Effect of Different Dilution Media on the Quality of Sheep Semen during LowTemperature Preservation at 4 ℃

Abstract:

This study aimed to evaluate the effects of different dilution media(containing egg yolk,soy lecithin,glycerol,etc.)on semen parameters of breeding rams after 6day storage at 4 ℃.The objective was to provide scientific evidence for the lowtemperature delayed preservation of fresh semen from breeding rams and improve the utilization rate of highquality breeding rams.Semen samples were mixed to eliminate individual differences,and the mixed semen was evenly divided into three portions and diluted with three different dilution media(Tris base solution+soy lecithin, Tris base solution+egg yolk,milk+fructose)at an isothermal condition to achieve a final sperm concentration of 40×10⁶/mL.Subsequently,the diluted semen was dispensed into 0.25 mL straws,sealed with polyvinyl alcohol,and stored in a constanttemperature refrigerator at 4 ℃.At 0,72,120 and 144 h after storage,sperm motility parameters were determined using a computer-assisted sperm analysis system(CASA),and sperm acrosome integrity and abnormality rates were assessed using eosin staining.The results showed that sperm motility was similar in all groups at the initial state,and no abnormalities were detected.However,with the extension of storage time,sperm motility gradually decreased,and the abnormality rate gradually increased.Particularly after 144 h of storage,the milk+fructose group exhibited the lowest sperm motility and the highest abnormality rate.In contrast,the Tris base solution+soy lecithin group showed better maintenance of sperm motility in the short term,with a relatively low sperm abnormality rate.Therefore,this study indicates that selecting the appropriate dilution media is crucial for maintaining sperm motility and reducing the abnormality rate during lowtemperature preservation of semen from breeding rams at 4 ℃.Among them,the Tris base solution+soy lecithin dilution media demonstrated good application potential.