21 C.F.R. § 510.305
Maintenance of copies of approved medicated feed mill licenses to manufacture animal feed bearing or containing new animal drugs
Each applicant shall maintain in a single accessible location:
(a) A copy of the approved medicated feed mill license (Form FDA 3448) on the premises of the manufacturing establishment; and
(b) Approved or index listed labeling for each Type B and/or Type C feed being manufactured on the premises of the manufacturing establishment or the facility where the feed labels are generated.