Koch's postulate in reproduction of broiler coccidiosis by co-infection with eight most common Eimeria spp.: A model for future evaluation of new biologics

Abstract

The purpose of this research is to establish a model of Koch's postulate for reproducing coccidiosis in broilers by co-infection with eight most common Eimeria spp. involved in this economic disease, in an attempt to use this model in future evaluation of new controlling biologics. Four groups of broilers each challenged at a different age (14, 21, 28, and 35 d) with an equivalent number of sporulated oocysts of eight Eimeria spp. had a reduction in their mean weight gain of 10.2% compared to the four parallel control groups of birds that were deprived of the challenge. The mean feed to live body weight conversion ratio increased significantly from 1.5 in the four unchallengedcontrol groups to 3.1 in the four challenged groups (P<0.05). The mean frequency of mortality increased up to 15% in the challenged groups in comparison to 5% in the controls. This higher mortality was associated in most challenged groups with significant increase in the mean lesion scores and mean oocyst count in the intestine compared to those observed in the controls. The benefit of this established model of Koch's postulate for reproducing coccidiosis in broilers, in future search of new controlling biologics, will be presented.