Economic evaluation of risks to producers who use milk residue testing programs

Procaine penicillin G (PPG) disappearance curves were generated for cows given a single i.m. dose of PPG 6600 U/kg or 26 400 U/kg, or multiple doses of 26 400 U/kg using meta-analysis of the Food Animal Residue Avoidance Databank. These curves were entered into 1000 computer simulated cow models to obtain population-level milk PPG profiles. A 2-day withdrawal period avoided violative residues in both single treatment groups but nearly 2/3 of the cows risked false identification for violative residues. For the multiple treated group, nearly 40% had violative residues after a 5-day withdrawal period and an additional 10 to 15% risked false identification for these residues. Economic analysis yielded a decision against testing. The mean cost was $2, i.e. 5% more than the mean cost of not testing.