Effects Of Cryopreservation On Sperm Morphology And Fertilization Ability In Cattle,Sheep And Goat

The cryopreservation technology of cattle sperm has been widely used,but the motility and fertilization rate of thawed sperm of sheep and goat are significantly lower than that of cattle sperm.In order to explore the sperm motility and fertilization rate of sheep and goat after thawing sperm for providing theoretical basis to improve the sperm motility and fertilization rate of sheep and goat after thawing sperm,three areas were studied in this experiment: 1.The acrosome integrity and ultrastructure of sperm head before and after cryopreservation were detected and compared between cattle,sheep and goat sperm;2.Sperm motility,hyaluronidase activity and acrosome enzyme activity of cattle,sheep and goat sperm before and after cryopreservation.were measured and compared;3.The in vitro fertilization ability of cattle,sheep and goat sperm was compared and analyzed.The results of this study are as follows: the results of the first part show that,(1)The acrosome of sperm stained by Jimsa is classified into five types:(1)intact acrosome?(2)acrosome membrane slightly expanding?(3)acrosome destruction?(4)acrosome partial shedding ?(5)acrosome all shedding.The sperm acrosome integrity rate among cattle,sheep and goats after cryopreservation decreased significantly(P <0.05).(2)The ultrastructure of sperm head were compared before and after cryopreservation and classified into four types:(1)intact plasma membrane and acrosome ?(2)expanding plasma membrane with intact acrosome ?(3)expanding acrosome?(4)vesiculatied-plasma membrane and acrosome.The percentage of the first three types of frozen sperm was was cattle>goat>sheep,and the acrosome integrity rate and ultrastructure of sperm of cattle,sheep and goat after cryopreservation showed the difference of breeds.The results of the second part showed that:(1)the sperm motility of cattle,sheep and goats after cryopreservation decreased significantly;cryopreservation caused the sperm motility of the three breeds decreased,which cattle>sheep>goats with significant differences between each groups.(2)Hyaluronidase activity and acrosome enzyme activity of cattle,sheep and goat sperm decreased significantly after cryopreservation.The activities of hyaluronidase and acrosome enzyme for frozen sperm were compared and showd cattle>sheep>goats with significant differences.The results of the third part show that:(1)the in vitro fertilized eggs cleavage rate for sperm before and after cryopreservation were cattle > sheep > goat,although there is no significant difference among each groups.(2)The cleavage rate of fertilized eggs decreased after cryopreservation in all three varieties,and there were significant differences between fresh sperm and frozen sperm in each groups.The results showed that cryopreservation could damage the acrosome and cell membrane of cattle,sheep and goat sperm,and there were significant species differences in cryopreservation tolerance.On the other hand,cryopreservation alsoresults in partial loss of fertilization-related motility,activities of hyaluronidase and acrosome enzyme in cattle,sheep and goats,which leads to the decline of fertilization ability.Based on the above results,it is speculated that sperm after cryopreservation affects the changes of structure and function related to fertilization in cattle,sheep and goats,but the theory or mechanism of differences among each species need further study from the reproductive biology and biochemical perspective.