The effect of using long term and short term extenders during cooling process on the quality of frozen boar semen

Cooling process of cryopreservation is one of the important factors that affect the qualities of frozen-thawed boar semen. The objective of this study was to compare the qualities of frozen-thawed boar semen after using different extenders (i.e. BTS, Vitasem LD, Modena™ and Androstar® plus) during cooling process. Eight sperm-rich fractions from 8 boars were employed. The ejaculated semen sample from each boar was divided into four groups and extended in different freezing extender I as follows: group I (control, short term, BTS), group II (long term, Vitasem LD), group III (long term, Modena™) and group IV (long term, Androstar® plus) and kept at 15°C for 2 hours (so-called cooling process) before cryopreservation. Thereafter, the semen samples were further evaluated for semen qualities at 2 hours post-cooling and also after post-thawing. For post-cooling, the highest percentage of motility and viability were found in treatment groups (II, III and IV) compared with control group (p<0.05). For postthawing, the highest percentage of motility was found in groups I and II. A tendency of higher percentage of viability was found in treatment group IV than control group. In conclusion, in the term of progressive motility and viability, the results indicate that using long term extenders as freezing extender I during the cooling process yields a superior semen quality at post-cooling than using short term extender.