Effect Of Freeze-thaw Temperature And Melatonin Effect On Cryopreservation Of Chicken Semen

Semen cryopreservation can effectively protect germplasm resources and also improve the utilization rate of improved poultry.At present,the research on chicken semen freezing technology is not fully common.Due to factors such as freezing,thawing temperature,equilibration time,diluent and antifreeze concentration,the sperm motility is reduced after freezing and thawing thereby causing oxidative damage.Melatonin is a substance that can be synthesized and secreted by the pineal gland in the body and has a good antioxidant effect.In the past,its role in semen freezing has focused on mammals such as humans and mice,but its role in avian frozen semen has rarely been studied.This study focused on the freezing and thawing temperature of chicken semen and the effect of melatonin on the freezing effect of frozen semen in cock.The sperm motility,plasma membrane integrity rate and acrosome integrity rate after freezing and thawing were determined by optical microscopy,sperm tail hypotonic swelling and Jiemsa staining technique.ELISA Kit was used to detect the contents of superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GPx),malondialdehyde(MDA)and reactive oxygen species(ROS)after semen thawing.The research results were as follows:1.The chicken semen pellets were frozen at 1,2,3,4,5,and 6 cm from the surface of the liquid nitrogen,and the pellets were thawed in a 36,37,38,39,40,and 41?water bath,and the sperm was examined by microscopic observation.The results showed that the chicken semen pellets frozen at a distance of 3 cm from the surface of the liquid nitrogen,and the thawing activity was also highest at 38?.2.Different MEL concentration of 0,0.125,0.25,0.5 mg/ml was added to the frozen dilution of the chicken semen,and frozen-thawed,and then the sperm motility was observed by microscopic observation,sperm tail by hypotonic swelling method and acrosome integrity by the jiemsa staining method.The ELISA set kit was used to determine the levels of SOD,CAT,GPx,MDA and ROS in the semen after thawing.The results showed that the addition of 0.25 mg/ml melatonin significantly increased the sperm motility,plasma membrane integrity and acrosome integrity rate after thawing(P<0.05),and significantly increased the SOD,CAT and GPx levels of semen after thawing(P<0.05).In contrast,0.25mg/mL MEL significantly reduced the levels of MDA and ROS in the semen after thawing(P <0.05).The results of this study also showed that chicken semen frozen at 3 cm from the surface of liquid nitrogen and thawed in a 38?water bath had the highest sperm motility.In conclusion,adding an optimum 0.25 mg/ml MEL significantly improved the sperm motility,plasma membrane integrity,acrosome integrity and the antioxidant enzymes(SOD,CAT and GPx)after freezing and thawing while efficiently decreasing the MDA and ROS levels after thawing.