In 1995, Dr. Mennick visited two large, commercial boar studs in Iowa, and discussed the latest cryopreservation techniques with them. P.I.G. also has at least one boar in residence at all times, providing semen mostly for local 4H and FFA projects.  Boars are easily trained to a "dummy" as a stallions, and are thus easy to collect semen from.

Several extenders are available commercially for both fresh and frozen semen use; as with stallions, we test several of our own homemade extenders as well for best results. While decidedly the most expensive commercial extender, we have used Androhep for much of our fresh-chilled semen shipping because it usually provides the best sperm longevity. The extender we end up using to freeze semen with is more variable from boar to boar.

Boar semen is unique among the domestic species in that it survives processing best at temperatures different from other species. Fresh semen stores best at 62 degrees F (17 degrees C). To prevent rabid bacterial growth, we add the typical CSS "cocktail" of gentamicin, lincomycin, tylosin, and spectinomycin. Storage is effected in a special refrigerator modified to maintain the proper storage temperature. We also store our "blue-ice" packs in this refrigerator, so that samples shipped out are packed in an insulated, styrofoam box containing these packs at the proper temperature.

When freezing boar semen, it seems to survive best when chilled at a rate neither "fast" nor "slow". Even more unusual is the fact that upon thawing, it often looks completely dead. In fact, it may take a full hour for the thawed sperm to regain full motility upon incubation! Because of the large numbers of sperm required for good pregnancy rates (at least 3 billion), we freeze in either 5ml Macrotubes, or multiple small straws (0.5ml)  to constitute a dose. As with all female animals bred with frozen semen, the TIMING of insemination is the most critical factor, and we suggest three inseminations 8 hours apart when using frozen semen in sows.