About 130 mares recently received a vaccine expected to preventpregnancy as part of a national wild horse fertility-control pilotproject for the Bureau of Land Management, according to Dr. Irwin K.M. Liu, a professor of reproduction at the UC Davis School of Veterinary Medicine. Liu, whose primary research interest focuses on enhancing fertility in horses, first developed and tested the vaccine in 1984. He hoped it would provide a better way of managing wild horse populations than current methods. Since then, the contraceptive vaccine has been over 95 percent successful in two populations of wild horses in Maryland and California. The vaccine lasts one breeding season, or about one year, with no side effects when boosted every 2-3 years. Research collaborators in Ohio and Montana are also using the vaccine to control deer populations in Virginia, Ohio and California, as well as in captive populations of related species in zoos. Liu hopes to test the vaccine soon in elephants in Asian and African countries. He also is working on a longer-term contraceptive.