Effects Of Melatonin On Boar Sperm Quality During Liquid Preservation

Artificial insemination has been widely used in pig production.In the process of artificial insemination,dilution and preservation of boar semen is the key step to improve the quality of semen preservation,and the semen from liquid preservation has been widely used in pig artificial insemination.However,the sperm quality is determined by the various physical and chemical factors during liquid preservation.In boar sperm,the energy substrates are consumed and reactive oxygen species(ROS)are accumulated gradually with the extension of preservation time.Although the appropriate amount of ROS act as an important physiological molecule for promoting sperm's function,excessive ROS will damage the sperm structure and function that lead to the decrease of sperm quality.Therefore,supplementation of antioxidants to boar semen extender has been become an important method to improve sperm quality via reducing the oxidative stress.In this study,different concentrations of melatonin were supplemented to Modena extender during the liquid preservation at 17?.To explore the effects of melatonin on boar sperm quality and find out the optimum concentration,sperm progressive motility,membrane integrity,acrosome integrity,cellular ATP content,mitochondrial membrane potentials,ROS level,lipid peroxidation(LPO)and total antioxidant capacity(T-AOC)were measured at different preservation days.The main results obtained in this study are as follows:1. Melatonin improved the boar sperm quality during liquid the preservation at 17?.Different concentrations of melatonin were added to the Modena extender.Among them,sperm added with 0.1?M melatonin showed higher sperm progressive motility,membrane integrity and acrosome integrity than the control(p<0.05).2. Melatonin acted as an antioxidant during liquid preservation at 17?.Compared to the control,sperm with 0.1?M melatonin treatment showed lower level of ROS,LPO and higher level of mitochondrial membrane potentials,ATP content as well as sperm T-AOC(p<0.05).The results indicated that melatonin protected boar sperm by its antioxidant capacity.Moreover,melatonin decreased the boar sperm apoptosis during liquid preservation.In our study,it was observed that addition of 0.1?M melatonin to Modena extender significantly decreased the levels of Cleaved Caspase-3 and Cytochrome C(p<0.05).3. Semen were incubated with menadione at 37? for 3 h as an oxidative stress model.Sperm progressive motility,membrane integrity,mitochondrial membrane potentials,ATP content,ROS level and T-AOC were detected.When compared to the menadione treatment,it was observed that 0.1?M melatonin significantly improved sperm progressive motility,membrane integrity,mitochondrial membrane potentials,ATP content,T-AOC,and decreased the ROS level(p<0.05).Those observations suggesting that that melatonin could protect sperm via its antioxidant effects.In summary,melatonin could improve the boar sperm quality preserved at 17? and the optimal concentration was 0.1?M;Moreover,melatonin could also decrease the apoptosis of boar sperm during the liquid preservation.Therefore,addition of melatonin to Modena extender might contribute to prolong the storage time and improve the boar sperm quality.