Montana Ag Network: Some Ranchers Frustrated with BLM Decision on Wild Bison MTN and last updated 2021-07-05 01:10:12-04 BILLINGS â The Montana Stockgrowers Association (MSGA) is expressing disappointment in the release of BLMâs draft environmental assessment finding no significant impact for a bison grazing proposal submitted by the American Prairie Reserve (APR). Montana Ag Network: Some Ranchers Frustrated with BLM Decision on Wild Bison MSGA vice president Jay Bodner says in recent years, MSGA has raised a variety of concerns with APRâs request to BLM to change the class of livestock from cattle to bison, change the authorized seasons-of-use, and the removal of interior fences.