Necrotic enteritis is a severe bacterial intestinal disease that primarily affects chickens. Characterized by damage to the gut lining, it is a major concern in poultry farming worldwide. It can lead to significant economic losses for producers due to its rapid onset and impact on bird health.
Understanding Necrotic Enteritis
The disease is caused by Clostridium perfringens, specifically types A and C. It is commonly found in the environment, including soil, dust, feces, and feed, and is also a normal inhabitant of a healthy chicken’s intestines. Under certain conditions, Clostridium perfringens can rapidly multiply and produce toxins, such as NetB toxin, which damage the intestinal lining. This leads to necrosis (tissue death) and inflammation in the small intestine.
Identifying Necrotic Enteritis in Your Flock
Recognizing necrotic enteritis can be challenging because clinical signs appear suddenly, leading to rapid deaths. Affected chickens may show depression, ruffled feathers, reluctance to move, and decreased feed intake. Diarrhea can also be observed, often appearing dark, bloody, or foamy. A sudden increase in flock mortality is a strong indicator, with death rates potentially reaching 50%.
Upon post-mortem examination, characteristic lesions are found primarily in the small intestine (jejunum and ileum). Intestines may appear ballooned, distended, and friable, containing foul-smelling, brown fluid. The intestinal lining often has a tan to yellow pseudomembrane, progressing to a “Turkish towel” appearance due to mucosal damage.
Factors That Increase Risk
Several factors can trigger necrotic enteritis outbreaks, even when Clostridium perfringens is present in the gut. Dietary factors play a significant role, with high protein diets, especially those rich in animal by-products like fishmeal, increasing susceptibility. Grains like wheat, barley, oats, and rye, high in non-starch polysaccharides, also contribute by increasing digesta viscosity and providing substrates for bacterial growth. Sudden changes in feed composition can also disrupt the intestinal microflora, creating an environment conducive to Clostridium perfringens proliferation.
Management stressors also heighten risk. Overcrowding, poor litter quality, inadequate ventilation, and sudden temperature fluctuations can suppress the immune system and alter the intestinal environment. Concurrent diseases, particularly coccidiosis, are strongly associated with necrotic enteritis outbreaks. Coccidial infections, particularly from Eimeria maxima or Eimeria acervulina, damage the intestinal mucosa, providing a favorable environment and nutrients for Clostridium perfringens to proliferate. Other conditions that damage the intestinal mucosa, such as mycotoxicosis, can also increase susceptibility.
Strategies for Control and Prevention
Controlling an active outbreak of necrotic enteritis involves antibiotics under veterinary guidance. Bacitracin, penicillin, and lincomycin are commonly used in drinking water for 5 to 7 days. While antibiotics can be effective in reducing mortality and Clostridium perfringens counts, their use is increasingly restricted in many poultry production systems.
Prevention focuses on maintaining a healthy gut environment and minimizing risk factors. Feed management is a primary strategy. Using highly digestible diets and avoiding sudden feed changes helps maintain gut integrity. Incorporating feed additives like probiotics, prebiotics, organic acids, essential oils, and enzymes promotes beneficial gut bacteria and inhibits Clostridium perfringens growth. Probiotics like Bacillus subtilis and Lactobacillus species have shown promise in improving bird performance and reducing bacterial colonization.
Maintaining dry, clean litter is important, as wet litter creates a favorable environment for Clostridium perfringens sporulation. Strict biosecurity measures, including thorough cleaning and disinfection between flocks, proper ventilation, and high water quality, reduce overall microbial load. Given the strong link between coccidiosis and necrotic enteritis, effective coccidiosis control programs are important. This involves anticoccidial drugs or vaccination strategies, which help reduce intestinal damage Clostridium perfringens exploits.