (control) during dilution and equilibration stages. All extenders containing LDL reduced the percentages of abnormalities after dilution as compared to control 20% egg yolk. The percentages of intact Acrosome in all other extenders containing LDL were significantly higher than 20% egg yolk extender. The highest percentage of postthaw progressive motility was recorded in extender containing 20mm glutamine. After dilution and equilibration, supplementation of glutamine at concentration of 40 and 60mm caused a significant increase in plasma membrane intact compared with control and all other concentrations tested. No significant difference between the control and the irradiated samples for viability However, the semen samples irradiated with 6.12 J/cm2 showed a slight increase in sperm progressive motility, viability, osmotic resistance, Acrosome and DNA integrity, respect to the semen samples irradiated at low energy doses and control semen samples. Cysteine effected on the ultra-structure of the ram sperm cell within the freezing- thawing dynamics. The positive effect of Cysteine could be a result of its interraction with membranes phospholipids during the freezing, giving it a better Cryopreservation.