Background: In this study, the presence of resistance to diclazuril, amprolium+ethopabate and salinomycin, representing some of the commonest anticoccidials in Iran’s poultry industry, against three mixed Eimeria field isolates were investigated.
Methods: Three Eimeria field isolates, collected from typical broiler farms in Iran, were propagated once, inoculated to 480 broilers, comprising 30 chicks in each treatment. The non-medicated or medicated diets containing one of the above mentioned anticoccidials were provided ad-lib. Drug ef-ficacy was determined using the Global index (GI), Anticoccidial Sensitivity Test (AST) and Opti-mum Anticoccidial Activity (OAA).
Results: None of the field isolates were fully sensitive to the selected anticoccidials. All isolates showed reduced sensitivity/partial resistance to salinomycin. Resistance to amprolium+ethopabate was evident and partial to complete resistance was recorded for diclazuril.
Conclusion: Limited efficacy of the selected anticoccidials is obvious. Considering the cost of conti-nuous use of anticoccidials in the field, altering the prevention strategy and rotation of the anticocci-dials with better efficacy, would prevent further economic losses induced by coccidiosis.