Gut health management in poultry: Update on Natural Growth Promoters
The antibiotic ban in Europe has driven implementation of alternative strategies worldwide in order to prevent proliferation of pathogenic bacteria, hence maintaining health and performance status and optimising digestion in poultry.
Several approaches have been developed to directly affect microbial communities in the digestive tract. The primary strategy is to prevent the gut from pathogenic invasion by preservation of feed with suitable acidifiers, which may in addition, have a positive impact on growth performance.
Moreover, rapid establishment of a beneficial gut microflora can be achieved by supplementation of probiotics, especially in the early stage of life or after antibiotic medication.
Administration of prebiotic carbohydrates and phytogenic feed additives assists in maintaining a healthy gut microflora throughout the growth period. Finally, NSP-degrading enzymes are known to reduce digesta viscosity, thereby improving energy availability, nutrient digestibility and performance.
Under practical conditions, combined strategies are recommended in order to optimise the use of Natural Growth Promoters (NGPs) in poultry nutrition.
Even under good hygienic conditions, feedstuffs contain a certain number of moulds, bacteria and yeasts. Some mould species (such as Aspergillus, Penicillium, Fusarium) are known to produce mycotoxins, which may negatively affect health and growth performance (Leeson et al., 1995). Acidifiers may well be used to avoid microbial deterioration of feed during storage. Moreover, increased growth performance has been observed when acidifiers have been added to feed (Luckstadt et al., 2004; Skinner et al., 1991).
Immediately after birth, the gut of neonate chicks gets colonised by a large number of microorganisms originating from the environment. Age and physiological state of the birds as well as the dietary composition may affect gut microflora, both in quantitative and qualitative terms.
Oral administration of beneficial bacteria (probiotics) assists in rapidly establishing a beneficial gut microflora, which is generally characterised by high levels of lactic acid-producing bacteria.
A comparatively new category of NGPs originating from herbs and spices has been receiving growing attention in the past few years. Phytogenics are extremely inhomogeneous regarding their ingredient composition and levels of active substances.
Phytogenic components such as carvacrol, thymol or cinnamaldehyde have strong antimicrobial, antioxidant and flavouring properties. Moreover, it has been speculated that phytogenics may stimulate secretion of saliva and digestive enzymes (Lee et al., 2004).
Barley, oats, rye, triticale or wheat contain significant amounts of soluble Non-Starch Polysaccharides (NSP). Inclusion of these grains in diets for poultry produces sticky droppings and poor litter quality. Hence, enzymes specifically tailored to decrease gut viscosity (such as ÃŸ-glucanases, xylanases, pectinases, cellulases and others) are recommended in diets for broilers, layers and turkeys.
Supplementation of cereal-based diets with NSP-degrading enzymes which target the soluble NSP fraction results in a decrease in digesta viscosity and water-holding capacity (Danicke, 1999). Consequently, the transit of digesta in the gut is accelerated, which in turn, may stimulate voluntary feed intake.
In conclusion, several feeding strategies may be implemented to assist in promoting health and performance status in poultry production. Most of the effects of Natural Growth Promoters depend on the age of animals as well as on dosages at which these ingredients are included in feed.
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Article made possible through the contribution of Biomin.