Xylanases poultry diets

Another application o f x ylanases is the use of this enzyme in poultry diets. Depression in weight gain and feed conversion efficiency in rye-fed broiler chicks has been associated with intestinal viscosity (24). The efficiency of xylanases in improving the quality of bread has also been demonstrated. The introduction of A. niger var. awamori xylanase into bread dough resulted in an increase in specific bread volume. This is further enhanced when amylase in combination with xylanase is used (25). 

Wheat is the most common cereal used in poultry feed in Australia, Canada and the UK, conventional broiler diets typically containing more than 600 g/kg wheat. Inclusion of xylanase-based enzymes in these diets is now commonplace, to reduce the effects of soluble carbohydrates in wheat on intestinal viscosity and intestinal function. Responses to enzyme supplementation have been shown to depend on age of the bird. More mature birds, because of the enhanced fermentation capacity of the microflora in their intestines, have a greater capacity to deal with soluble carbohydrates in the diet. Replacing maize with wheat reduces the total xanthophyll content of the feed, thus reducing the pigmentation of the broiler skin and egg yolk. Therefore, supplementary sources of xanthophylls may have to be used in broiler and layer diets when wheat is used to replace maize. 

Mulyantini, N.G.A., Choct, M., Li, X. and Lole, U.R. (2005) The effect of xylanase, phytase and lipase supplementation on the performance of broiler chickens fed a diet with a high level of rice bran. In Scott, T.A. (ed.) Proceedings of the 17th Australian Poultry Science Symposium, Sydney. New South Wales, Australia, 7-9 February 2005, pp. 305-307. 

Xylanases are enzymes of great potential for industrial applications. They are mainly used in the pretreatment of Kraft pulp, improving bleachability of pulp while decreasing consumption of chlorine chemicals [5, 6]. These enz3mies are also used as additives to pig and poultry cereal-based diets, to improve nutrient utilization [7], in flour improvement for bakery products [8], in saccharification of agricultural, industrial and municipal wastes [9], and in juice and wine clarification [1]. 

Pentosans present in wheat and rye diets are often poorly metabolized. Especially arabinoxylans negatively influence the digestion and absorption of nutrients in the foregut of animals. When a xylanase (EC 3.2.1.8) treated arabinoxylan fraction was used, the nutritional parameters were similar to those when an arabinose and xylan monomeric mixture was used, indicating that xylanases are a valuable feed additive. Especially sought are enzymes with endo-l,4-P-xylanase activity that are stable in the digestive tract of poultry (Mondou et al. 1986). 

CBMs anchor ceUulases and hemicellulases to their target substrates, therefore eliciting efficient hydrolysis of recalcitrant polysaccharides. Recombinant derivatives of a xylanase from C. thermocellim, containing a CBM6, were used to supplement poultry cereal-based diets. The data obtained showed that birds fed on a wheat-based diet supplemented with CBM-xylanase display an increased final body weight, when compared with birds receiving the xylanase catalytic module only [163]. 

Fontes, CM Ponte, PI Reis, TC Soares, MC Gama, LT Dias, FM et al. A family 6 carbohydrate-binding module potentiates the efficiency of a recombinant xylanase used to supplement cereal-based diets for poultry. Br Poult Sci., 2004, 45(5), 648-56. 

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