Effect of Supplementation in Semen Extenders on Post-Thaw Sperm Quality in Thai Native Bulls.

Cryopreservation is a widely used technique for long-term semen storage; however, it can induce oxidative stress, compromising sperm quality. This study examines the effect of (KP) supplementation in semen extenders on the post-thaw sperm quality of Thai native bulls. Fresh semen was collected and evaluated for motility, viability, and concentration prior to cryopreservation. Semen samples were allocated to four treatment groups: 0 mg/mL (control), 0.5 mg/mL, 1 mg/mL, and 1.5 mg/mL KP. Subsequently, the samples were frozen, then thawed, and analyzed for sperm motility, viability, membrane integrity, and oxidative stress. The results showed that supplementation with 1.0 mg/mL KP significantly improved sperm motility (46.29 ± 2.66%) and viability (43.42 ± 2.15%) compared to the control (40.77 ± 2.76% and 38.63 ± 2.66%, respectively). Membrane integrity was also enhanced (47.64 ± 1.18% vs. 41.85 ± 1.98% in the control), while oxidative stress levels were reduced (MDA concentration: 2.33 ± 0.29 µM/mL vs. 2.73 ± 0.33 µM/mL in the control). However, the highest concentration (1.5 mg/mL KP) negatively affected sperm quality, with reduced motility (36.97 ± 3.32%), viability (30.88 ± 3.02%), and membrane integrity (35.64 ± 1.61%). These findings suggest that 1 mg/mL KP is the optimal concentration for improving post-thaw semen quality in cryopreservation protocols for Thai native bulls.