ABSTRACT
The efficacy of the anticoccidial drugs amprolium, clopidol, diclazuril, monensin, monensin + nicarbazin, narasin, narasin + nicarbazin, and salinomycin against field isolates of Eimeria acervulina obtained from a commercial broiler enterprise before and after immunization with a coccidiosis vaccine was investigated. Evaluated by weight gain, feed conversion, and lesion score following challenge, the isolate obtained before vaccination was resistant to all the drugs tested. By contrast, after vaccination the isolate was sensitive to all drugs evaluated by weight gain, and to most drugs judged by feed conversion and lesion score. It is concluded that vaccination had resulted in the restoration of sensitivity to these drugs.
Subject(s)
Antiprotozoal Agents/pharmacology , Chickens , Coccidiosis/veterinary , Eimeria/drug effects , Poultry Diseases/prevention & control , Protozoan Vaccines/immunology , Animals , Coccidiosis/parasitology , Coccidiosis/prevention & control , Drug Resistance , Male , Poultry Diseases/drug therapy , Poultry Diseases/parasitologyABSTRACT
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 40â ppm nicarbazin or 40â 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 40â ppm nicarbazin + 40â ppm monensin provided complete control of infection judged by greater DWG and DFI, and lower FCR. Monensin at a concentration of 40â ppm was ineffective in preventing lesions caused by all three species. Nicarbazin at a concentration of 40â ppm was unable to suppress lesions of E. acervulina and E. maxima but was able to suppress lesions caused by E. tenella. Nicarbazin 40â ppm + monensin 40â 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.