| The freezing-thawing process of bull semen significantly reduces the viability of sperm,seriously affects the cryopreservation effect of bull semen,and greatly limits the development of bull semen cryopreservation.Adding a suitable concentration of antioxidant substances to the bull semen diluent can effectively inhibit the oxidative damage of sperm,thereby improving the quality parameters and antioxidant properties of bull sperm after freezing and thawing.In this experiment,we first screened Qinchuan beef bulls and determined the best frequency and season of semen collection by analyzing the factors that affect the quality of fresh semen of Qinchuan beef bull;Then,different concentrations of grape seed proanthocyanidins(GSPs)and lycopene(LYC)were added to the frozen diluent of bovine semen,clarified the effect of these two antioxidants on the cryopreservation by detecting the quality and antioxidant properties of Qinchuan beef bull sperm after freezing and thawing.Finally,GSPs and LYC were added to the diet of Qinchuan beef bull respectively to test the semen quality and blood antioxidant properties of bulls before and after feeding these two antioxidants and confirm GSPs and LYC could improve semen quality by enhancing the antioxidant capacity of Qinchuan beef bulls.The following research results were obtained:1.The stability of the semen quality of different Qinchuan beef bulls is different.The suitable interval for semen collection of Qinchuan beef bulls is 2 to 4 days.Semen collection can be done in spring,autumn and winter.2.Adding GSPs during cryopreservation of Qinchuan beef bull semen can significantly improve sperm motility,acrosome integrity,membrane integrity,mitochondrial activity and the enzyme activities of CAT,GSH-Px after freezing-thawing,and significantly reduce the content of MDA in sperm.The optimal concentration of GSPs was 40 μg/mL(P < 0.05);after supplemental feeding of 20 mg/kg BW GSPs,the sperm motility of Qinchuan beef bulls was significantly improved,the sperm abnormality rate was significantly reduced,the enzyme activities of SOD,CAT and GSH-Px were significantly increased,and the content of MDA was significantly decreased in serum(P < 0.05).3.Adding LYC during cryopreservation of Qinchuan beef bull semen can significantly improve the sperm motility,physiological structural integrity(acrosome,membrane and mitochondria)and CAT,GSH-Px enzyme activities after freezing and thawing,and significantly reduce the content of MDA in sperm,the optimal concentration of LYC was 2μmol/L(P < 0.05).After supplemental feeding with 15 mg/kg BW LYC,the sperm motility of Qinchuan beef bulls was significantly improved,and the rate of sperm deformity was significantly decreased,the enzyme activities of antioxidant enzymes(SOD、CAT and GSH-Px)were significantly increased,and the content of MDA was significantly decreased in serum(P < 0.05).In conclusion,certain concentrations of GSPs and LYC can significantly improve the quality of fresh semen and frozen-thawed sperm of Qinchuan beef bulls,indicating that GSPs and lycopene can improve the antioxidant capacity of Qinchuan beef bulls to improve semen quality. |
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