Update 8:45 a.m.
The cattle are no longer on the highway, according to the Montana Department of Transportation.
A large herd of cattle slowed traffic on Interstate 90 near Lodge Grass on Thursday morning, according to the Montana Department of Transportation.
About 100 cow and calf pairs were roaming on the highway about 2 miles southeast of the Lodge Grass interchange between mile markers 535 and 536 at about 7:45 a.m.
The Big Horn County Sheriff's Office and state employees were in route, the agency said.
Motorists in the area should reduce speeds and expect delays.