Necrotic enteritis is an infectious, intestinal disease found in broiler chicken flocks. It is caused by bacteria found in dirt, soil, feces and, to some extent, in the intestinal tracts of healthy chickens. Due to the fact that the disease can spread quickly, significant financial loss may occur from an outbreak amongst broiler flocks.
The bacteria responsible for causing this type of broiler disease is called clostridium perfringens. This is an anaerobic bacteria, meaning that it does not require oxygen to survive. The bacteria must mutate into a toxic form to cause enteritis. One of the complexities of the disease is that it can be caused by a number of different types of the clostridium perfringens bacteria.
At first, the presence of necrotic enteritis may not be obvious. Early symptoms of the disease include diarrhea and lethargy. As it progresses, birds may exhibit depression, damaged feathers, reduction in the frequency of feedings, or stop eating all together. They may stop growing due to poor absorption of food by the damaged intestines. Ultimately, birds will die from the infection.
Analysis of the intestinal tract of an infected bird will reveal severe swelling, distention from gas, and lesions. A dark brown, pungent fluid will be present in the small intestine. In its acute form, death can occur in days. In other forms, decline may take over a month, making these forms far more dangerous to the flock. By the time the infection has been identified, many birds will have contracted it, and the financial implications of loss can be significant.
There are a number of factors that can increase the likelihood that a bird will contract necrotic enteritis. One of the most common causes is the composition of the bird's diet. Feed that is composed mainly of cereal grains or animal by-products such as fish meal is more likely to lead to outbreaks than vegetarian feed. Cereal grains, including barley and rye, are high in fiber that broiler flocks cannot digest, making the intestinal environment more susceptible to bacterial growth.
Since necrotic enteritis outbreaks are so costly to the agricultural industry, avoiding them is very important. Many broiler flocks are routinely fed antibiotics with their feed, while the feed itself is more carefully selected to reduce the amount of animal by-products and indigestible grains. Strict hygiene procedures are enforced in broiler flock housing areas to prevent the entry and spread of infection. Housing temperature is also monitored, as warm, moist conditions can assist the proliferation of bacteria.