The secretary may constitute as his agent, for the purpose of inspecting milk or milk products, a department of health, board of health or health officer of any municipality, or the county department of health of any county or counties which have established or joined in establishing such a department, and may accept inspections by municipalities or county departments of health, under the terms of municipal ordinances or county department of health regulations equally as stringent as the requirements of this act and enforced by such municipalities or counties, as the only inspection required for the sale of milk or milk products in such municipalities or counties.
31 P.S. § 649