Necrotic enteritis on poultry: what is it, causes, symptoms, prevention

Necrotic Enteritis (NE) stands as a formidable challenge in modern poultry production, a silent yet devastating intestinal disease that significantly impacts flock health and economic viability. While often manifesting acutely with high mortality, the insidious subclinical form, characterized by chronic gut damage and impaired nutrient absorption, poses an even greater threat to profitability. Understanding the intricacies of NE, from its causative agent to predisposing factors and innovative control strategies, is paramount for sustainable poultry farming.

The culprit: Clostridium perfringens

At the heart of Necrotic Enteritis is Clostridium perfringens, a ubiquitous Gram-positive, anaerobic bacterium commonly found in soil, dust, feed, litter, and the gastrointestinal tract of healthy chickens. While a natural inhabitant, specific conditions trigger its unchecked proliferation and toxin production, leading to the characteristic intestinal lesions. Predominantly, C. perfringens types A and G are implicated in poultry NE, producing potent toxins like alpha-toxin and NetB toxin that severely damage the intestinal lining.

The economic burden: a silent drain on profits

The financial impact of NE on the global poultry industry is staggering, estimated to be in the billions of dollars annually. While acute NE can lead to significant mortality rates (ranging from 2% to 50% in severe outbreaks), it is the subclinical form that often inflicts the most substantial economic damage. Birds suffering from subclinical NE exhibit reduced feed intake, poor weight gain, and an increased feed conversion ratio (FCR). This translates directly into higher production costs, as feed constitutes a major portion of broiler production expenses. The chronic damage to the intestinal mucosa compromises nutrient absorption, leading to suboptimal performance and reduced flock uniformity, ultimately eroding farm profitability.

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Predisposing factors

NE is rarely a standalone issue; it often arises from a complex interplay of predisposing factors that disrupt the delicate balance of the intestinal microflora and compromise gut integrity. These factors create an environment conducive to C. perfringens overgrowth:

Coccidiosis

This parasitic disease is the most significant predisposing factor for NE. Eimeria parasites damage the intestinal epithelium, providing a gateway for C. perfringens to adhere and proliferate. The resulting inflammation and increased mucus production also offer a rich nutrient source for the bacteria.

Dietary composition

• High levels of indigestible non-starch polysaccharides (NSPs): grains like wheat, barley, oats, and rye, rich in NSPs, increase digesta viscosity and slow intestinal transit time, creating a favorable environment for C. perfringens growth.
• High dietary protein, especially animal by-products like fishmeal: poorly digested proteins can serve as a substrate for bacterial fermentation, leading to a build-up of ammonia and an altered gut pH, which can favor pathogenic bacteria.
• Changes in feed composition or particle size: abrupt feed changes can disrupt the gut microbiome, and feed with uneven particle sizes can also contribute to digestive issues.

Immunosuppression

Factors that weaken the bird’s immune system, such as viral diseases (e.g., Marek’s disease, Gumboro disease, Chicken Anemia Virus), mycotoxins in feed, or stress, can increase susceptibility to C. perfringens infection.

Environmental and management conditions:

• Wet litter: provides an ideal environment for C. perfringens sporulation and proliferation.
• Overcrowding and high stocking densities: lead to increased stress and can negatively impact gut health.
• Poor sanitation and biosecurity: facilitate the spread of the pathogen.
• Temperature extremes: cause stress, impacting gut function and microbial balance.

Clinical signs and diagnosis: recognizing the threat

Clinical NE is often characterized by a sudden increase in mortality, sometimes with no prior warning signs. Affected birds may appear depressed, lethargic, have ruffled feathers, decreased appetite, and dark, sometimes bloody, diarrhea. Post-mortem examination is crucial for diagnosis, revealing characteristic lesions in the small intestine, particularly the jejunum and ileum. These lesions can include a distended, friable intestine with a foul-smelling, brownish fluid, and a “Turkish towel” appearance of the mucosal lining due to pseudomembranes. Subclinical NE, being less obvious, is often suspected due to poor growth performance and increased FCR in a flock without significant mortality. Diagnosis can be supported by fecal tests to detect C. perfringens toxins, though definitive confirmation often relies on post-mortem findings and histological examination.

Proactive strategies for prevention and control

Effective NE control hinges on a multi-faceted approach, focusing on gut health, management, and strategic interventions. The move away from antibiotic growth promoters (AGPs) has intensified the search for alternative solutions:

Coccidiosis control

A robust coccidiosis prevention program, including anticoccidial vaccines or shuttle programs, is fundamental to reducing intestinal damage that predisposes birds to NE.

Nutritional management:

• Careful selection of feed ingredients to minimize high levels of indigestible NSPs and poorly digestible proteins.
• Use of exogenous enzymes to break down NSPs and improve nutrient digestibility.
• Balanced amino acid profiles and high-quality protein sources.

Gut microbiome modulation:

• Probiotics and Prebiotics: supplementing diets with beneficial bacteria (probiotics) or non-digestible food ingredients that stimulate their growth (prebiotics) can help establish a healthy gut microbiota, competitively excluding C. perfringens.
• Organic acids and botanicals: these can directly inhibit pathogenic bacterial growth, modulate the immune system, and improve gut integrity. Microencapsulation technology is crucial here to ensure active ingredients reach the small intestine where they are most needed.

Environmental and biosecurity practices:

• Maintaining excellent litter quality (dry and crumbly).
• Implementing strict biosecurity measures to prevent the introduction and spread of pathogens.
• Optimizing stocking density, ventilation, and temperature control to minimize stress.
• Prompt and regular removal of dead birds to prevent further exposure.

Driving performance and health with innovative solutions

The fight against Necrotic Enteritis is ongoing, and innovative feed solutions are critical in this battle. For instance, Vetagro’s research has demonstrated the efficacy of a microencapsulated blend of organic acids (citric and sorbic) and botanicals (thymol and vanillin), marketed as AviPlus®, in reducing clinical signs of NE in broilers. This specialized formulation, protected by microencapsulation technology, ensures the active ingredients are slowly released throughout the intestinal tract, promoting microflora modulation and reducing mucosal inflammation. Studies have shown significant improvements in mortality rates, lesion scores, and even body weight in supplemented birds under NE challenge, highlighting its role in improving gut health and overall performance.

Ready to fortify your flock against the silent threat of Necrotic Enteritis? Explore Vetagro’s advanced nutritional solutions designed to enhance gut health and safeguard your poultry’s performance.