Study On Freezing-Preservation Technology On Boar Semen Frozen In 5ml Straws

In order to develop cryopreservation techniques of boar semen to be applied to commercial production, experiments were carried out to determine optimum package, freezing method, diluents and additives, glycerol concentration, sperm concentration, thawing temperature and time in freezing boar semen by evaluating post-thaw sperm quality. The ultrastructural changes of sperm before and after cryopreservation were evaluated under electron microscope. During freezing procedure different temperature were wrote down to make freezing temperature curve. The results were as follows:There was no significant difference among the post-thaw motility and viability of boar semen frozen in pellets, 0.25 ml mini-straws and 5 ml maxi-straws(P > 0.05). 0.25 ml mini-straws had significantly higher post-thaw tail coiling rate and normal acrosome rate (NAR) than pellets(P < 0.05), but had no significant difference with 5 ml maxi-straws. Three freezing temperature curve were set down respectively with different beginning frozen temperature, balance temperature and enter nitrogen temperature.Among the four diluents used, diluents 4(LEY) has significantly higher post-thaw sperm motility, tail coiling rate and NAR than the other three diluents(P < 0.05), and had extremly significant higher post-thaw sperm viability than the other three diluents(P < 0.01).Diluents with 2% and 3% glycerol concentration had the highest post-thaw sperm motility, viability and NAR among the five different glycerol concentrations. 1%~3% glycerol concentration was effective for protecting post-thaw sperm membrane.