Necrotic Enteritis in Poultry
What is necrotic enteritis?
Necrotic enteritis (NE) is an intestinal disease that often manifests in commercial broiler flocks worldwide. The disease is characterized by dead tissue/lesions and inflammation of the GI tract. This disease can cause high mortality rates, primarily in young broiler chicks.
How big is the impact of necrotic enteritis on the global poultry industry?
The prevalence of necrotic enteritis worldwide is highly variable and is estimated to be anywhere between 1–40%. As such, its impact on the global poultry industry can vary widely from an economic and welfare standpoint. Flock health and overall performance in the face of necrotic enteritis are also dependent on which type of the disease is present. While clinical necrotic enteritis often causes high morbidity and mortality rates, subclinical forms of necrotic enteritis may be less evident and only tend to affect growth and feed conversion rates. Therefore, subclinical necrotic enteritis may be more common and, as a result, may have a greater impact on the global poultry industry. Globally, it is estimated that necrotic enteritis costs about $0.05 per chicken and about $2 billion in losses per year.
What causes necrotic enteritis?
Necrotic enteritis is an infection and acute enterotoxemia caused by the Gram-positive bacteria Clostridium perfringens Types A and C. C. perfringens is ubiquitous and is a normal inhabitant of the gastrointestinal tract of healthy chickens and turkeys. Clinical necrotic enteritis outbreaks are based on complex interactions between the microorganism and other predisposing factors.
Although the mechanism for C. perfringens virulence is not completely understood, the toxin type is typically the cause of pathogenesis. The incidence of necrotic enteritis increases when there are any changes, whether physical or chemical, that contribute to the colonization of C. perfringens to the gut, where they can degrade mucus, colonize enterocytes, secrete enzymes and induce further damage to the gut wall. Factors that contribute to the rate of bacterial growth with C. perfringens include the diet type, stress levels in birds, previous medical treatments, the rate of feed passage, the presence of mycotoxins, the immune status of the birds and co-infection with other pathogens, such as Eimeria spp. and viruses.
What are some common signs and symptoms of necrotic enteritis?
Clinical signs of necrotic enteritis can vary depending on the presentation of the disease. Sudden, clinical and subclinical forms have all been described; however, subclinical forms tend to occur more frequently and are considered the primary cause of economic losses. Clinical signs of necrotic enteritis can vary, from non-specific symptoms to depressed birds, ruffled feathers, decreased appetite, anorexia, dehydration, lethargy, diarrhea and death. Gross lesions in the gastrointestinal tract can be seen primarily in the jejunum and the ileum; however, they can also be seen, to a lesser extent, in the duodenum and the ceca. The intestines may feel friable, thin, distended and edematous, with visible gas and blood, and may have a yellow, white or green pseudomembranous layer attached to the mucosa (which has been described as having a “Turkish towel” appearance). Cholangiohepatitis and hepatitis have also been reported as a result of C. perfringens gaining access to portal circulation and bile ducts, thereby causing necrosis in the liver and the bile ducts.
Management tips to help prevent and combat necrotic enteritis
Necrotic enteritis can be controlled by reducing the risk factors associated with it. Some tips include:
- Establishing gut integrity and microbiome diversity: While subtherapeutic levels of ionophores and other antibiotics are used to control Clostridium overgrowth and provide some modulation to the gut microbiota, they have increasingly been replaced by alternative natural products. The use of competitive exclusion products provides a suitable alternative to restoring the microbiota in the bird’s gastrointestinal tract. It can also help decrease the incidence of necrotic enteritis and reduce the morbidity and mortality associated with necrotic enteritis.
- Utilizing high-quality feed ingredients: Using high-quality feed ingredients and reducing or removing products from the feed that increase the incidence of necrotic enteritis are recommended.
- Incorporating feed additives: The use of feed additives — such as prebiotics, probiotics, postbiotics, organic acids, enzymes and trace minerals, like zinc and selenium — can also help combat necrotic enteritis.
- Following a well-rounded coccidiosis prevention program: Coccidia play an essential role in the incidence of necrotic enteritis; therefore, a well-rounded coccidia control program is an essential element of reducing necrotic enteritis.
- Implementing good animal husbandry practices — such as the proper biosecurity measures, cleaning and disinfection, pest control, the prompt removal and disposal of deceased birds, maintaining good litter quality, providing regular access to high-quality feed and clean water, and more— are essential components of maintaining overall flock health, as well as reducing other diseases and decreasing the incidence of necrotic enteritis.