A producer shall pay a levy on an agricultural product produced by him at such rate as the Minister may, subject to the provisions of subsection (4), prescribe. "Agricultural product" means: (a) dry maize on or off the cob, milk and butterfat; and (b) any other animal or any thing whatsoever which is produced in the course of agriculture declared, pursuant to subsection (2) of section 5, by the Minister, by statutory order, to be an agricultural product for the purposes of this Act. The Minister