Improvement of cryopreserved rooster semen quality by combined application of DMF and ZnO NPs

Semen cryopreservation represents a pivotal technology for the long-term conservation and efficient utilization of poultry genetic resources. The primary challenge impeding the implementation of this technology pertains to the phenomenon of frozen-thaw-induced oxidative stress damage to spermatozoa. Zinc oxide nanoparticles (ZnO NPs) have been demonstrated to exhibit remarkable antioxidant capacity within the context of biomedical applications. The present study therefore systematically evaluated the effects of adding ZnO NPs to a dimethylformamide (DMF) cryoprotectant on the morphology, antioxidant capacity, and reproductive potential of frozen-thawed sperm. The results demonstrated that, in comparison with the DMF group, the ZnO-DMF group exhibited significantly increased plasma membrane integrity, mitochondrial activity (MA), total antioxidant capacity (TAC), and glutathione peroxidase (GPX) and glutathione reductase (GR) activity in frozen-thawed sperm (P < 0.05). Concurrently, the rates of abnormal morphology, DNA fragmentation index (DFI), and malondialdehyde (MDA) content were significantly reduced (P < 0.05). Following artificial insemination, the fertilization rate of the experimental group 87.92% ± 10.66, the hatching rate was 97.79% ± 3.59, and late embryonic mortality was found to be significantly lower than in the control group (P < 0.05). In summary, the study demonstrates that ZnO NPs enhance sperm antioxidant capacity and exhibit synergistic protective effects with DMF, effectively mitigating cryopreservation-induced damage. This finding provides scientific rationale and technical support for the optimisation of rooster semen cryopreservation protocols and the enhancement of the efficiency of poultry genetic resource conservation.