Ala. Code § 3-2-20

The Director of Public Safety shall provide for taking up and impounding livestock or animals running at large upon state and federal aid highways which have been officially designated as such and regularly and customarily patrolled by the state highway patrol or upon the rights-of-way of such highways and, to that end, within the limit of the funds provided by this article, the Director of Public Safety is hereby authorized and empowered to contract with persons, firms or corporations within the several counties to take possession of and impound such livestock or animals.