Evaluating the Resistance of Eimeria Spp. Field Isolates to Anticoccidial Drugs Using Three Different Indices

Abstract

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.

Keywords

• Anticoccidial Sensitivity Test
• Drug resistance
• Eimeria
• Global Index
• Optimum Anticoccidial Activity