Dietary calcium and meat and bone meal as potential precursors for the onset of necrotic enteritis

SUMMARY

Necrotic enteritis (NE) is an enteric disease of poultry caused by Clostridium perfringens (C. perfringens). The incidence of NE has increased in several countries as a result of restrictions on the use of in-feed antibiotics. This disease may be triggered by a combination of coccidiosis and the presence of undigested nutrients in the hindgut providing nutrients and high pH that favour the proliferation of pathogens. Meat and bone meal (MBM) inclusion rates above 4% and higher dietary calcium (Ca) inclusion rates above 1.0% may potentially favour the overgrowth of enteric pathogens, including C. perfringens. High levels of elastin, collagen and keratin from MBM are refractory to gastric digestion and may act as nutrient substrates for C. perfringens. Such proteins are metabolised by C. perfringens by putrefactive fermentation, producing trimethylamine and ammonia, that affect gut health and increase the pH of digesta. Digesta pH may become elevated by feeding a diet high in Ca, as this nutrient has a high acid-binding capacity. Calcium interacts with phytic acid, forming mineral-phytate complexes that decrease the activity of exogenous dietary phytase. This reduces digestion and increases the influx of nutrients into the hindgut. Similarly, smaller particle sizes (dgw <75 μm) and high solubility of some Ca sources could increase digesta pH and chelation of Ca by phytic acid and decrease nutrient digestibility. Whether the practice of overfeeding Ca in order to ensure this nutrient is not limiting for bone development may be putting the bird at risk of a NE outbreak is not known. This review discusses the potential for dietary MBM to exacerbate NE in broiler chickens. The impact of Ca level and particle size to affect gut pH and phytase efficacy are discussed, with inferences to alter the onset of NE.

KEYWORDS:

• Dietary calcium
• meat and bone meal
• necrotic enteritis
• undigested protein

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

H. K. Zanu

Holy Kwabla Zanu holds a PhD in poultry nutrition from the University of New England, Australia. He has a M.Sc. in animal nutrition from the Kwame Nkrumah University of Science and Technology, Ghana and a B.Sc. in Agriculture Technology from University for Development Studies, Ghana. He is currently an academic staff in the Department of Animal Science at the University of Education, Winneba in Ghana. He has close to 30 refereed papers and over 30 conference proceedings.

S. K. Kheravii

Sarbast K Kheravii currently holds a PhD in poultry nutrition and the position of Senior Technical Officer at the University of New England, Armidale, Australia. Sarbast manages molecular biology and gut microbiology laboratories at the same university. Sarbast has published over 15 papers and over 30 conference proceedings and his current interest is nutrigenomics and gut health in broiler chickens.

M. R. Bedford

M. R. Bedford oversees the development of enzyme and yeast products for use in ruminant and non-ruminant feeds. Previously Mike has gained experience working in the feed additives industry in research and development teams. Following his PhD in poultry nutrition and biochemistry at University of Guelph in Canada, Mike undertook two post doctorate posts in Canada in Molecular Biology and Poultry Nutrition. Since then, Mike has written or been involved with over 200 publications - including 76 refereed full scientific papers and 92 abstracts of material presented at conferences.

R. A. Swick

R. A Swick currently holds the position of Poultry Research Coordinator at Poultry Hub Australia in Armidale, Australia. Bob has held various positions in industry and academia including Monsanto Company, Novus International, American Soybean Association and University of New England in Australia. Bob has published over 300 technical papers, bulletins, reports and journal articles and holds a patent on a novel grain preservation system. His current interests are animal energetics, protein and amino acid nutrition, gut health and sustainable poultry production.