Gastrointestinal diseases are a major concern for the poultry industry. They lead to production losses, higher mortality rates, reduced poultry welfare and an increased risk of contamination of poultry products for human consumption.
One of the most detrimental diseases is necrotic enteritis, caused by overgrowth of Clostridium perfringens, which usually occurs in broilers at 3-4 weeks of age. Autopsy of infected birds shows typical necrosis in the small intestine.
There are 2 forms of necrotic enteritis. First there is the acute form, which is characterized by a sudden increase in mortality. In most cases there are no clinical warning signs and mortality rates can reach 50%. Clinical signs of diseased animals include depression, dehydration, ruffled feathers, loss of appetite and diarrhea.
Conversely, the second form, subclinical necrotic enteritis, often goes undetected and is therefore not treated by manufacturers. This form of pathology accounts for 80% of cases and is the most costly to the industry. Difficult to diagnose, it can result in significant production losses, reduced feed efficiency and negative impact on welfare.
Management of necrotic enteritis
Necrotic enteritis is typically treated with antibiotics, some in rotational program systems. However, the use of antibiotics is being reduced in many regions of the world due to the emergence of antibiotic resistance. Consumer acceptance of products from animals fed with antibiotics is also declining.
To meet the challenge of maintaining broiler performance and limiting the effects of necrotic enteritis without the use of antibiotics, manufacturers are increasingly interested in alternative strategies such as feed additives.
Phytogenic molecules such as eugenol and garlic compounds have been identified with interesting properties. Eugenol is a naturally occurring molecule in cloves that has demonstrated its ability to strengthen the gut’s physical barrier by increasing the thickness of the gut mucus layer and reducing bacterial adhesion in the gut epithelium.
Several poultry studies have also shown that garlic compounds support immunity parameters by limiting inflammatory processes and promoting optimal gut digestive functions, thereby reducing the number of nutrients available for Clostridium perfringens growth.
In a recent study in Virginia, USA, a mixture of eugenol and garlic compounds was compared to bacitracin methylene disalicylate (BMD) and shown to promote broiler performance under necrotic enteritis challenge conditions.
This 42-day trial was conducted on 1,000 Cobb500 broilers divided into 4 groups:
- Negative Control (Neg C)
- Infected Control (Inf C)
- Eugenol and Garlic Compounds (EG; 100 g/t)
- BMD (50g/t).
At 12 days of age, all birds except negative control groups were inoculated via oral gavage with titrated Clostridium perfringens culture to mimic subclinical necrotic enteritis challenge.