"More attention to the efficacy of disinfectants and litter treatments against Clostridium perfringens will become important factors in controlling NE."
DR. STEVE DAVIS

Necrotic enteritis (NE) is the same disease whether it has an acute or subclinical presentation. Measures to prevent NE, therefore, are similar for both forms of the disease, though the specifics may vary depending on the type of broiler production system in place.

One of the first steps that can be taken to control Necrotic Enteritis is sound cleaning and disinfection of the environment between flocks to decrease the bacterial load in the broiler environment, especially in facilities with a history of NE, says Dr. Steve Davis, president and chief executive officer of Colorado Quality Research, Wellington, Colorado.

"More attention to the efficacy of disinfectants and litter treatments against Clostridium perfringens will become important factors in controlling NE," he says.

Litter moisture should not be too high or low. Oat or rice hull may increase the risk for NE because it is less absorptive,he says.

Dr. Scott Gustin, director of veterinary services for North America and Asia at Arkansas-based Cobb Vantress, notes that some of his colleagues would disagree, but "I have found that reusing litter, if possible, helps stabilize the environmental and coccidial make-up of the house in organic operations that continually struggle with NE."

Dietary influences

Gustin and Davis both emphasize that diet can influence the development of NE. Grains that contain a lot of indigestible soluble fiber, such as wheat, barley, oats and rye, have been linked to intestinal disease in poultry. The use of some feed ingredients associated with NE, Gustin says, is unavoidable due to cost constraints, but producers may be able to at least limit their inclusion rate, especially during times of heavy coccidia cycling when there is more stress on the gut.

Davis’ research has shown that broilers receiving high protein diets are easier to challenge with C. Perfringens, as are broilers receiving higher density diets, which may be because nutrients remain available to the bacteria in the intestine if they are fed at higher levels than the broiler can utilize.

"Integrators raising broilers without feed grade antibiotics maybe able to decrease the incidence of NE by using lower density formuations or concentrating on amino acid fortification and balance overfeeding diets with higher protein levels," he says.

However,dramatic changes in diet,which are linked to development of NE,should be avoided,Davis cautions.

Other factors

Overeating is yet another factor he has linked to NE. "If you slow down feed consumption with measures such as decreased lighting, you can decrease the incidence of NE, which is the opposite of what most people think," Davis says.

Cooler temperatures that chill birds and increase feed consumption are linked to NE mortality, he continues. "It appears that increasing the environmental temperature also decreases feed intake in a broiler flock breaking with NE and will help curtail the severity of an outbreak."

Another factor that can affect the severity of NE is the source of chicks and their quality, Davis says. Flocks with excellent chick quality and uniformity require a greater challenge to create disease, so continued improvements in chick quality should improve control of NE. It could be that different breeds have varying levels of maternal antibody against C. Perfringens, indicating that vaccinating breeders or broilers may be useful in preventing NE.

Gustin agrees that the broiler breed should be considered and that some breeds seem to be more or less likely to develop NE. "As a primary breeder, you try and stay ahead by breeding a bird that can withstand these industry changes. As a producer, you need as many options and tools as possible to keep the feed-conversion ratio and live performance competitive," he says.

Last but not least, bird density is a critical factor in preventing NE,because density affects many of the other variables involved, he says.

Spring 2008

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