Effect of extender type on freezability of ram semen [electronic resource].

Includes references.

Semen was collected from 4 adult Ossimi rams (2-4 years) by artificial vagina. Ejaculates having 2:80% motility and sperm concentration of 2:3 x 1ft/ml were pooled together and gently mixed to study the effect of selected five extenders on freezability of ram spermatozoa by split -sample technique. Two extenders (A and B) were free of skim milk and three extenders (C, D and E) contained skim milk at various levels (35, 50 and 65%, respectively). The final glycerol level was 14.5% and the dilution rate was 1:6 (v/v). Semen was equilibrated for 3 h at 4-5 ·C. The frozen semen was thawed in water bath at 42 'C for 35 seconds. Sperm motility, livability and abnormality were evaluated just before and after glycerolation, after equilibration and post-thawing offrozen semen. Results indicated that extenders A and B have yielded significantly (P<0.01) the highest percentage of post-thawing motility (35.6 and 42.5%), livability (37.0 and 42.1%), and the least sperm abnormality (23.8 and 19.7%), as compared to 31.3, 23.1 and 21.3% for motility, 31.9, 25.4 and 23.3% for livability and 21.51, 24.99 and 26.74% for abnormality of extenders C,D and E, respectively. Post-thawing motility and viability progressively decreased as the skim milk content in the extender increased, while the post-thawing abnormality showed an opposite trend. The differences were significant (P<0.01). B-extender maintained superior post-thawing recovery rate of ram spermatozoa, being 58.6% for motility and 58.2% for livability relative to equilibrated values and 46.5 for motility and 46.1% for livability relative to initial values. Total abnormality increment was 17.68%. The least respective values for motility and viability and the higher value for abnormality were expressed by the E-extender, which contained the greatest skim milk. The loss in motility between equilibration and thaWing ranged from 28.8 to 36.9% and the least values (5.6-8.7%) were obtained between glycerolation and equilibration. The corresponding values were 28.5-33.4% and 5.5-9.5% for livability and 12.37-15.72 % and 1.68-2.78% for abnormality, respectively. In conclusion, tris-based extenders have higher freezability for ram semen as compared to skim milk extenders.

Summary in Arabic.

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