Montana officials plan to vaccinate bison roaming beyond Yellowstone National Park's western border to prevent the potential spread of brucellosis from infected bison to cattle, but environmentalists say the vaccine doesn't work well in the animals.
The Montana Department of Livestock proposes to vaccinate up to 200 animals annually. It would expand a program started last winter when the National Park Service treated 114 bison inside the park.
Officials round up bison outside the park. Nearby ranchers fear brucellosis will infect herds and cause other states to ban Montana beef.
But a draft environmental study says not enough bison would be vaccinated to reduce the risk of spreading disease.
Brucellosis causes female bison, cattle and elk to abort their first pregnancies and spread the brucella bacteria.
-- Rebecca Huntington