Effects of pre-freeze Nigella sativa oil supplementation on cryosurvival of ovine spermatozoa.

The study was designed with three experiments to evaluate the effects of pre-freeze supplementation of Nigella sativa oil (NSO) and thymoquinone (TQ) on total motility, progressive motility, biokinetic characteristics, acrosomal integrity and DNA integrity of cryopreserved ovine spermatozoa. Semen samples collected from three proven fertile Merino rams were diluted with a Tris-based cryomedia containing different levels of NSO (Experiment I: 0, 10, 100 and 1,000 g/ml), TQ (Experiment II: 0, 1, 10 and 20 g/ml) and their optimum levels (Experiment III: 100 g/ml of NSO, 10 g/ml of TQ and 1 mM of α-tocopherol and cryopreserved as pellet (200µL) and subsequently evaluated at different post-thaw incubation periods (0, 2 and 4 hr). The results revealed that the percentage of total motility, progressive motility and biokinetic characteristics such as average path velocity, curvilinear velocity and straight-line velocity were higher (p < 0.05) in the sperm aliquots cryopreserved with 100 g/ml NSO or 10 g/ml TQ than in the sperm aliquots cryopreserved without supplementation just after thawing and 2 hr of post-thaw incubation. Among the supplements, NSO (100 g/ml) showed higher values of the total motility, progressive motility, biokinetic characteristics specially, average path velocity, curvilinear velocity and straight-line velocity, acrosome integrity and DNA integrity compared with the spermatozoa frozen without supplementation. Therefore, the results suggest that NSO may be added to the cryomedium to improve the cryosurvival of ovine spermatozoa.