Study On Cryopreservation Of Boar Semen

Artificial insemination (AI) in bovine and ovine with freezing-thawed semen had been more and more widely applied to livestock reproduction, but researchers haven’t found a feasible way on cryopreservation of boar semen. This study was designed to investigate some issues on boar semen cryopreservation, including addition of different concentrations of equex in BF5, different kinds of thawing solution, different freezing methods and boar individual differences, to find the best equex concentration, thawing solution and freezing methods by comparing the motility of thawed sperm, the percentage of sperm with integrity acrosome and blastocyst formation.1. The investigation of boar semen crop reservation method1.1Effects of different Equex concentration on sperm motility and acrosome integrityThe boar semen was frozen by dry ice/pellet method with different concentration of equex (0、0.4%、0.5%、0.6%) to find the best equex concentration in BF5. The results showed the motility (0.14) and percentage of sperm with integrity acrosome (40.03%) of the group without equex were significantly lower than three groups with equex, and the motility (0.24) of0.5%equex group was significantly higher than0.4%and0.6%equex groups (0.21and0.20)(P<0.05). The percentage of sperm with integrity acrosome of0.6%equex group (58.39%) was higher than0.5%equex group (57.92%), but it was not significantly, both these two groups were significantly higher than0.4%group (51.70%). So0.5%equex was the best concentration in BF5.1.2Effects of different thawing solution on sperm motility of frozen-thawed boar semenWe selected three batches of boar semen frozen by BF5with0.5%equex, and thawed with glucose-EDTA solution and PBS-BSA solution respectively. The result showed the motility (0.22) of semen thawed with glucose-EDTA solution was significantly higher than PBS-BSA solution (0.13)(P<0.05).1.3Effects of different cry op reservation methods on sperm motility and acrosome integrityThree different methods (dry ice/pellet, liquid nitrogen/pellet and liquid nitrogen/straw) were tested to freeze boar semen. The sperm motility and the percentage of sperm with integrity acrosome were compared after thawing in the same way. The motility of sperm frozen by dry ice/pellet (0.23) was higher than liquid nitrogen/pellet (0.20). Both of them were significantly higher than liquid nitrogen/straw (0.08)(P<0.05). The percentage of sperm with integrity acrosome in dry ice/pellet group (58.0%) was significantly higher than both in liquid nitrogen/pellet group (54.7%) and in liquid nitrogen/Straw (54.2%) groups (P<0.05).1.4Effects of different individuals on sperm motility and acrosome integrityWe selected three boars which had stable natural mating record and success rate of artificial insemination followed by freezing-thawing their semen and comparing motility and acrosome integrity of sperm. The results indicated there were no differences in the percentages of sperm with integrity acrosome, but the motility of sperm is significantly different between three boars.2. In vitro fertilization with frozen-thawed boar semen2.1Effects of on frozen-thawed boar semen on In vitro FertilizationThe sperm frozen by dry ice/pellet method and thawed in glucose-EDTA were used for IVF. The results indicated that there was no significant difference in blastocyst formation between frozen semen (17.6%) and fresh sperm (17.9%), but both of them were significantly lower than parthenogenetic activation (36.6%)(P<0.05).2.2Effects of different individuals derived semens on in vitro fertilizationThree boars (0101,1001and2101) were selected for expeiment, and their fresh and frozen-thawed semen were used for IVF respectively.In the experiment of IVF by fresh semen, blastocyst formation of0101(17.9%)was significant higher than1001(9.0%), both were significant higher than2101(0%)(P<0.05); In the experiment of IVF by frozen-thawed semen, blastocyst formation of0101 (17.6%) was significant higher than1001(4.0%), and both of them were significant higher than2101(1.1%)(P<0.05). Individual differences would lead to different results on in vitro fertilization.3. Artificial insemination of frozen-thawed semenThe semen of three boars frozen by dry ice/pellet method and thawed in glucose-EDTA solution was used for artificial insemination (AI) respectively. Three porcine were deal with AI. One porcine was estrus for one time after AI and did not find fetus after butcher. The others were not estrus, but did not find fetus after butcher.Taken all results together,the dry ice/pellet combined with0.5%Equex in BF5and glucose-EDTA thawing solution might be the appropriate method for boar semen cryopreservation. The frozen sperm derived IVF embryos showed same blastocyst formation potential compared with fresh sperm derived IVF embryos. However, artificial insemination with the frozen boar semen needs to be investigated.