Study On Cryopreservation Of Boar Semen

In order to obtain better boar frozen-thawed semen for artificial insemination, hand-holding method was used to collect boar semen. The effects of different pre-diluted extenders, different thawing protocols and extenders using 0.25 ml straws and 5 ml Maxi-straws were investigated. The glycerol equilibration time, pre-equilibrium temperature and different distances above liquid nitrogen (LN₂) surface were also studied. The results were summarized as follows:Experiment 1. Study on cryopreservation of boar semen using 0.25 ml straws.Using Zo, BTS, Schonow I as pre-diluted extenders and thawing extenders, we compared the effects of different pre-diluted extenders, different thawing protocols and extenders and the different distances from liquid nitrogen (LN) surface. We found that,using Zo, BTS, Schonowâ… as pre-diluted extenders, the result is better than using no pre-diluter extenders, the effects of Zo and the Schonowâ… are better than BTS.when using Zo, BTS, Schonowâ… as thawing and extenders, the effects of Zo and Schonowâ… were not significant. The effects of Zo and the Schonowâ… are better than BTS.5cm was the suit distances from liquid nitrogen (LN) surface for 0.25ml straws. And the suit pre- equilibrium temperature is 5℃.The suit thawing protocol is 37℃, 30s. We screened out a set of stable frozen-thawing protocol: the boar semen were pre-dilited with ZO,pre-equilibrated at 5℃for 1.5h, then add the extenderâ…¡,the concentration of Glycerol is 3%.and held for 2h in extenderâ…¡; cryopreservated below 5cm from liquid nitrogen (LN) surface then the samples were held at 37℃for 30 sec, reextended in 2ml ZO. The motility of samples maintained on 0.45.Experiment 2. Study on cryopreservation of boar semen using 5 mI Maxi-straws:Using 5ml Maxi-straws as the freezing package, we compared the effects of different concentrations of Glycerol, different thawing protocols and the different distances from liquid nitrogen (LN) surface. And we found, for 5ml Maxi-straws, cryopreservated below 5cm from liquid nitrogen (LN) surface is the suit protocol.. The suit thawing protocol is 37℃, 30s. And the concentrations of Glycerol, 2%and 3% shows no significant. But using the best protocols, the motility of samples is only 0.21.Much lower than using 0.25ml straws.Experiment 3. The IVF experiment using cryopreserved boar semen.The effect of IVF of cryopreservated boar semen compared to frozen-ejaculated spermatozoa were investigated. The results showed that the rate of cleavage and embryo developing to 16-cells in cryopreservated boar semen is 54.3% and 48.2%, showing no significant difference with fresh-ejaculated semen.Experiment 4. Application of LDL as a cryoprotectant.The protocol of extraction of LDL from egg yolk were studied. And we succeeded in extracting LDL from egg yolk. But when using it as cryoprotectant, we found it can't be resolved in water. Then we found an easy method to use LDL. We use different concentrations of concentrated egg yolk to cryopreservat boar semen, and found the effect is not better than egg yolk.