APPLICATION OF Eimeria MAXIMA TO A CLOSTRIDIUM PERFRINGENS-ASSOCIATED 
NECROTIC ENTERITIS MODEL FOR STUDYING BACTERIAL COMPETITIVE 
EXCLUSION IN POULTRY.


Ralph N. Marshall, Stephen T.Cartman, Roberto M. La Ragione, Jacqueline A. Marshall and Martin J. Woodward. Veterinary Laboratories Agency (Weybridge), Woodham Lane, New Haw, Addlestone, Surrey, KT15 3NB, UK

C. perfringens-associated necrotic enteritis (NE) is an enteric bacterial disease of poultry. It may present as an acute clinical disease, leading to increased mortality, or a sub-clinical disease which impairs feed conversion. Recognised predisposing factors include environmental stress, diet (particularly when high in wheat, barley or fishmeal) and coccidiosis. To test Bacillus subtilis as a competitive exclusion (CE) agent for prophylactic control of NE, we used a recently developed, non-lethal challenged model. Chicks were fed a diet which was high in wheat and fishmeal content to predispose them to C. perfringens infection. Moreover, 2 x 104 Eimeria maxima oocyts were administered to each bird by oral gavage, at four weeks of age. C. perfringens challenge was then administered via the cloaca one week later. NE lesions were observed in all groups by histological examination of tissue samples post mortem. Interestingly, C. perfringens colonisation was reduced in one group of birds receiving B. subtilis. This work demonstrates the value of E. maxima administration in combination with diet content controls, for modelling C. perfringens-associated NE in poultry. Furthermore, our results show that certain strains of B. subtilis may be useful CE agents for prophylactic control of C. perfringens in poultry.