Withdrawal times have been established for most antimicrobial products for feed an therapeutic use. If residues are found in carcasses, the farm can be quarantined. During quarantine, producers are required to supply test animals without compensation and pay all lab fees until carcasses have been proven to be free of the residues. No animals can be sold for market during the quarantine period. This can be very costly for large operations and can lead to space problems as no room can be made for younger animals.
Most residues come from contaminated feeds.
Be careful not to cross-contaminate feed batches. Thoroughly empty all feed mixing, storage, and transporters after exposure to drugs or feeds containing drugs. Following a logical feed-mixing sequence to lower contamination in animals approaching market weight. Mix feed components thoroughly, but do not overmix. It is illegal to use powdered sulfa drugs.