Economic evaluation of risks to producers who use milk residue testing programs.
OBJECTIVE
To evaluate the decision to test for milk antimicrobial residues in milk from dairy cows treated with procaine penicillin G (PPG).


METHODS
Economic-decision analysis after stochastic simulation.


METHODS
1,000 computer-simulated cows/model.


METHODS
Meta-analysis of the Food Animal Residue Avoidance Databank was used to generate PPG disappearance curves for cows given single PPG treatments, IM, of 6,600 U/kg (3,000 U/lb) of body weight or 26,400 U/kg (12,000 U/lb), and multiple treatments at 26,400 U/kg (12,000 U/lb), IM. These curves were entered into 1,000-replication stochastic pharmacokinetic models, generating population-level milk PPG profiles for each treatment group for each day after treatment, which were subjected to economic-decision analyses of feasibility of residue testing. The model was evaluated for changes in herd size, proportion of herd available for testing, milk production, test price, test sensitivity/specificity, and withdrawal periods.


RESULTS
For both single-treatment groups, a 2-day withdrawal period avoided violative residues. However, nearly two thirds 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 violative residues. Economic analysis yielded a decision against testing; mean cost was $2 (ie, 5% more than the mean cost of not testing).


CONCLUSIONS
Complex dynamics of current milk residue tests discourage practitioners from recommending procedures to clients. In general, increases in herd size, milk production, proportion of a herd available for testing, or milk price will increase the value of testing. Increasing test sensitivity decreases its desirability to producers.
Slenning
B D
BD
Department of Food Animal and Equine Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh 27606, USA.
Gardner
I A
IA
D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D003612:Dairying / Q000191:economics*; D016208:Databases, Factual; D004350:Drug Residues / Q000032:analysis* / Q000493:pharmacokinetics; D005260:Female; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D010402:Penicillin G Procaine / Q000032:analysis* / Q000493:pharmacokinetics / Q000627:therapeutic use; D010406:Penicillins / Q000032:analysis* / Q000493:pharmacokinetics / Q000627:therapeutic use; D011237:Predictive Value of Tests; D018570:Risk Assessment; D013269:Stochastic Processes
D010406:Penicillins; D010402:Penicillin G Procaine