CFR›Title 21›Chapter I›Part 558 ContainsSubparts A–BCorpusDaily eCFRDisplayed edition2026-04-24Last updated2026-04-24 PART 558—NEW ANIMAL DRUGS FOR USE IN ANIMAL FEEDS Subparts A Subpart A—General Provisions Sections 558.3–558.6 B Subpart B—Specific New Animal Drugs for Use in Animal Feeds Sections 558.55–558.680 Authority21 U.S.C. 354, 360b, 360ccc, 360ccc-1, 371.Source40 FR 13959, Mar. 27, 1975, unless otherwise noted. Previous 556 Part 556—Tolerances for Residues of New Animal Drugs in Food Next 570 Part 570—Food Additives