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Nutritional strategies to support intestinal health in poultry


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The rising global human population and the improving general human welfare standards comes with an increasing demand for animal proteins. According to an outlook report by the Organisation for Economic Co-operation and Development (OECD) and the Food and Agriculture Organisation of the United Nations (FAO), the poultry meat production will grow over the next 10 years at around 2.3 percent annually to around 134.5 million tonnes of meat making it the largest meat sector from 2020 onwards.

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Nutritional strategies to support intestinal health in poultry

  1. 1. T he rising global human population and the improving general human welfare standards comes with an increasing demand for animal proteins. According to an outlook report by the Organisation for Economic Co-operation and Development (OECD) and the Food and Agriculture Organisation of the United Nations (FAO), the poultry meat production will grow over the next 10 years at around 2.3 percent annually to around 134.5 million tonnes of meat making it the largest meat sector from 2020 onwards. The major part of this growth will be realised in (sub)tropical regions. Therefore, optimum production performance of birds is crucial under a wide variety of climatic and management conditions. Under all circumstances, good intestinal health is a prerequisite, which is challenged by the worldwide tendency for antibiotic-free poultry production. Moreover, continuous selection for improved growth rate and feed efficiency has a potential negative impact on adaptive immunity, metabolic diseases and heat tolerance. Optimised bird management and nutrition can help to safeguard intestinal health and increase the disease resilience of birds. This article reviews several nutritional strategies including application of phytogenic feed additives to support intestinal health in poultry. Intestinal disorders in poultry and their economic impact Poultry has to face many intestinal health threats. Intestinal health problems can be of nutritional, managerial or pathogenic origin. An overfeeding of protein, or minerals (calcium, sodium, potassium) leads to diuresis (excessive urination), characterised by excessive clear fluids in droppings, resulting in wet litter. High levels of anti-nutritional factors like phytic acid, trypsin inhibitors, mycotoxins or some non-starch polysaccharides (NSPs) increase the loss of endogenous fluid, due to impaired intestinal barrier function, so-called physiological diarrhoea. Last but not least, an imbalance in intestinal microbiota (bacteria, protozoa and viruses) can impair intestinal health. Such an imbalance can be initiated by the aforementioned nutritional factors. Coccidiosis remains one of the most universal and major concerns in meat producing poultry and is the most prevalent disease affecting the industry. Williams (1999) estimated that 81 Nutritional strategies to support intestinal health in poultry Table 1. Effects of nutritional strategies on the intestinal disease challenges in broiler chickens (Van der Klis, 2014) Measure Effect increased particle size improved gizzard function and intestinal (anti)peristalsis changing energy delivering nutrients (carbohydrates for fat) better energy absorption, fat digestion being more readily affected in case of intestinal disorders change fatty acid composition (medium chain fatty acids) (increased level of unsaturated fatty acids) MCFA with antibacterial effects unsaturated fatty acids are less dependent on emulsification reduce (fermentable) protein content, maintaining amino acid supply reduce proteolytic bacteria and their fermentation products reduce C. perfringens counts increased dietary inert fibre level improve gizzard function and intestinal (anti)peristalsis improved amylase secretion improved bile acid secretion by Leopold Jungbauer & Jan Dirk van der Klis, Delacon Biotechnik GmbH, Steyregg, Austria 58 | July 2016 - Milling and Grain F
  2. 2. percent of production losses in broilers was due to direct effects of coccidiosis on mortality, weight gain and feed conversion and 18 percent due to the costs of prophylaxis and therapy. Nowadays, global annual financial losses due to coccidiosis are estimated to be 300 million USD. Hafez (2011) reviewed the prevalence of enteric diseases of poultry, with special focus on Clostridium perfringens. He indicated that its prevalence was drastically increased after the EU ban on AGPs, resulting in reduced animal performance, increased mortality rates and increased medication costs. Skinner et al. (2010) estimated that subclinical necrotic enteritis results in a loss to producers ranging from 450 – 750 USD per 10,000 birds. It is clear that a good understanding of these intestinal disorders is needed to be able to develop effective nutritional intervention strategies and feed additives to reduce intestinal disorders in poultry or alleviate its consequences. The impact of nutrition on intestinal health As indicated before, intestinal health issues can have different causes that need to be understood. Intestinal problems that have a nutritional base can be prevented by using well-balanced diets with good quality raw materials, although these are not always readily available. Correct estimates of the nutritional value of feedstuffs and a focus on e.g. reduction of fermentable substrates, proper thermal processing of feedstuffs to eliminate anti-nutritional factors and control for mycotoxins are crucial to minimise intestinal health challenges. It is well-accepted that using too high dietary crude protein levels can increase growth of proteolytic bacteria like Clostridium perfringens. Recently, Veldkamp at al. (2016) have shown that reducing dietary electrolyte balance (dEB) significantly reduced wet litter incidence in turkeys and subsequently improved paw quality. In their study, soybean meal was exchanged by vegetable protein sources with lower potassium contents to reduce dEB. This approach however, can result in an increase in feed costs. Fermentable substrates can also be reduced by the use of Table 2. Effects of some feed additives on intestinal health in poultry (Dhama et al. 2014) Feed additive Effect Probiotic Inhibits growth of disease causing organisms Prevents digestive upsets and diarrhoea caused by bacteria Creates balance in gut microbial population Prebiotic Positive effects on host by stimulating growth and activity of beneficial bacteria Organic acids Ability to reduce pathogenic and spoilage organisms by lowering gut pH Antimicrobial peptides Exogenous enzymes Clay minerals Phytogenics Components of the innate immune system and possess antibacterial and immune-modulatory properties Kill a broad range of microbes including bacteria, fungi and viruses Reduce anti-nutritional factors and degrade non- starch polysaccharides Degrade phytate and increase availability of minerals Bind and immobilisation of toxic material (mycotoxins) in the GI tract Improve nutrient digestibility, especially crude protein with focus on intestinal health Reduce oxidative stress & fatty acids oxidation and improve barrier functions in the GI tract Exert antibacterial effects at high dosages Inhibit quorum sensing and reduce toxin production at low dosages ANDRITZ Feed & Biofuel A/S Europe, Asia, and South America: USA and Canada: Your global technology process supplier for the animal feed industry ANDRITZ is one of the world’s leading suppliers of techno­ logies, systems, and services relating to advanced industri­ al equipment for the animal feed industry. With an in-depth knowledge of each key process, we can supply a compatible and homogeneous solution from raw material intake to finished feed bagging. Milling and Grain - July 2016 | 59 F
  3. 3. exogenous enzymes to degrade fibre fractions and/or make fibre-encapsulated nutrients available to the host animal. Carbohydrases such as xylanases have a significant impact on the breakdown of insoluble fibre fractions in both corn- and wheat- based diets. Thereby, xylanases reduces digesta viscosity but also generate arabino-xylo-oligosaccharides, which act as prebiotics, selectively stimulating the growth of beneficial bacteria. These beneficial bacteria can produce short chain fatty acids (SCFA) in the intestine by fermentation, which in turn can be utilised as an energy source by the animal and result stimulating the growth of strictly anaerobic bacterial species. Eckhaut et al. (2008) have shown that the addition of xylanase reduces Salmonella in birds` caeca, cloaca and spleen, possibly mediated by a specific effect of butyric acid on invasion gene expression. Some nutritional interventions that alleviate the consequences of intestinal disease challenges in broilers have been summarised (Table 1). These nutritional interventions (Table 1) might exert direct antibacterial effects in the intestine (e.g. short and medium chain fatty acids), improve the function of the gizzard and (anti)peristalsis of the gastro-intestinal tract reducing luminal pH, decrease coccidiosis incidence and/or consequences, and/ or reduce supply of substrate to the bacteria by improving nutrient digestibility values. Moreover, physical form of cereal components of feed may affect the morphological and physiological characteristics of the intestinal tract (Brunsgaard, 1998; Engberg et al., 2004). Branton et al. (1987) reported that using wheat ground with a roller mill (coarse ground) compared to a hammer mill (fine ground) reduced necrotic enteritis and coccidiosis related mortality from 29 percent to 18 percent, respectively. Nutritional interventions can be designed to improve the supply of nutrients to the host animal, preventing intestinal challenges or improving the bird’s resilience aiming to reduce the adverse effects of infections on production performance. Feed additives to support intestinal health Recently, an extensive review on the types of growth promoters and feed additives was published by Dhama et al. (2014). Apart from feed antibiotics they dealt with probiotics, prebiotics, organic acids, antimicrobial peptides, exogenous enzymes, clay minerals, essential oils and herbs as feed additives that control intestinal health. Some of the effects of feed additives on intestinal health are summarised in Table 2 Several studies with phytogenic feed additives indicated positive effects on the intestinal morphology, reporting increased villus/crypt ratios after feeding a phytogenic feed additive based on thymol and anethole (Amad et al., 2013), or increased intestinal integrity as was concluded from the effect on transepithelial electrical resistance of duodenal mucosa of broiler fed diets supplemented with thyme essential oils (Placha et al., 2014). Moreover, pungent substances like black pepper, chili and garlic improve intestinal blood flow (Kochhar, 1999), which might reduce the adverse impact of ischemia of the gastro-intestinal tract on intestinal integrity (Niewold et al., 2004). Wallace et al. (2010) tabulated an overview of plant extracts with anticoccidial activity, antibacterial activity against E. coli and C. perfringens, and/or alleviate their effects on poultry. In many cases essential oils were shown not only to reduce weight loss and to improve feed efficiency during a coccidiosis infection, but also reduce oocysts shedding (e.g. for oregano (carvacrol and thymol), artemesia (1.8-cineole and camphor)). Lillehoj (2014) presented data from her lab on the effects of phytogenics on coccidiosis in birds, not only via improved cell- mediated immunity, but also reducing viability of the Eimeria parasites. Finally, combinations of essential oils with medium chain fatty acids have been shown to have synergistic effects. To evaluate the efficiency of such combinations compared to AGP Delacon conducted two necrotic enteritis challenge trials. A summary of these two trials (Figure 1) show that independent of duration of application this combination product improved feed conversion ratio (FCR) and body weight (BW) on day 49. Compared to the positive control including an AGP, no differences in body weight gain were observed when this product was applied, which shows that this combination is an additional tool in drug-free broiler production. Conclusion Good intestinal health is crucial for a successful poultry production. Although farm management is a main factor to control intestinal health, it can be supported by nutritional interventions and the right selection of feed additives. Figure 1. Effects of the duration of supply (day 0-21 or day 0-28) of Biostrong 510 in combination with a mixture of medium chain fatty acids (marketed as Biostrong Forte, dosed 750 mg/kg) as a feed additive to broiler chickens (average of two trials using a clostridial challenge model). 60 | July 2016 - Milling and Grain F