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 effi­cacy was determined using the Global index (GI), Anticoccidial Sensitivity Test (AST) and Opti­mum 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 conti­nuous use of anticoccidials in the field, altering the prevention strategy and rotation of the anticocci­dials with better efficacy, would prevent further economic losses induced by coccidiosis.

Keywords

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