The ins and outs of necrotic enteritis, part 2

The gastrointestinal tract of commercial poultry is constantly exposed to a wide variety of potentially harmful factors which can have a detrimental impact on flock health and productivity. Poultry production is becoming ever more challenging. The drive to reduce antibiotic usage has intensified. Maintaining gut health will therefore become increasingly important for farmers when it comes to securing a competitive advantage. The costly intestinal disease, necrotic enteritis (NE), has severe consequences for gut health. Recently, NE has re-emerged as one of the most serious diseases of commercial poultry, prompting producers to consider whether there is more they could be doing to maximize their flock’s productivity.

Even a minor compromise in gut health can be enough to allow the bacteria to multiply and begin to produce harmful toxins. The gut’s structure - particularly the integrity of the lining of the gut – as well as its microflora and its immune system are vital to intestinal health. Factors which can upset the balance of these elements and are associated with the development of NE include dietary factors, immune status and stress, general management and the presence of other diseases such as coccidiosis.1-3 It’s clear that there is no single solution to preventing NE but that maintaining good gut health must be a priority. This requires farmers, nutritionists and veterinarians to collaborate to make sure birds remain disease-free and perform at their best.

Intestinal health from the inside-out
As the gastrointestinal tract is extremely susceptible to dietary composition, it’s logical that this should be high on the list of factors to address when looking to maximize gut health. Ultimately this can help to increase productivity and reduce susceptibility to diseases such as NE.
For many years, the use of antibiotic growth promoters kept NE levels under control but with the phasing out of antimicrobials, focus has shifted to alternative ways to achieve these goals. The opportunities presented by in-feed short chain fatty acids (SCFAs) in this regard are becoming more widely recognized. Supplemental SCFAs have been shown to positively affect a number of the vital structural and functional aspects of gut health, as well as providing an additional source of energy.3-5
Of the SCFAs, butyrate is of primary importance when it comes to gut health with tributyrins being one of the most effective forms of this product available.

Butyrates – a multitude of actions
Supplementation with butyrate in poultry has been shown to have many benefits:
• optimization of the profile of intestinal microbiota and intestinal pH
• direct antimicrobial properties
• support of tissue development and repair
• improved integrity of the cells of the gut lining
• boosting of the gut’s defence systems

These are all key players in preventing a C. perfringens infection from establishing. Improvements in feed conversion rates and weight gain with butyrate supplementation are likely to be a result of improvements in nutrient digestibility and mineral absorption, as well as increases in intestinal surface area and subsequent absorptive capacity of the gut.3,4

The complete picture
As well as using supplements such as butyrate to promote gut health and strengthen the barriers against intestinal disease, avoiding certain dietary components, which are thought to favor C. perfringens’ growth, may also be useful in decreasing NE incidence. These include ingredients such as fish meal, oats, barley, and rye; excess amounts of which are thought to be used by Clostridial bacteria for growth and toxin production.2

Other factors that can impact on gut health and increase the likelihood of NE include stress and concurrent disease. Both of these are likely to impact on the microbial balance and defense systems of the gut.

Environmental factors such as hot or cold temperatures and any changes in feed, litter conditions, stocking density or vaccination programs may be a source of stress and have been shown to cause immunosuppression, predisposing birds to disease.5,6 Maximizing general hygiene and biosecurity can help prevent NE although such procedures will not be effective on their own.
Coccidiosis is one of the most extensively studied predisposing factors for NE. Like C. perfringens, the coccidian protozoa are present everywhere in the surroundings and can proliferate and cause disease if gut health is compromised. Coccidia can damage the gut lining making it easier for a C. perfringens infection to be established.2
Preventative measures which exert positive effects on gut health can have a multitude of benefits in reducing NE incidence and other intestinal diseases as well as generally improving the health and performance of poultry. As the industry faces increasing challenges, these factors become even more important for producers striving to optimize production.

1. Van der Sluis, W. 2000. Clostridial enteritis is an of- ten underestimated problem. World’s Poult. Sci. J. 16:42– 43.
2. Allaart, J. G., van Asten, A. J., & Gröne, A. (2013). Predisposing factors and prevention of Clostridium perfringens-associated enteritis. Comparative immunology, microbiology and infectious diseases, 36(5), 449-464.
3. Besten G., Eunen K., Groen A., Venema K., Rejngoud D., Bakker B., (2013), The role of short-chain fatty acids in the interplay between diet, gut microbiota and host energy metabolism, The Journal of Lipid Research R036012
4. Gilloteau P., Martin L., Eeckhaut V., Ducatelle R., Zabielski R., Van Immerseel F. (2010) From the gut to the peripheral tissue: the multiple effects of butyrate. Nutrition Research Reviews, 23: 366-384
5. McReynolds, J. L., J. A. Byrd, R. C. Anderson, R. W. Moore, T. S. Edrington, K. J. Genovese, T. L. Poole, L. F. Kubena, and D. J. Nisbet. 2004. Evaluation of immuno- supressants and dietary mechanisms in an experimental dis- ease model for necrotic enteritis. Poult. Sci. 83:1948–1952.
6. McDevitt, R. M., J. D. Brooker, T. Acamovic, and N. H. C. Sparks. 2006. Necrotic enteritis: A continuing challenge for the poultry industry. World’s Poult. Sci. J. 62:221–247.

Jose Maria Ros Felip

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