Mich. Comp. Laws § 288.650

Sec. 90. (1) The director, after proper identification, is authorized and shall have the power to enter all dairy farms, dairy plants, single service manufacturing facilities, milk tank truck cleaning facilities, receiving stations, transfer stations, dairy product distribution facilities, vehicles used to transport milk and milk products or single service manufacturers under its jurisdiction, for the purpose of inspecting, sampling, and investigating conditions relating to the enforcement of this act. (2) The department shall, at a minimum, inspect all dairy farms every 12 months and dairy plants, receiving stations, and transfer stations every 6 months, or at time intervals as specified by the director.