Effect of cholesterol-loaded cyclodextrins on cryosurvival of dog spermatozoa
Cryopreservation affects integrity of cholesterol and phospholipids in the plasma membrane of sperm leading to decreased fertility of frozen-thawed semen. Cholesterol-loaded cyclodextrins (CLC) have been shown to improve post-thaw semen quality in various species. The aim of this study was to investigate the optimal concentration of CLC for better post-thaw semen quality in dogs. Semen collection, through digital manipulation, was conducted once a week in four adult German shepherd dogs (n = 20 ejaculates; five ejaculates/dog). Semen samples with mass motility>3 (0: without movement; 5: fast progressive movement), motility >70% and concentration >200 × 106/ml were pooled and processed in Tris-citrate extender containing 0, 1, 2 or 3 mg of CLC. The post-thaw quality was assessed on the basis of percentage motility, morphological abnormalities, live/dead ratio and plasma membrane, acrosome and DNA integrity, evaluated using anova and further analysed by Tukey's range test, if applicable. The addition of CLC showed an overall improvement in post-thaw semen quality. Among various treatment groups, and when compared to the control, the percentages of motile (55.5%), viable (65%), plasma membrane intact (56.7%), acrosome intact (49.2%) and DNA intact (98%) spermatozoa were significantly higher in 2 mg/ml CLC group (p < .05). It is concluded that incorporation of cholesterol in semen extender results in a beneficial increase in post-thaw semen quality in dogs.