Mont. Code Ann. § 81-4-104

The owners of barbed wire fences shall keep the same in repair, and a person who receives notice in writing that the person's barbed wire fence or any part of the fence is down or in such condition as to be likely to injure any livestock and who fails or refuses to repair the fence is liable to pay damages in an amount equal to the value of any cattle, horses, mules, or other domestic animals that may be injured by coming into contact with the fence.