**6. Boar semen cryopreservation**

solution, the higher the rate of lipid peroxidation as measured by malonaldehyde produc‐ tion [24]. In boar, total antioxidant in seminal plasma relates to percentage of normal sperm morphology and plasma membrane. The low storability semen has presented the high plas‐ ma membrane damage from ROS, which was resulted from low amount of antioxidant in seminal plasma [2]. Moreover, the semen which having poor normal sperm morphology has

The balance between these key factors determines the overall rate of peroxidation in vitro. In this system, the substrate seems to play a key role. The main substrates for lipid peroxida‐

The glutathione peroxidase is main intracellular antioxidant enzyme that catalyses to reduce the hydrogen peroxide and organic hydroperoxides to nontoxic metabolized compounds. The essential component of this enzyme is selenium. Vitamin E or alpha-tocopherol is the dominant antioxidant in cell plasma membranes. Many researches have shown a synergism of antioxidant activity between selenium in glutathione peroxidase and vitamin E. The ef‐ fects of selenium supplementation on semen quality were more reported than the effects of vitamin E supplementation, and selenium supplementation improved in higher conception rates when gilts were serviced with extended semen from the boars [33]. However, feed ad‐ ditive on boar diet with high levels of vitamin C had no effects on semen quality or libido characteristics in healthy boars. U.S. Food and Drug Administration (FDA) regulations al‐

Vitamin C or ascorbic acids are a dominant water-soluble antioxidant. Their action is scav‐ enger to disable the function of any type ROS. Vitamin C is a powerful source of electron donor which reacts with hydroxyl radicals, peroxide and superoxide to form de-hydroxyl ascorbic acid. The level of ascorbic acid in seminal plasma is approximately 10-fold higher concentration comparing with blood plasma in human [30,34]. The level of ascorbic acid in

Linoleic acid or omega-6 fatty acid is the only FA for which NRC has established require‐ ments at least 0.1% of diet for sexually active boars. However, the effect of various fatty acids (FAs) top on diet, particularly the omega-3 fatty acids, on semen quality and libido characteristics in boars are more interesting. Nowadays, there are 3 types of omega-3 fatty acids that are linolenic, eicosapentaenoic (EPA) and docosahexaenoic (DHA). The boar feed commonly consist of the large amounts of crops, with source of protein added in the form of soya-bean, fish powder, bone powder, etc. Thus, dietary fatty acids have a (n-6):(n-3) normal ratio of greater than 6:1 and do not contain long chain n-3 PUFAs. If 22:6(n-3) is essential for

seminal plasma has a positively correlation with the percentage of normal [35].

shown the low level of antioxidant in seminal plasma (Table 1) [1].

20 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed

tion are polyunsaturated fatty acids, especially docosahexaenoic acid.

low up to 136 g of selenium add on/pound of feed for pigs.

**5. Effect of Polyunsaturated Fatty Acids (PUFAs)**

**4. Effect of vitamins and minerals**

The research on semen cryopreservation in boar is limited even though the procedures have been studied during the past 60 years [43-47]. The advantages for development of frozen se‐ men include the preservation of the good genetic resource, the distribution of superior ge‐ netic boars, and the improvement of the transportation of sperm across countries [48]. However, the utilization of frozen-thawed (FT) semen prepared for artificial insemination (AI) at present is estimated to be less than 1% of all insemination worldwide. The most im‐ portant reasons are the poor sperm quality after cryopreservation and a lower fertilizing ca‐ pacity of FT semen, when used for conventional AI compared to fresh semen. Poor sperm quality frequently found in FT boar semen is partly due to a high sensitivity of the boar sperm to rapid cooling to a few degrees above 0C, the so-called "cold shock", which the sperm have to traverse during cryopreservation process. This is evidenced by the loss of via‐ ble sperm and by more capacitation-like changes in the viable sperm [49]. These changes re‐ sult in a shorter survival time of the FT sperm in the female genital tract in comparison to its fresh and liquid-preserved counterparts [50,51].
