HELENA, MONT., DEC. 28 -- State wildlife officials have put off a decision on a temporary plan to kill wandering bison from Yellowstone National Park to ensure that they do not spread disease to cattle.

The plan, which was the subject of a hearing Thursday, includes a provision to have federal rangers help state wardens kill cows that wander outside the park.

Officials have said that cows are more likely than bulls to carry the disease brucellosis and that putting responsibility for their killing in the hands of wardens and rangers should reduce chances of spreading disease.

About half of the 2,500 to 3,000 bison in the 2-million-acre park are believed to carry brucellosis, which causes cattle to abort. Montana spent millions of dollars over a decade to eradicate brucellosis in its cattle.

Hunters would continue killing bulls outside the park, and calves would be captured, sterilized and sold at auction.

Animal-rights groups are lined up solidly against killing the animals, contending that the threat of passing brucellosis from bison to domestic cattle is minimal or nonexistent.

The Montana Department of Livestock and the Montana Stockgrowers' Association are equally adamant in demanding that bison not be allowed even the slightest chance to contaminate public and private range land abutting the park's northern and western boundaries.

The plan has caused a furor this winter, with critics, including sport hunters, complaining that killing the bison has wounded Montana's reputation as a refuge for wildlife.

"Let's get hunters out of the business of shooting bison," Brian Kahn of Helena said at Thursday's hearing.

Knute Hereim, a rancher from Martinsdale representing the stockgrowers' association, said livestock producers support the state's attempt to keep infected bison from possibly reinfecting Montana herds.

He said officials in Yellowstone have not taken steps to control the animal health risk. "Immediate action must be taken," he said.

Pat Graham, associate director of the state Department of Fish, Wildlife and Parks, said all comment submitted at Thursday's hearing, a previous hearing Dec. 14 and written comment would be assessed before a final decision is made, probably next week.

Graham said there is no immediate threat of hundreds of bison moving from the park into Montana, giving the department longer than originally anticipated to make its decision.

During both public hearings this month and in written comment, the National Park Service has been criticized for not controlling bison movements or cleansing the herds of brucellosis.

So far this winter, only hunters have been used to kill bison wandering across the park's border in the region near West Yellowstone. Eleven bulls have been killed. Two seasons ago, 569 bison were killed.