Battery efficacy studies with arprinocid against field strains of Coccidia.

Graded levels of 9-[2-chloro-6-fluorophenyl)methyl]-9H-purin-6-amine (arprinocid) ranging from 30 ppm to 90 ppm in the diet have been tested for anticoccidial efficacy in controlled battery experiments against 20 field isolates of coccidia. These isolates, representing five major species of Eimeria, were collected from various geographic locations and all but one were found to be resistant to one or more of the currently marketed products. Arprinocid prevented mortality, increased weight gains, and reduced or eliminated intestinal lesions and oocyst production. A level of 60 ppm arprinocid provided adequate control of all isolates and no evidence of cross resistance was observed between arprinocid and the marketed products tested. On the basis of these studies, it is concluded that arprinocid at levels of 60 ppm to 70 ppm is effective in controlling coccidiosis in broilers, even that caused by isolates refractory to many of the marketed products.