ANTICOCCIDIAL EFFICACY OF SEMDURAMICIN .2. EVALUATION AGAINST FIELD ISOLATES INCLUDING COMPARISONS WITH SALINOMYCIN, MADURAMICIN, AND MONENSIN IN BATTERY TESTS

The efficacy of semduramicin (AVIAX(TM)), a novel polyether ionophore, was profiled in a series of 57 battery tests conducted in the United States and the United Kingdom. The studies employed mixed and monospec ific infections of Eimeria acervulina, Eimeria mivati/Eimeria mitis, E imeria brunetti, Eimeria maxima, Eimeria necatrix, and Eimeria tenella derived from North American and European field isolates. Ten-day-old broiler cockerels in pens of 8 to 10 birds were continuously medicated in feed beginning 24 h before challenge in tests of 6 to 8 days' dura tion. At the use level of 25 ppm, semduramicin effectively controlled mortality, lesions, and weight gain depression that occurred in unmedi cated, infected controls for all species. In comparison with 60 ppm sa linomycin, semduramicin significantly (P < .05) improved weight gain a gainst E. brunetti and E. tenella, lesion control against E. brunetti and E. maxima, and the control of coccidiosis mortality against E. ten ella. Salinomycin was superior (P < .05) to all treatments in maintena nce of weight gain and control of lesions for E. acervulina. Maduramic in at 5 ppm was inferior (P < .05) to semduramicin in control of E. ac ervulina and E. maxima lesions, but was superior (P < .05) to all trea tments in maintenance of weight gain and control of lesions in E. tene lla infections. The data indicate that semduramicin at 25 ppm is well tolerated in broilers and possesses broad spectrum anticoccidial activ ity.