Guide
Veterinary Feed Directive & 21 CFR 225/558: A Practical Readiness Guide for Medicated Feed
Medicated feed manufacturing in the United States operates under 21 CFR Part 225 cGMP for medicated feeds, 21 CFR Part 558 new animal drugs for use in animal feeds, and the Veterinary Feed Directive (VFD) at 21 CFR 558.6 which channels medically important antimicrobials through veterinarian prescription. The 2017 VFD final rule and the 2023 GFI #263 transition of remaining over-the-counter medically important antimicrobials to prescription/VFD status have made the VFD framework the central regulatory question for any feed mill handling antimicrobials. This guide walks the integrated 225/558/VFD framework, the recurring inspection findings, and a practical path to a defensible medicated feed programme.
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Type A vs Type B vs Type C — and which licensure applies
21 CFR 558 defines three medicated feed types. Type A Medicated Articles (drug premixes) are manufactured under the new animal drug approval and require an FDA Medicated Feed Mill Licence under 21 CFR 515 for facilities producing certain higher-risk Type B/C feeds. Type B intermediate feeds and Type C complete feeds may be produced licensed or unlicensed depending on the Type A used and the labelled categories. The licensure decision drives the inspection model and the recordkeeping requirements — a mill operating under the wrong licence assumption is a recurring finding.
VFD recordkeeping and the manufacturer-distributor-veterinarian-producer chain
21 CFR 558.6 requires a written or electronic VFD authorising every medically important antimicrobial use in feed. The original VFD must be retained by the issuing veterinarian; copies are retained by the distributor and the client (producer). All three parties retain VFD records for at least 2 years. Recurring inspection finding: the distributor copy is on file but cannot be retrieved by lot, client or veterinarian on the inspector's timeline; or the VFD expiration date has lapsed but distribution continued.
Assay, carryover and the 21 CFR 225 inspection model
21 CFR 225 cGMP for medicated feeds requires drug assay on each batch or per a CVM-approved sampling plan, validated mixing uniformity, validated cleanout between medicated and non-medicated runs, and the carryover/sequencing controls that prevent unintended drug contamination of subsequent feeds. Recurring finding: a sequencing plan exists but is not followed; or a cleanout is performed but the verification (sampling and assay) is not on a defensible interval.
GFI #263 and the antimicrobial stewardship overlay
GFI #263 (implemented 2023) moved the remaining medically important antimicrobials for animal use from over-the-counter to prescription/VFD status. The implementation reshaped distribution patterns and made every dispensing event require either a prescription (injectable, oral solutions/tablets) or a VFD (medicated feed). The post-2023 inspection focus on antimicrobial stewardship — appropriate-use documentation, duration limits, label compliance — has intensified. Audit trails that look adequate against the pre-2023 rules may be deficient against current expectations.
A 60-day readiness path for FDA feed inspection
Days 1–10: licensure scope check — Type A/B/C, Medicated Feed Mill Licence applicability. Days 11–25: VFD recordkeeping audit with retrieval-by-multiple-dimensions test. Days 26–40: sequencing/carryover/cleanout verification audit with assay reconciliation. Days 41–50: GFI #263 antimicrobial stewardship overlay review. Days 51–60: internal cGMP audit, management review and FDA inspection readiness rehearsal.
Standards covered in this guide
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Where this lives in V5 Ultimate
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Frequently asked
Does every medicated feed mill need a Medicated Feed Mill Licence?
No — the licence is required for facilities producing certain Type B and Type C feeds containing specified Category II Type A medicated articles. Many mills operate unlicensed under the Category I framework. The 21 CFR 515 listing defines which combinations trigger licensure.
How long is a VFD valid?
The expiration date is set by the issuing veterinarian and cannot exceed 6 months from issue. Some specific drugs have shorter mandatory expiration windows defined by the approved use. Distribution against a VFD past its expiration is a regulatory violation.
What changed with GFI #263?
All medically important antimicrobials for animal use moved from over-the-counter to prescription/VFD status, completing the transition begun in 2017. Producers can no longer purchase these products over the counter — every use requires a veterinarian's prescription (injectable/oral) or VFD (feed).
Does the VFD apply to ionophores?
No — ionophores (monensin, lasalocid, salinomycin) are not classified as medically important antimicrobials and remain non-VFD. They are subject to 21 CFR 558 medicated feed rules and 21 CFR 225 cGMP but not the VFD authorisation requirement.
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