It is declared to be the law of this State, pursuant to paragraphs (h) and (i) of Section 6 of Article VII of the Illinois Constitution that the regulation of dairy farms, milk plants, cleaning and sanitizing facilities, receiving stations, transfer stations, milk tank trucks, milk hauler-samplers, and certified pasteurizer sealers is an exercise of exclusive State power which may not be exercised concurrently by a home rule unit unless provided otherwise in Section 4 of this Act.