Anticoccidial efficacy of semduramicin. 1. Evaluation against field isolates by dose titration in battery tests

Semduramicin (AVIAX), a novel polyether ionophore, was titrated in a series of five battery tests at 20, 25, and 30 ppm in feed to determine the optimum level for use. Twelve-day-old broiler chicks were medicated for 48 h prior to inoculation in each 9-day test. The inocula included monospecific field isolates of Eimeria tenella, Eimeria brunetti, Eimeria necatrix, and Eimeria maxima, and a mixture of these species with Eimeria acervulina and Eimeria mitis. The numbers of oocysts inoculated were selected after titration of each species and the mixture of species. All three concentrations of semduramicin significantly (P < .05) reduced coccidiosis mortality and lesion scores and achieved lower feed:gain ratios and greater weight gains than the infected, unmediated treatments. A concentration of 25 ppm semduramicin was determined to be optimal based on improved lesion control compared with 20 ppm and improved weight gain compared with 30 ppm.