The Effect of Metallic Nanoparticles Supplementation in Semen Extender on Post-thaw Quality and Fertilizing Ability of Egyptian Buffalo (Bubalus bubalis) Spermatozoa

Nanomaterials offer several promising prospects in the field of farm animal reproduction, encompassing a broad range of applications such as transgenesis and the precise delivery of substances to sperm cells, antimicrobial, antioxidants properties as well as their potent role in improving cryopreservation methods. The aim of the present study is to explore the effect of supplementing the semen extender with 10 µg/mL nano gold (Au-NPs10), 10 µg/mL nano silver (Ag-NPs10), 1 µg/mL nano selenium (Se-NPs1), and 100 µg/mL nano zinc oxide (ZnO-NPs100) on sperm characteristics and kinematics parameters, acrosome integrity, oxidative biomarkers, morphological and apoptosis-like changes of frozen-thawed buffalo bull sperm, and, ultimately, their fertilizing capacity. The results revealed that all aforementioned nano materials significantly improved viability, progressive motility, membrane integrity, acrosome integrity, and kinematic parameters as well as apoptosis-like changes of post-thawed buffalo bull sperm compared to the control (p < 0.05). No discernible effects were observed on sperm ultrastructure morphology measures as a response to the addition of these metallic nanoparticles to the extender. The values of caspase 3 significantly decreased by 64.22, 45.99, 75.59, and 49.39% in Au-NPs10, Ag-NPs10, Se-NPs1, and ZnO-NPs100 treated groups, respectively, compared to the control. The addition of 100 µg ZnO-NPs to the extender significantly decreased the total count of bacteria, fungi, and yeast compared to the control (p < 0.05). The AuNPs10 and SeNPs1 treated groups showed lower content of malondialdehyde, hydrogen peroxide, and nitric oxide concentrations and higher values of total antioxidant capacity of post-thawed extended semen (p < 0.05). Pregnancy rates increased by 17.5, 20, and 30% in buffalo cows inseminated with sperm treated with ZnO-NPs100, Se-NPs1, and Au-NPs10, respectively, compared to the control group. The present results indicate that the freezing extender supplemented with metallic nanoparticles can be an effective strategy to enhance the cryotolerance and fertility potential of buffalo bull sperm.