BILLINGS — Montana is ‘‘clear of bison’’ after 51 of the animals were released back into Yellowstone National Park over the weekend, National Park Service and Montana Department of Livestock officials said.

The release of bison captured west of the park capped a monthlong saga in which state officials talked about sending to slaughter hundreds of bison that strayed from Yellowstone, including up to 100 calves.

Because some bison carry brucellosis, a disease that causes infected pregnant animals to abort their young, Montana officials have been trying to remove bison from areas with cattle prior to the start of the summer grazing season.

After the slaughter plan prompted a public outcry, state officials forged an agreement with the National Park Service to load the animals onto trucks and drive them back inside the park.

‘‘It’s quite different (from earlier plans) and best for all involved,’’ said Christian MacKay, Department of Livestock executive officer. ‘‘Montana is clear of bison. Everybody is knocking on wood and hoping they stay in there.’’

A recent brucellosis outbreak among some cattle in Bridger put the state’s disease-free status in jeopardy. If another infected herd is found, the livestock industry faces a costly and prolonged program of testing and vaccination.

Tim Reid, Yellowstone deputy chief ranger, said bison near the park’s west boundary park would be pushed even deeper into Yellowstone on Tuesday, to preclude any chance of contact with livestock.