Comparative study on six different long term commercial extenders for fresh boar semen

In Thailand, there are numerous commercial extenders for preservation of boar semen; however, no study has been carried out to compare these extenders in view of maintaining of sperm motility, plasma membrane integrity and acrosome integrity during cold storage. The aim of this study was to assess the percentage of sperm motility, HOST positive, viability and acrosome integrity of boar spermatozoa extended in Merck-III, Androstar^®Plus, Modena^TM, NUTRIXcell^®, VITASEM LD, Duragen and Dofu gold^TM. Ejaculated from boars (n=6, one ejaculate from each boar) were collected and sub-samples (splited samples) were diluted (3 × 10⁹ spermatozoa/100 ml) in the different extenders and stored for 10 days at 18°C. On every second day (days 0, 2, 4, 6, 8, 10) after storage, the sperm parameters such as sperm motility, HOST positive, viability and acrosome integrity were evaluated. There were significant differences in characteristic of sperm motility and acrosome integrity between extenders. For instance, on day 4, Merck III (short term extender) and other long term extenders are able to maintain the semen qualities as claimed by the manufacturing. On day 8, the percentages of sperm motility, viability and acrosome integrity were highest (p< 0.01) in Androstar^®Plus (72%) and Modena^TM (75%), Androstar^®Plus (67%) and Modena^TM (65.6%), and Androstar^®Plus (74.6%), Duragen (72.4%) and VITASEM LD (71.6%), respectively. In conclusion, changes in motility, viability and acrosome integrity during storage were affected by the extender utilized, however long term extenders maintained a high percentage (70%) of sperm motility (i.e. Androstar^®Plus, Modena^TM and Duragen) and acrosome integrity (i.e. Androstar^®Plus, VITASEM LD and Duragen) through 8 days of storage.