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.