Effect of seasons on cryopreserved sperm quality and subsequent fertility in Ouled Djellal rams.

This study aimed to investigate the effect of seasons on sperm cryopreservation and fertility outcomes in Ouled Djellal rams. For this purpose, sperm samples were collected from five fertile rams during winter, spring, summer and autumn and cryopreserved in liquid nitrogen. Sperm freezability was immediately assessed after thawing by evaluating CASA sperm motility parameters, membrane functionality, viability, acrosome integrity and lipid peroxidation. CASA sperm motility parameters were further assessed at 1, 2, 3 and 4 h after thawing. Fertility was evaluated for sperm cryopreserved in spring and autumn through cervical artificial insemination. Immediately after thawing, sperm cryopreserved in autumn, spring and summer exhibited significantly (p < 0.05) higher total and progressive motility, viability and membrane functionality than winter-frozen sperm. Among all seasons, summer-frozen sperm showed significantly (p < 0.05) lower velocities (VCL, VSL and VAP) and significantly higher (p < 0.05) lipid peroxidation. By 4 h after thawing, summer-frozen sperm maintained the lowest (p < 0.05) VCL, VSL and VAP values, whereas autumn-frozen sperm showed the highest (p < 0.05) values. Following cervical insemination, cryopreserved sperm yielded mean pregnancy and fertility rates of 66.66% and 58.33%, respectively, with spring-frozen sperm showing a higher fertility rate than autumn-frozen sperm (66.66 vs 50%). In conclusion, Ouled Djellal ram sperm demonstrated high freezability across all seasons, with spring and autumn being the most suitable. Sperm collected during these seasons supported satisfactory fertility after cervical insemination, providing valuable insights for the implementation of artificial insemination programs in sheep.