Effect of Cholesterol and 7-Dehydrocholesterol on Bull Semen Freezing with Different Rates of Glycerol

The aim of this study was to evaluate the effect of 7-dehydrocholesterol loaded cyclodextrin (7-DHCLC) and cholesterol loaded cyclodextrin (CLC) with the addition of different glycerol (G) rates on bull semen cryopreservation. Semen samples of three bulls were pooled and divided into seven groups; control group (C) and the other six were extended with standard Tris extender including different G rates (3, 6 and 9%) with CLC or 7-DHCLC to reach 1.5 mg/120x10(6). Extended samples were frozen in 0.25 mL straws. After thawing, motion characteristics and motility, viability, acrosome integrity, mitochondria! activation, functional membrane integrity and abnormal spermatozoa rates were assessed.The highest membrane integrity, viability and total motility were detected in 7-DHCLC with 9% of G group (P<0.001). The lowest progressive motility was detected in 3% G groups (P<0.001). 7-DHCLC with 9% G had higher mitochondria! activity compared with 3% G groups. In addition, no statistical difference was observed between groups in terms of acrosome integrity and abnormal spermatozoa rates (P>0.05). According to these results, 7-DHCLC with 9% G addition maintained some spermatological parameters better than other groups after thawing in bull semen thus, it was concluded that 7-DHCLC could be used instead of CLC in bull semen cryopreservation.