Synergistic effect of a combination of nicarbazin and monensin against coccidiosis in the chicken caused by Eimeria spp

A clinical study was made into the abilities of nicarbazin and monensin and a nicarbazin + monensin combination to control Eimeria acervulina, E. maxima, and E. tenella in chickens. When included in the feed, at concentrations of 40 ppm nicarbazin or 40 ppm monensin, these products showed partial efficacy evaluated by daily weight gain (DWG) but no activity judged by daily feed intake (DFI) or feed conversion ratio (FCR). By contrast, the combination of 40 ppm nicarbazin + 40 ppm monensin provided complete control of infection judged by greater DWG and DFI, and lower FCR. Monensin at a concentration of 40 ppm was ineffective in preventing lesions caused by all three species. Nicarbazin at a concentration of 40 ppm was unable to suppress lesions of E. acervulina and E. maxima but was able to suppress lesions caused by E. tenella. Nicarbazin 40 ppm + monensin 40 ppm suppressed lesions of all three species. RESEARCH HIGHLIGHTS Nicarbazin or monensin at 40 ppm gave only partial control of Eimeria spp. A combination of 40 ppm nicarbazin + 40 ppm monensin controlled DWG, DFI and FCR. Nicarbazin or monensin at 40 ppm did not suppress all Eimeria spp. lesions. Nicarbazin 40 ppm + monensin 40 ppm suppressed lesions of all three species.