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

The main limiting factors for a wider use of frozen-thawed (FT) boar semen are low fertility levels of FT in comparison with liquid semen, and between-boar variation in freezing success. Consequently, there is a need for improved boar semen freezing methods. The objective of the study was to determine the effect of addition a-tocopherol and caffeine to the freezing extender on boar semen qualities and fertility capacity. The main objective of this thesis was to develop a method for freezing of boar semen, and the study of the effect of different factors on boar sperm survival in vitro and fertility after freezing-thawing in large, one-AI-dose containers. Semen was split-sample frozen in 0.5mL straws. sperm viability after thawing and low fecundity rates after artificial inseminations. we get the following conclusions:1. Addition caffeine to the freezing extender can improve boar semen qualities and fertility capacity. The effective concentration of Caffeine in freezing extender was 0.2 mg/mL.2. The data revealed that the effect of supplemented with alpha-tocopherol in extender on improving kinematics parameters,protecting sperm plasma membrane integrity,acrosome integrity and increasing the sperm fertilizability after freeze-thawing.In conclusion, a-tocopherol, supplemented at 400μM concentration in boar semen extender during cryopreservation had a positive effect on post-thawed sperm survivability.3. We determinated the best frozen program. Straws (0.5mL) filled with the cooled semen in a cold cabinet,were frozen in a programmable freezer from 5℃to -5℃at 2℃/min, holding at -5℃for 1min, and thereafter cooled to (-140℃) at 60℃/min. Straws were then plunged into liquid nitrogen (-196℃) for storage. Adopting optimized freezing and thawing protocol increased the quality of thawed semen, meanwhile, thawing at 38℃for 30 s or 50℃for 13s were the optimal protocol.4. Frozen-thawed (FT) boar semen are low fertility levels of FT in comparison with liquid semen. Frozen boar semen pregnancy rate was 72%, litter size is 6.64±0.82. No significant difference was found for the effect of two volume(60mL and 80mL) used for insemination. In conclusion, frozen boar semen can be used successfully by using IUI catheter (a dose of 2x10~9 spermatozoa, diluted with 60 mL of semen extender) .