The
cryoinjury is mainly affected by the formation of ice
crystal within the sperm cell during cryopreservation,
while the temperature shock is caused by a rapid
reduction of the temperature during either cooling
and freezing processes. Therefore, a cryoprotective
agent is necessary. Currently, the most common
cryoprotectant of the boar sperm is 3.0% glycerol
(Kim et al., 2011). During the present time, the FT boar
semen technology is rapidly developed with special
emphasis on genetic preservation and the distribution
of a good genetic resource worldwide. Our recent
study has demonstrated that the modification of the
semen extender can significantly improve the postthawed
boar semen qualities (Chanapiwat et al.,
2009b). Generally, the sperm-rich fraction of the
ejaculated boar semen is extended in a commercial
extender for at least 2 hours at 150C before
cryopreservation, so called “holding time”(Eriksson et
al., 2001). It has been demonstrated that the length of
the holding time significantly influences post-thawed
sperm qualities (Guthrie and Welch, 2005).