Vaccination to Control Brucellosis in Free-Ranging Elk on Western Wyoming Feed Grounds

Abstract

Approximately 22 500 elk (Cervus elaphus nelsoni) are fed during winter months at 23 feed grounds in Wyoming to reduce winter mortality and depredation on agricultural crops. Brucellosis was documented on 18 feed grounds and seroprevalence among adult females averaged 37% (range 16 to 50%). Non-fed elk populations were generally free of brucellosis. Strain 19 Brucella abortus vaccine was shown to reduce infection and abortion in elk. A vaccination programme was initiated to increase calf production and decrease the potential of transmission of the disease to livestock. An airgun was used to implant a methylcellulose pellet containing lyophilized vaccine in muscle tissue. Vaccinated elk were marked with a gelatin-encased, oil-base paint ball. Elk were first acclimatized to human activity and then to the report of the airgun through repeated dry-firing at gradually increased volumes. Cow and calf elk were marked and vaccinated from feed sleds as they fed on hay. Over 13 000 doses were administered during 1985-1990 on 9 feed grounds. An estimated 4700 elk were vaccinated during winter 1990, including an average of 95% of calves on 8 feed grounds and 72% of cows on 4 feed grounds.