What is Necrotic Enteritis in Poultry and Why is it Important for the Poultry Industry?
Necrotic Enteritis (NE), also known as necrotic enteritis, is a common and very costly bacterial disease in poultry. Scientifically, these two terms refer to the same condition. They are, in fact, different translations of the single English term “Necrotic Enteritis.”
- Necrotic: Meaning necrosis, or tissue death.
- Enteritis: Meaning inflammation of the intestine.
Therefore, both terms refer to the same specific disease: intestinal inflammation accompanied by tissue death.
This disease is caused by the bacterium Clostridium perfringens and is recognized as a major challenge in the poultry industry worldwide due to its destructive effects on the health, growth, and productivity of chickens.
The disease is most common in young broiler chickens (2 to 6 weeks old) but can also affect laying hens, particularly during their peak production period. The primary cause is the overgrowth of Clostridium perfringens in the small intestine. This bacterium, which is naturally part of the gut flora of healthy poultry, produces potent toxins like alpha and beta toxins under specific conditions, leading to the destruction and death of the intestinal wall tissue (necrosis).
The Importance of Necrotic Enteritis in the Poultry Industry:
- Heavy Economic Losses: Necrotic enteritis causes billions of dollars in losses to the poultry industry annually. These losses are due to both sudden, high mortality in the acute form of the disease and the hidden, gradual reduction in productivity in the subclinical form.
- Two Forms of the Disease:
- Clinical (Acute) Form: This form is characterized by obvious symptoms such as severe lethargy, dark or bloody diarrhea, and a sudden, significant increase in mortality (sometimes up to 50%). The bird is often severely dehydrated in this state.
- Subclinical (Hidden) Form: This form, without apparent symptoms, chronically damages the intestinal wall. The result is a reduced ability for the bird to absorb nutrients, which directly leads to poor weight gain, inadequate growth, and an increased feed conversion ratio (FCR). This reduction in productivity severely impacts profitability.
- Resurgence of the Disease: With the global trend toward reducing or eliminating growth-promoting antibiotics in poultry feed (due to antibiotic resistance and consumer demand), this disease has resurged as a serious problem. This has doubled the importance of controlling and preventing necrotic enteritis and has pushed the industry toward alternative solutions.
- Dependency on Other Diseases and Factors: This disease rarely occurs in isolation and is often linked to predisposing factors such as coccidiosis, mycotoxin poisoning, and a weakened immune system from viral diseases (like Gumboro). Therefore, managing necrotic enteritis requires attention to the overall health of the flock and its environment.
Symptoms and Diagnosis of Necrotic Enteritis in Poultry
Prompt diagnosis of Necrotic Enteritis (NE) is vital for disease control and minimizing economic losses. This disease poses a major challenge for poultry farmers, not only due to high mortality in its acute form but also because of the hidden, long-term damage caused by its subclinical state. The symptoms of necrotic enteritis appear in two main forms—clinical (obvious) and subclinical (hidden)—each with its own specific signs. Below, we’ll examine these symptoms and diagnostic methods in detail so that farmers can quickly and confidently identify the disease in their flock.
Symptoms of necrotic enteritis vary based on the disease’s severity, which can manifest as either acute and sudden or hidden and chronic.
Clinical (Acute) Form
This form of the disease is marked by a sudden onset of severe mortality. Symptoms are often short-lived and may not be noticed before the bird’s death. These signs include:
- Sudden Increase in Daily Mortality: This is the most common sign, sometimes reaching up to 50% in some cases.
- Lethargy, Depression, and Ruffled Feathers: Affected birds become lethargic, lose their appetite, isolate themselves, and their feathers appear ruffled and dirty.
- Watery Diarrhea: Feces are watery, foamy, and often orange or bloody, leading to wet litter.
- Severe Dehydration: In deceased birds, severe dehydration is evident, with the skin clinging tightly to the muscles.
Related Article: Diagnosing Diseases from Chicken Droppings
Subclinical (Hidden) Form
This form progresses gradually without acute symptoms and is difficult to identify, yet it causes greater economic losses. Its signs primarily affect the poultry’s productive performance and include:
- Reduced Growth and Weight Gain: Due to chronic intestinal damage, affected birds cannot absorb nutrients properly, and their growth is stunted.
- Increased Feed Conversion Ratio (FCR): The poultry requires more feed to reach its target weight, which increases production costs.
- Sporadic Mortality: Deaths occur intermittently throughout the rearing period and are often mistaken for other causes.
Related Article: Examining the Reasons for Poor Chicken Weight Gain
A definitive diagnosis of necrotic enteritis, however, is based on a combination of symptoms, necropsy findings, and laboratory results. The best way to confirm the diagnosis is by performing a necropsy on dead or sick poultry. In this case, the main lesions are found in the small intestine (especially the jejunum and ileum):
- Intestinal Swelling and Fragility: The intestine is swollen, often filled with gas and is fragile, containing a foul-smelling, brownish fluid. The intestinal wall may have a dark red and severely inflamed appearance.
- Necrosis and Tissue Damage: The intestinal mucosa is covered with a yellowish, grayish, or greenish pseudomembrane, which indicates necrosis (tissue death). This ‘blanket-like’ membrane is composed of dead tissue and sometimes has the appearance of ‘tree bark.’ The necrotic mucosa is often visible on the intestinal wall.
- Liver Lesions and Hemorrhage: Necropsy may also reveal severe liver congestion, causing it to become dark or black. In cases where necrotic enteritis is accompanied by coccidiosis, pinpoint hemorrhages are observed on the intestinal wall, and the intestinal contents are bloody and filled with gas.
Finally, culturing the bacteria from the intestinal contents to identify Clostridium perfringens can confirm the diagnosis
Related Article: Strategies for Improving Chicken Gut Health
Predisposing Factors for Necrotic Enteritis in Poultry
Necrotic enteritis (NE) rarely occurs spontaneously; instead, it results from a chain of factors that disrupt the delicate balance of the chicken’s gut, creating a favorable environment for the overgrowth of Clostridium perfringens. This disease often develops as a secondary condition following primary damage to the intestine. The most important factors contributing to necrotic enteritis include:
Intestinal Diseases
Coccidiosis is the most significant and common predisposing factor for necrotic enteritis. This parasitic disease damages the intestinal lining, causing bleeding and providing plasma proteins that serve as a rich food source for C. perfringens. Other intestinal damage from parasites like Ascarids or viruses can also play this role.
Nutritional Factors
The bird’s diet is critical for gut health. Diets with high levels of poorly digestible animal proteins (such as fishmeal) create an ideal substrate for C. perfringens to thrive. Furthermore, grains like wheat, barley, and rye, which contain high amounts of non-digestible fiber, increase the viscosity of feed in the intestine, making digestion difficult. The presence of mycotoxins (fungal toxins) in feed can also damage the intestinal wall, making it susceptible to bacterial growth.
Weakened Immune System
Any factor that suppresses the bird’s immune system increases the risk of necrotic enteritis. Viral diseases like Gumboro (IBD), Marek’s disease (MD), and Chicken Infectious Anemia (CIA) are among the most important immunosuppressive agents.
Poor Management Practices
Weak farm management is another key predisposing factor. Damp and dirty litter provides an ideal environment for the growth of bacteria and parasites (including coccidia). Poor poultry farm ventilation leads to increased moisture and ammonia levels in the house, disrupting the gut’s balance. Additionally, high stocking density, sudden changes in feed, and stress from temperature, transportation, or poultry vaccination can lead to disease outbreaks in the flock. By properly managing these factors and focusing on prevention, the spread of necrotic enteritis can be effectively controlled.
Related Article: Poultry Farming Guide: FAQs for Farmers with Complete Answers
Comparing Chicken Necrotic Enteritis with Sudden Death Syndrome, Paralysis, and Avian Influenza
The symptoms of Necrotic Enteritis (NE), particularly in its acute form, can be mistaken for other diseases that cause sudden mortality. In particular, this disease is often confused with coccidiosis, which is its most important predisposing factor; we have discussed the differences between these two diseases in detail in our dedicated article on coccidiosis. Therefore, for an accurate differential diagnosis from other diseases and to adopt the correct treatment approach, we will now examine its differences with several other important diseases.
- Comparison with Sudden Death Syndrome (SDS): One of the main similarities between necrotic enteritis and Sudden Death Syndrome (SDS) is the sudden death of chickens. In both cases, a bird may be found dead on the litter with no prior signs of illness. However, with necrotic enteritis, mortality is usually accompanied by symptoms such as lethargy and dark diarrhea, and the most crucial diagnostic tool is a necropsy, where specific lesions (such as tissue necrosis and a pseudomembrane) are found in the intestine. In contrast, with SDS, no specific lesions are seen in the internal organs, and the intestine is often full and healthy.
- Comparison with Paralysis in Poultry: In severe cases of necrotic enteritis, a bird may become immobile and weak due to intense lethargy and loss of balance, which could be mistaken for paralysis. However, true paralysis in poultry is typically caused by other issues, such as viral infections (like Marek’s disease), nutritional deficiencies (like a lack of vitamins and minerals), or poisonings that affect the nervous or skeletal systems, not the digestive tract.
- Comparison with Avian Influenza: In the highly pathogenic form of avian influenza, like necrotic enteritis, sudden and high mortality rates can occur. However, necrotic enteritis is a bacterial disease that primarily affects the digestive system, and its main symptoms are related to gut issues. In contrast, avian influenza is a highly contagious viral disease that affects the respiratory system. Its symptoms often include swelling of the head, sinusitis, difficulty breathing, and internal hemorrhaging, making its clinical pattern entirely different from necrotic enteritis.
By considering these comparisons, a proper differential diagnosis can be made through a careful examination of clinical signs and necropsy findings.
Treatment of Necrotic Enteritis in Poultry
The treatment of necrotic enteritis typically begins once clinical signs of the disease have appeared in the flock. Due to the rapid progression of the disease and sudden mortality, swift action is essential to prevent its spread. Treatment usually involves antibiotics, but supportive care also plays a critical role.
Main Treatment Approaches
- Antibiotic Therapy: To combat the bacterium Clostridium perfringens, drugs such as bacitracin, penicillin, and amoxicillin are commonly administered through drinking water. Other medications like oxytetracycline dihydrate (OTC) and doxycycline hydrochloride are also effective in some cases. However, the most important point is that the choice of antibiotic should be made in consultation with a veterinarian and based on bacterial sensitivity to achieve the best results.
- Natural Alternatives and Supplements: Alongside drug therapy, using natural alternatives can help improve gut health and aid in disease control. The use of organic acids like formic acid and lactic acid in drinking water or feed helps maintain a balanced gut pH, creating a more favorable environment for beneficial bacteria. Additionally, some herbal extracts have antimicrobial properties that can help reduce the bacterial load of Clostridium.
- Supportive Care: Supportive care plays a key role in reducing mortality and promoting a faster recovery for sick birds. Providing electrolytes in drinking water helps to compensate for dehydration caused by diarrhea. Reducing environmental stress, such as overcrowding, poor ventilation, and temperature fluctuations, significantly helps to strengthen the bird’s immune system and aid in its recovery.
- Management During an Outbreak: When an outbreak of necrotic enteritis occurs, sick or dying birds should be quickly removed from the flock to prevent the spread of infection. This is especially important to prevent cannibalism. Alongside drug treatment, improving the hygiene and environmental conditions of the house helps in more effective disease control.
Prevention of Necrotic Enteritis in poultry: The Best Strategy
Given the widespread economic losses and increasing restrictions on antibiotic use, prevention is the best and most sustainable strategy for combating Necrotic Enteritis. The disease can not only devastate a flock’s profitability with high mortality, but even in its subclinical form, it causes significant financial losses through a gradual decline in performance and increased feed costs. Therefore, an effective and comprehensive prevention strategy focuses on eliminating or reducing predisposing factors, rather than relying on costly and often late treatment after the disease has occurred. This proactive approach ensures overall flock health and minimizes the need for therapeutic drugs.
Proper Nutritional Management
The dietary formulation plays a key role in poultry gut health. To prevent necrotic enteritis, the following points should be considered:
- Type and form of feed (pellet or mash): Using pelleted feed is generally better than mash feed. The heat from the pelleting process reduces the microbial load of the feed and eliminates certain pathogens. Pelleted feed also has better digestibility and reduces the risk of bacterial overgrowth in the gut.
- Reduce indigestible proteins: Avoid diets with high levels of indigestible animal proteins, such as fishmeal.
- Optimal use of grains: Exercise caution when using grains like wheat and barley that contain high levels of indigestible fiber. If necessary, use feed enzymes to improve digestibility.
- Mycotoxin control: Use high-quality feed that is free from fungal toxins (mycotoxins).
Article: Feed Formulation Methods
Antibiotic-Free Prevention Approaches
With the reduction in the use of antibiotics as growth promoters, the use of natural alternatives to maintain gut health has gained increasing importance as a preventive measure against Necrotic Enteritis. These approaches include:
- Probiotics and Prebiotics: Probiotics (beneficial live bacteria) help balance the gut microbiota and prevent the growth of pathogenic bacteria. Prebiotics act as food for these beneficial bacteria, aiding in their growth.
- Organic Acids: The use of organic acids like formic acid and lactic acid in feed or water lowers the pH of the digestive tract, making the environment unsuitable for pathogenic bacteria.
- Herbal Extracts and Essential Oils: Some herbal extracts, such as oregano oil and cinnamon, have strong antibacterial properties that can help control the population of Clostridium perfringens.
- Feed Enzymes: Adding appropriate enzymes to the diet increases the digestibility of nutrients and prevents indigestible material from remaining in the gut, which would otherwise serve as a food source for bacteria.
Article: Probiotics and Prebiotics in Poultry
Controlling Predisposing Factors
Necrotic Enteritis in poultry is often the result of another underlying issue. Therefore, the management of other diseases is vital:
- Coccidiosis Control: Since coccidiosis is the most important predisposing factor, implementing a precise vaccination program or using anticoccidial drugs (coccidiostats) is essential.
- Immune System Health: To prevent diseases like Gumboro and Marek’s, which weaken the immune system, follow the vaccination schedule carefully.
Smart Management and Improved Environmental Conditions
Stressful environmental conditions can disrupt gut balance. For this reason, proper management is very important:
- Smart Poultry Farming: Using smart systems for continuous monitoring of temperature, humidity, ventilation, and ammonia gas levels in the poultry house helps with more precise environmental control. These AI systems in poultry farming allow farmers to identify and resolve stressors before they can harm the flock by collecting data and providing accurate reports.
- Stress Control: Avoid overcrowding the birds in the house. Prevent any other stressors such as sudden changes in temperature (like heat stress), poor ventilation, or rough handling of the birds.
- Litter Management: Keep the litter dry and clean. Damp litter provides a suitable environment for the growth of bacteria and parasites (including coccidia).
- Biosecurity: Adhering to biosecurity principles at the entrance of the house and for equipment is essential to prevent the spread of contamination.
By following these tips and focusing on prevention, the risk of necrotic enteritis in the flock can be significantly reduced, and productive performance can be improved.
Article: Disinfection and Preparation of the Poultry House delves into the specific conditions for preparing the house and quarantining farm staff.
Challenges and Future of Necrotic Enteritis Control
According to research published in 2024 in the journal Animal Nutrition, despite significant advances in feed additives, the disease of necrotic enteritis in poulrty remains a serious problem in many countries.
This research indicates that none of these alternatives are as inexpensive, reliable, or effective as traditional antibiotics. The main reason for this is the difference in product efficacy between laboratory settings and real-world farm conditions. Successful results in the lab are not always replicated in real-world conditions and depend on factors such as the composition of the product’s active ingredients, the type of feed, and environmental conditions.
Given these challenges, research continues on more reliable solutions for sustainable disease control, such as vaccines. Nevertheless, feed additives continue to be used as important tools for improving overall gut health and flock productivity.
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