Mont. Code Ann. § 81-4-506

All abandoned horses taken up in a roundup must be delivered to the roundup supervisor in charge of the roundup and must be offered by the supervisor for sale at public auction and sold to the highest bidder for cash, if there is any bidder, and any abandoned horses offered for sale and for which no bid is made must be destroyed or otherwise disposed of in the discretion of the board of county commissioners unless reclaimed as provided in this part.