Effect of Different Thawing Methods on Post-thaw Motility of Cow Semen in Cryopreservation Straws

The study was to investigate the effects of different thawing temperatures(5,15,40,75,90 ℃) and times(1- 120 s) on properties of post-thaw cow semen by detecting frozen-thawed semen motility,acrosome integrity and tail membrane integrity,further obtaining the optimal thawing method of straw frozen semen from dairy cow. The results showed that(1) Thawing of the straw frozen semen of dairy cow at 75 ℃ for 3 s yielded the highest semen motility,followed by 40 ℃for 20 s,and the least by low temperature 5 ℃ and room temperature 15 ℃ with a semen motility of 0. 3,moreover thawing at high temperature 90 ℃ was not suitable for large scale production due to the difficult control of the temperature;(2) The acrosome intact rate and plasma membrane integrity rate of semens thawed at90 ℃ were remarkably lower than that at 40 ℃ and 75 ℃ significantly(P 75 ℃ > 90 ℃. In practice,the thawing method of straw frozen semen of dairy cow should be selected according to the specific circumstance and inseminated immediately,with the recommended condition of thawing at 75 ℃ for 3 s. If the thawed semen could not be inseminated immediately,the thawing should be performed at 20 s for 40 ℃to maintain the motility for a longer term.