Artificial insemination (AI) in rams relies on effective sperm preservation; however, freezing and thawing pro cesses induce oxidative stress and sperm damage. This study evaluated the antioxidant effects of curcumin, in both free and nanoparticles (NPs) forms, on cryopreserved ram sperm. Curcumin was incorporated into the sperm extender at concentrations of 0, 25, and 50 μ M. The curcumin NPs formulation, prepared using the nanoliposome technique, improved curcumin solubility and bioavailability. The 25 μ M curcumin NPs group showed significantly higher sperm motility (total motility: 72.67 ± 1.15 %, progressive motility: 59.2 ± 0.96 %) compared to the control (total motility: 59.75 ± 0.68 %, progressive motility: 46.23 ± 1.50 %) (p < 0.05). Membrane (75.77 ± 0.87 %) and acrosome integrity (80.67 ± 0.87 %) were significantly improved in the 25 M NPs group compared to those in the control (61.76 ± 0.97 %, 66.77 ± 1.50 %) (p < 0.05). Sperm viability was higher in the 25 μ μ M NPs group (76.76 ± 1.22 %) vs. control (64.93 ± 0.80 %) (p < 0.05), and early apoptosis was reduced (5.06 ± 0.36 % vs. 9.7 ± 0.7 %) (p < 0.05). Oxidative stress markers were also improved, with lower MDA and ROS levels and enhanced antioxidant enzyme activity. The 25 μ M curcumin NPs did not alter CYTb copy number. The 25 μ M curcumin NPs group had higher fertility outcomes, including pregnancy (58.33 %), birth (58.33 %), and lambing (83.33 %) rates, than the control and 50 μ M curcumin groups. These findings indicate that curcumin nanoparticles enhance sperm quality and fertility in cryopreserved ram sperm.
