Clostridium perfringens is the toxinsecreting bacterium most often associated with the development of necrotic enteritis (NE). But what happens to C. perfringens organisms when birds are grown without the use of anticoccidials and growth promoters? Do the bacteria mutate to genotypes that might not respond to antibiotic-free strategies, such as vaccination against NE?

Results from a Canadian study indicate this is not the case — that organisms that populate organic houses are likely to be similar to those found in conventional houses, and so are the signs of NE disease they cause.

Jessica Brady and colleagues from the University of Manitoba’s Department of Animal Science characterized C. perfringens isolates from a naturally occurring outbreak at an organic farm. They found that in terms of cellular structure, the type of toxin secreted and the disease signs the toxins produced, all isolates were similar to conventional houses. C. perfringens isolates also remained sensitive to standard antibiotics.

“An outbreak is an outbreak, so you’re going to see the same signs,” Brady reported recently at the annual meeting of the American Association of Avian Pathologists.

She said it’s critical for producers to control factors that predispose birds to the development of NE. Those include pre-existing organisms, feed quality, biosecurity, cleaning and disinfection, and the quality of vaccination programs.

Alpha-toxoid vaccines have been shown to be protective against NE and their use may decrease the intensity of NE, but the best approach is a “multi-factorial system” that also includes good feed quality, biosecurity, and cleaning and disinfection, added Brady, whose colleagues in the study were C. Rodriguez-Lecompte, J.D. Hernandez, J.D. House, C. Bennett and W. Guenter.