CFR›Title 21›Chapter I›Part 558›Subpart A ContainsSections 558.3–558.6CorpusDaily eCFRDisplayed edition2026-04-24Last updated2026-04-24 Subpart A—General Provisions Sections 558.3 § 558.3 Definitions and general considerations applicable to this part. 558.4 § 558.4 Requirement of a medicated feed mill license. 558.5 § 558.5 Requirements for liquid medicated feed. 558.6 § 558.6 Veterinary feed directive drugs. Next B Subpart B—Specific New Animal Drugs for Use in Animal Feeds