The feed manufacturer may not substitute a generic VFD drug in a combination VFD feed if the generic VFD drug is not part of an approved combination VFD drug.

• A. False
• B. It depends on batch testing
• C. True
• D. Only if the producer requests

Answer: (C)

Under VFD rules, you must use only the exact drug products and combinations named in the VFD order. A substitute that isn’t included in the approved combination isn’t permitted because the VFD framework ties authorization, withdrawal times, and labeling to the specific product listed. If a producer wants to use a generic that isn’t part of the approved combination, they’d need a new or amended VFD that includes that product, or switch to an approved combination.

Batch testing, producer requests, or other informal pathways don’t override that requirement, since approvals are product- and combination-specific.