Engormix/Poultry Industry/Technical articles

The vicious cycle of necrotic enteritis in layers

Published on: 3/20/2014
Author/s : Teresa M. Agulles Teixidó, Plusvet
The vicious cycle of necrotic enteritis in layers - Image 1
Necrotis enteritis has been ranked as one of the most important diseases affecting poultry operations nowadays. Its occurrence is increasing, especially in countries where antibiotic growth promoters have been banned. Very common in broilers, it is also encountered in laying hens, particularly near the beginning of egg laying or during production peak. Cases in pullets have also been described.
Necrotic enteritis is caused by toxins produced by Clostridium perfringens. Clostridium perfringens is a bacterium that grows under anaerobic conditions (absence of oxygen) and produces spores that are highly resistant to environmental conditions and thus they are not eliminated with the high temperatures used in feed production. Spores are commonly found in litter, feed, manure and facilities.
Clostridium perfringens is a normal inhabitant of the gut flora of healthy hens. Under normal conditions, the “beneficial bacteria” in digestive system keep Clostridium population small in number, but there are risky situations in which the its growth is favored:
  • Any kind of stress, including the transport of the hens to the laying farm, feed transitions, as well as weather conditions.
  • Coccidiosis: it’s the best studied interaction. Coccidia stimulate production of mucus in intestine, which favors the proliferation of Clostridium perfringens.
  • Presence of non-starch polysaccharides in feed.
  • Removal of antibiotic growth promoters.
  • Presence of insects, especially flies.
Once bacteria begin to produce toxins, a vicious circle starts: toxins damage enterocytes, which are not able to absorb nutrients properly, thus the presence of undigested feed in the intestine increases, environment becomes more anaerobic and growth of Clostridium is favored. 
Vicious cycle of necrotic enteritis
The vicious cycle of necrotic enteritis in layers - Image 2
Layers affected by necrotic enteritis are weak, depressed, with ruffled feathers and diarrhea. Mortality is increased and egg production is impaired. Birds may be dehydrated with general congestion. Intestinal mucosa of small intestine is thickened, ulcerated and covered with a brown membrane. Areas of severe necrosis can be found. Liver is pale and enlarged.
Antibiotics the treatment of choice for necrotic enteritis, but many of them leave residues in eggs so there is a withdrawal period and eggs can not be sold during this interval. Also, it is often impossible to effectively use antibiotics since the disease progresses very fast and the toxins involved produce irreversible intestinal damage. Thus, it is most often easier to prevent necrotic enteritis rather than treat it.
Products based on plant extracts with microbiocide and prebiotic properties help to restore or maintain gut heath and the balance of intestinal flora, avoiding the proliferation of Clostridium perfringens. Administration should begin before the pullets are transferred to the laying farm and given during the production peak. GrowthPlus© and PlusProtect Digestive© are products of choice.
PlusLay Immuno© contains vitamins and plant extracts that contribute to recover hen’s productivity after digestive problems such as necrotic enteritis.
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