RESISTANCE TO DICLAZURIL IN-FIELD ISOLATES OF EIMERIA SPECIES OBTAINED FROM COMMERCIAL BROILER FLOCKS IN BRAZIL

The efficacy of the anticoccidial drug diclazuril against field isolat es of Eimeria spp. collected from broiler farms in four different site s of the South and Southeastern regions of Brazil were investigated. T he effect of the drug was measured by an assessment of weight gain, le sion score and oocyst production. Two reference laboratory strains not previously exposed to diclazuril were sensitive to the drug. Two fiel d isolates were judged to be sensitive to diclazuril, four were partly resistant and six were resistant to the drug. The response of the iso lates to diclazuril varied depending upon the extent of exposure and t ype of drug programme in use at the farms.