The commissioner of agriculture shall grant such state aid only on cash premiums paid on approved classes of:
(1) Cattle, swine, sheep, goats, farmwork stock, including mules shown to halter or farm vehicles, jack stock and light horses to halter;
(2) Poultry, eggs, and dairy products;
(3) Field, garden and horticultural products;
(4) Home economics displays;
(5) Junior agricultural projects; and
(6) Agricultural educational exhibits.