The Effect of Feeding Variable Concentrations of Monensin on the Control of Coccidiosis

Chickens were given concentrations of monensin in the feed which increased at weekly intervals (60 to 121 ppm). This resulted in a fairly constant intake of drug (mg/k body weight). Such chickens consumed less drug than those given monensin at 121 ppm. Chickens given variable concentrations of drug in the food were well protected against coccidiosis judged by the parameters of lesion scores and mortality. Total body weight of these chickens was greater and lesion scores at 28 days were lower compared with chickens given constant levels of monensin, but the differences were not significant. These results suggest that adequate control of coccidiosis in broilers could be achieved by administering a relatively low concentration of an anticoccidial 0 to 3 weeks followed by a high concentration.