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Cryopreservation of boar semen causes oxidative damage to sperm. Semen needs to hold at 17°C for a period of time prior to cryopreservation. Holding time allows interaction between sperm and seminal plasma to improve sperm quality after thawing. The aim of this study was to investigate the effect of prolonging holding time of collected boar semen on sperm antioxidant capacity and frozen-thawed quality. Collected semen was held at 17°C for 3 hours and 24 hours respectively. A part of the semen was irradiated with ultraviolet (0.6 J/cm²), and the remaining semen was cryopreserved. The semen samples were evaluated sperm motility, viability, mitochondrial membrane potential (MMP) and acrosome integrity. Besids, the sperm malondialdehyde (MDA) level was measured after being irradiated with ultraviolet. The results showed that the sperm motility, viability, and MMP of ultraviolet irradiated or frozen-thawed semen held at 17°C for 24 hours were significantly higher (P < 0.05) than those of 3 hours holding time. The ultraviolet irradiated sperm MDA level of 24 hours holding time was significantly lower (P < 0.05) than that of 3 hours. In summary, boar semen holding at 17°C for 24 hours could effectively reduce ultraviolet irradiated sperm MDA level and the oxidative damage to sperm, and improve the sperm quality of frozen-thawed semen. [ABSTRACT FROM AUTHOR]

Sperm are vulnerable to oxidative damage during the preservation of boar semen. Light is one of the causes of the damage. Therefore, collected semen should be preserved in the dark to reduce the oxidative damage to sperm. The aim of this study was to evaluate the effect of ultraviolet (UV) irradiation on boar sperm oxidative damage and sperm quality. Boar semen was held at 17°C for 0 hour and 3 hours, respectively, and irradiated with different intensities of ultraviolet (0, 0.2, 0.4, 0.6, 0.8, 1.0 J/cm²). Sperm quality was determined by assessing the sperm motility, viability, mitochondrial membrane potential (MMP), acrosome integrity and reactive oxygen species (ROS) level. The results showed that only ROS level of UV irradiated sperm held at 17°C for 3 hours was significantly lower than that of 0 hour holding time. Increasing the intensity of UV irradiation significantly reduced the total motility, progress motility, mitochondrial membrane potential and viability of sperm, and increased the ROS level. The UV intensity of 0.6 J/cm² irradiation could reduce 50% sperm total motility, but it had no effect on the sperm acrosome integrity. In the conclusion, UV irradiation caused oxidative damage to sperm and reduced sperm quality. There's dose-effect relation within UV irradiation. However, boar semen held at 17°C for 3 hours could effectively reduce the oxidative damage to sperm. [ABSTRACT FROM AUTHOR]