Protective Role of Curcumin in Ram Sperm Cryopreservation: Evaluation of Spermatological Parameters and PRDX5 Gene Expression

Abstract

Cryopreservation of ram sperm is a cornerstone in reproductive biotechnology but is often accompanied by oxidative damage that compromises post-thaw sperm quality. Curcumin, a natural polyphenol with potent antioxidant properties, may offer protection against cryo-induced injuries. This study evaluated the effects of curcumin supplementation at two concentrations (10% and 20%) in semen extenders on the functional and molecular characteristics of ram spermatozoa. A total of 14 ejaculates were collected from healthy adult rams and randomly allocated into three groups: control (no curcumin), C1 (10% curcumin) and C2 (20% curcumin). Semen samples were cryopreserved using a Tris-based extender, and post-thaw evaluations included total motility, viability (eosin-nigrosin), morphology (head, midpiece, tail abnormalities), membrane integrity (HOST), chromatin integrity (toluidine blue) and PRDX5 gene expression via qPCR. Curcumin supplementation, particularly in the C2 group, significantly improved total motility and viability (p < 0.01), while reducing head and tail morphological abnormalities and chromatin damage (p < 0.05), compared to the control. No significant difference was observed in PRDX5 gene expression among groups (p > 0.05). These improvements are likely attributed to curcumin's antioxidant activity, including ROS scavenging and membrane stabilisation. Curcumin supplementation in semen extenders enhances post-thaw sperm quality in rams by improving functional parameters and maintaining chromatin integrity, without modulating PRDX5 gene expression. These findings support the potential of curcumin as a safe and effective cryoprotective additive in ovine artificial insemination and genetic conservation protocols. Further research combining transcriptomic and proteomic analyses (or approaches), along with validation of post-thaw sperm fertility, is needed to clarify curcumin's effects and its potential in livestock breeding.