Efficacy and Characteristics of different Methods of Coccidiosis Infection in Broiler Chickens

Problem statement: Different methods of experimental infection of broiler chickens with Eimeria species have been described in the literature. These methods had not been compared and contrasted so as to contribute to the selection of the most appropriate model of coccidiosis in broiler chickens. Identifying such a model was important to speed up the screening of potential coccidiostatics. Approach: In five different experiments with broiler chickens, we used different methods of infection with Eimeria species. In this paper the different methods and the results have been evaluated. Results: Administration through gavage into the crop of relatively low doses of either Eimeria tenella alone, or in combination with Eimeria acervulina and Eimeria maxima, did not influence body-weight gain and feed intake, but did induce intestinal lesions and faecal shedding of oocysts. The administration of an identically high number of sporulated oocysts in the form of a mixture of the three Eimeria species, either through a single dose by gavage or through the litter, produced similar lowering effects on body-weight gain or feed intake, similar degrees of severity of intestinal lesions and similar rates of faecal oocyst shedding. Conclusion: Depending on the variables considered of interest, the present data may indicate the most appropriate model. The model using infection with oocysts through the litter may optimally mimic the field situation in combination with controlled conditions and allowing experimental flexibility and a high number of experimental units within the research facility.