California Code, Revenue and Taxation Code - RTC § 6075

(a) No permit shall be required of any person who engages in business in this state as a seller of feed, for any form of animal life, that is exempt from taxation pursuant to subdivision (b) of Section 6358 and who engages in no other taxable sales of tangible personal property at retail.

(b) In the case of any seller of hay who is also a grower of hay, the exemption provided in subdivision (a) shall apply only to growers who are either of the following:

(c) Nothing in this section shall relieve any grower of hay that is not exempt pursuant to subdivision (b) of Section 6358 from obtaining a permit.