Enzymes for the feed industry: past, present and future

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1 Reviews DOI: /WPS Enzymes for the feed industry: past, present and future M. CHOCT Australian Poultry Cooperative Research Centre, University of New England, Armidale, NSW 2351, Australia The commercial application of enzymes as a feed additive has a history of less than 20 years. During this period, the feed enzyme industry came into existence and it has gone through several phases of development. The first phase was the use of enzymes to enhance nutrient digestibility, focusing primarily on removing the anti-nutritive effects of non-starch polysaccharides (NSP), such as arabinoxylans and β-glucans, from broiler diets based on viscous grains like wheat, rye, barley or triticale. During the early 1990s, the scope of enzyme application expanded to consider nutrients other than NSP and benefits other than digestibility enhancement. Phytase is a prime example, where not only was it used to increase the utilisation of phytate P, but also to alleviate environmental burdens by reducing P excretion in the excreta. The industry then started to advocate enzyme addition to poultry diets based on nonviscous grains, such as sorghum and corn. Although such a use is not uncommon in some parts of the world, the industry is still in search for highly efficacious enzymes for non-viscous cereal grains. The next phase is the application of enzymes to noncereal grain components of the diet. These vegetable protein sources are often high in NSP, which are poorly characterised in regard to their molecular structures. Significant progress has been made on characterisation of the NSP in soybean, but the industry has not been able to produce commercially viable products that consistently improve the digestibility of vegetable proteins. The enzyme industry today is constantly searching for new areas of application. Some recent data demonstrate the role of glycanases (charbohydrate degrading enzymes) as an alternative to in-feed antibiotics. It is possible to produce enzymes tailored for (a) the generation of specific low molecular weight carbohydrates in vivo, which, in turn, produce specific health outcomes in birds; (b) de-activation of anti-nutrients other than NSP and phytate, and (c) degradation of non-conventional feed resources to yield ME. The development of enzyme technology needs to go hand in hand with better characterisation of substrate structures, the gut microflora, and the immune system. Keywords: enzymes; NSP; poultry; microflora From a paper first presented at the XXII World s Poultry Congress, 8-13 June 2004, Istanbul, Turkey World s Poultry Science Association 2006 World s Poultry Science Journal, Vol. 62, March 2006 Received for publication August 4, 2004 Accepted for publication October 7,

2 Introduction The move towards the use of diets devoid of ingredients of animal origin will exacerbate the effect of anti-nutrients on bird performance and nutrient excretion in the environment. One of the key technologies that can help address this challenge is the use of appropriate enzymes. The enzyme technology has progressed a great deal over the past twenty years with respect to efficacy and matching activities with their target substrates. For example, β-glucanases and xylanases for degradation of the β-glucans and arabinoxylans in barley, oats, wheat, rye and triticale have proven efficacy in enhancing the nutritive value of these grains for poultry, in particular, for broiler chickens. The inclusion of microbial phytase to improve the utilisation of organic phosphorus is another good example. The benefits of using enzymes in monogastric diets include not only enhanced growth performance and feed conversion, but also fewer environmental problems due to reduced output of excreta. Increased accuracy and flexibility in least-cost feed formulations and improved well being of animals are other possible benefits of using feed enzymes. As more and more knowledge is gathered on the detailed chemical structures and the physiological activities of NSP in various ingredients, highly sophisticated enzymes will be developed to target these polymers in a precise manner. Therefore the use of NSP as energy sources, a more efficient utilization of non-conventional ingredients, such as copra meal, palm kernel cake, sunflower meal and some industrial wastes, and the elimination of specific antinutritive factors, such as protease inhibitors, glucosinolate, alkaloids, saponins and polyphenolics will receive increasing attention from enzyme manufacturers in the future. The enzyme industry is vigorously investigating the production of natural substrates in situ to nurture and/or develop commensal gut microflora which will maintain good bird health and performance. This paper will review the past and present of feed enzymes and will hypothesize the future role of feed enzymes in animal nutrition. The past GLYCANASES The concept of using enzymes in animal feed is not new, but early researchers believed that animals fed high-grain diets lacked the necessary digestive enzymes to degrade the excessive amount of starch and adding amylase to their diet would overcome this deficiency. Indeed, the results appeared to support the hypothesis. In the first ever study on the use of feed enzymes in poultry diet, Clickner and Follwell (1925) used an enzyme product named Protozyme, which was produced from Aspergillus orizae, in a pullet diet and reported improved bird performance. For more than 6 decades following this study, reports on the use of enzymes in poultry diets appeared only sporadically. Hastings (1946) and Fry et al. (1957) used a crude amylase preparation in barley-based chicken diets and obtained significantly improvement in liveweight gain and feed conversion efficiency. It is now well-established that the starch in barley is totally digestible by the amylase secreted by chickens. Therefore the reported improvements with amylase supplementation were probably due to the impurities in the enzymes used, i.e., the crude enzyme preparation contained β-glucanase activity. The β-glucan is a glucose polymer containing a mixture of β1-3 and β1-4 linkages that make its physicochemical properties totally different from cellulose that is a straight-chain glucose polymer with only β1-4 linkages. Barley contains a high level of mixed-linked β-glucan (3-4%) and the pioneering work of Burnett (1966) not only identified β-glucan as the factor responsible for the poor nutritive value of barley but also elucidated the effect of viscosity on nutrient digestion in the gut. 6 World s Poultry Science Journal, Vol. 62, March 2006

3 Thus, β-glucanase supplementation became a practical solution for improving the nutritive value of barley for poultry since 1980s (Hesselman and Åman, 1986; Campbell et al., 1989; Broz and Frigg, 1986; Newman and Newman, 1987). A similar approach was taken to develop enzymes for rye- and wheat-based diets. These cereals contain considerable amounts of soluble arabinoxylans, which behave in the same manner to β-glucans from barley (Fernandez et al., 1973; Antoniou et al., 1981; Fengler and Marquardt, 1988a,b; Choct and Annison, 1990). Therefore, addition of pentosanase (xylanase) to poultry diets based on rye or wheat markedly improved their nutritive value (Pettersson and Åman, 1988;1989; Annison, 1991; Bedford and Classen, 1992). The application of enzymes on a practical scale in the poultry industry was possible due to the recognition that the soluble non-starch polysaccharides (NSP) present in viscous cereals, such as rye, barley, triticale and wheat, impairs nutrient digestion and absorption. The detrimental effects of NSP are associated with their ability to increase digesta viscosity, to interact with the microflora of the gut, and to alter the physiology and morphology of the digestive tract. These effects are dependent on the polymeric nature of the polysaccharides and therefore cleaving of the polymers can largely eliminate their anti-nutritive properties. Enzymatic cleavage is obviously the most practical and costeffective way of breaking down NSP in the gastrointestinal tract of the animal. However, the marked effect of glycanases on the nutritive value of cereal grains, such as wheat, rye and barley, are not due to a complete breakdown of the polymers and subsequent absorption of the released monomers. The current enzymes are not capable of depolymerzing NSP to their simple constituents during the digesta transit time of poultry. PHYTASE The hidden benefits of using glycanases in birds fed viscous cereals include (a) reduction in output of manure containing large amounts of undigested nutrients, and (b) alleviation of problems associated with wet droppings, such as increased percentage of dirty eggs, increased gas production (i.e., ammonia) and increased fly and rodent populations in the shed. However, glycanase supplementation was not the answer to problems associated with phosphorus levels in pig and poultry manure. This led to the development of phytase for use in monogastric animal diets. Phytase increases the digestibility of phytate from around 25% to 50-70% in poultry and its use has been on the increase since banning the use of animal protein sources, such as meat and bone meal, in the EU. It is also understood that phytase can improve the digestibility of other nutrients as well as energy (Ravindran et al., 1999; 2000; Kornegay, 2001). The present GLYCANASES Cereal grains are broadly classified into two major categories, viscous and non-viscous cereals, according to their content of soluble NSP. For example, rye, barley, oats, wheat and triticale contain considerable amounts of soluble NSP and are classified as viscous grains, whereas corn, sorghum, millet and rice contain negligible amounts of soluble NSP and are known as non-viscous cereals. Table 1 shows the NSP content and constituents of selected grains. The significance of this classification rests on the pretext that increased digesta viscosity impairs nutrition digestion and absorption in poultry (Burnett, 1966; Choct and Annison, 1992; Bedford and Classen, 1992; Danicke et al., 1999). But the expansion of the enzyme industry since the 1990s means that enzymes for ingredients other than viscous grains need to be searched. The ingredients include (a) vegetable protein sources which contain World s Poultry Science Journal, Vol. 62, March

4 large amounts of NSP, including soluble NSP; (b) non viscous grains, such as corn, sorghum and millets; (c) by-products of cereals and the food industry, and (d) nonconventional raw materials, such as palm kernel cake, copra meal and sunflower meal. The current development is briefly summarised in the following sections. Enzymes for poultry diets based on non-viscous cereals Although the insoluble NSP have mainly been regarded as a nutrient diluent in the diet, they can also affect digesta transit time and gut motility. Another facet of the role of insoluble NSP in poultry diets that is worthy of reiteration is their ability to act as a physical barrier to digestive enzymes, such as amylase and proteases, thus reducing their efficient digestion of nutrient embedded in the cell wall matrix of grains. Evidence in the literature appears to suggest that enzymes with affinity for insoluble NSP can elicit a positive response in growth performance of broilers (Cowan, 1995; Choct, 1998). This indicates breakdown of cell wall matrix, especially the insoluble components, may facilitate easier access of digestive enzymes to their substrates within the short feed transit time in birds. Wiseman and McNab (1998) also showed that the rate of starch digestion in vitro correlates closely with the AME values of different wheats. It suggests that the accessibility of amylotytic enzymes to starch granules differs depending on the wheat type, and some the of key factor influencing it may relate to the cell wall architecture of the wheat. Bedford (2002) demonstrates that a considerable amount of nutrients such as starch remains encapsulated in the cell walls in the small intestine of chickens and is removed upon xylanase supplementation. Indeed, D Alfonso (2003) reported significant variation in the nutritive value of corn (93 samples examined) for chickens with ileal digestible energy value varying by 2.04MJ/kg DM and starch digestibility ranging from 84% to 90%. This variation was reduced by an enzyme product containing xylanase, protease and amylase. Cowieson (2005) speculated that the ability of enzymes, in particular, glycanases, to enhance the nutritive value of some corn-soy diets is probably mediated through changes in cell wall architecture of the gain, rather than viscosity reduction as it is often the case for viscous grains. Vegetable protein sources Grain legumes are usually included in monogastric diets as protein sources. However, when some grain legumes such as lupins are included in poultry diets as the sole protein source, bird performance suffers due to the high levels of NSP and the oligosaccharides present. Legume NSP are more complex in structure than those in cereals, containing a mixture of colloidal polysaccharides called pectic substances (galactouronans, galactan and arabinans). Neutral polysaccharides such as xyloglucans and galactomannans have also been reported. The Australian sweet lupin, for instance, contains a rhamnogalactouronan with arabinose and galactose side chains, with at least 4-6 different linkages (Cheetham et al., 1993). Figure 1 shows the structure of a pectic polysaccharide isolated from lupins. A detailed analysis of the carbohydrate composition of 6 lupin samples shows that total amount of carbohydrates ranges from 34.1% to 39.3% on dry matter basis, which is composed of % rhamnose, % fucose, % ribose, % arabinose, % xylose, % mannose, 72-75% galactose and % glucose. Starch is present at less than 1%. Undoubtedly, a total depolymerisation of the complex NSP of grain legumes requires extremely complex enzyme activities. Thus, Annison et al. (1996) demonstrated that some commercial enzymes had a significant effect on lupin NSP in vivo. If the NSP in lupins are efficiently utilised as an energy source, their nutritive value for poultry will be increased by 50%. Appreciable improvements can be expected for other vegetable protein sources if effective enzymes are developed to degrade the NSP present in these ingredients. The NSP levels 8 World s Poultry Science Journal, Vol. 62, March 2006

5 and constituents are shown in Table 2. Kocher et al. (2002) added an enzyme product consisting mainly of pectinase to a corn-soy diet and obtained a significantly increase in the ME value of the diet. This improvement in the ME coincided with the digestibility of galactose-rich polysaccharides, most likely the rhamnogalacturonans. However, an effective enzyme to degrade pectic polysaccharides present in commonly used vegetable protein sources for poultry is yet to be developed. Furthermore, under commercial conditions some of the vegetable protein sources, such as lupins, peas and beans are used at small quantities and therefore the characterisation of their substrates for the purpose of producing targeted enzymes is probably not on the priority list for enzyme manufacturers for economic reasons. Substrate structure and enzyme affinity Matching an enzyme activity with a substrate does not guarantee the efficacy of the enzyme in degrading the substrate. Currently most of the glycanases used in the poultry industry target the soluble carbohydrates in an endo-active manner, i.e., cleaving the molecules from the middle to reduce the molecular size with little or no monomeric sugars released (Bhat and Hazlewood, 2001). Substrate specificity depends largely on the source of the enzyme. Choct et al. (2004) reported three xylanases that are of different substrate affinities. A xylanase derived from Thermomyces lanuginosus, significantly increased the soluble NSP content of the small intestinal digesta, but decreased its viscosity, whereas a xylanase derived from Humicola insolens markedly increased both the content of the soluble NSP in the small intestine as well as its digesta viscosity. This clearly demonstrated that the xylanase from T. lanuginosus had affinity for both soluble and insoluble arabinoxylans, e.g., whilst releasing soluble NSP from the insoluble cell wall xylans, it also degraded them into smaller polymers, but that from the H. insolens had affinity for only the insoluble cell wall xylans. The third xylanase used in this study was from Aspergillus aculeatus, which effectively degraded the soluble arabinoxylans, but had no effect on the insoluble fraction. The NSP degradation patterns appear to indicate that enzymes having affinity for both soluble and insoluble NSP will be more efficacious. However, these differences, in general, did not translate into apparent differences in bird performance despite some numerical trends. Some selected data from this study are shown in Tables 3 and 4. The future THE USE OF NSP AS ENERGY SOURCES Large amounts of grain by products, such as wheat bran and rice bran, and nonconventional ingredients, such as palm kernel cake, copra meal and sunflower meal, are available for use in poultry diets in many parts of the world, but these materials are characterised by their very high contents of mostly insoluble NSP. For example, most cereal grains and their by-products contain large amounts of arabinoxylans and cellulose as the main NSP. The structure of both polymers is well characterized and the enzyme technology is available for a complete breakdown of these substrates. Cellulose is a straight chain 1-4 β-glucan and requires a combination of cellobiohydrolase, endoglucanase and β-glucosidase for complete breakdown to glucose. The (1-3), (1-4) - β- glucan of barley and oats can be rapidly broken down to glucose with the combination of endoglucanase and β-glucosidases. Rice bran, for instance, contains approximately 20-25% NSP, half of which is cellulose (Saunders, 1986). Copra meal and palm kernel cake contain high levels of mannans or galactomannans, with a total NSP level reaching 70%. Of particular significance is the increased use of grain for biofuel production, which yields World s Poultry Science Journal, Vol. 62, March

6 the so-called distillers grains. This co-product is further classified into distillers dry grains (DDG), the dried residue of distillers grains, and distillers dry grain with solubles (DDGS), the DDG with syrups added. DDG accounts for approximately 30% of dry grains for ethanol production, and it contains 25-28% protein, 8-9% fat, 5% ash and the remainder is believed to be NSP. This figure agrees well with the 42.1% NDF content reported for DDGS (Spiehs et al., 2002). It is estimated the world produces as much as 60 million tonnes of DDG each year. The nature of the NSP is not known, but it may be deduced that they would be composed mainly of cellulose and arabinoxylans. Currently DDG is used predominantly in cattle feed although in some countries it is also used in swine rations. The potential of using enzymes to DDGS for the release of metabolisable energy for monogastric animals is enormous. However, the current enzymes are not designed to degrade NSP to monomeric sugars within the food transit time of the chicken and pre-treatment is necessary in order to yield a substantial amount of simple sugars. With development of highly sophisticated enzymes and fine-tuning of pre-treatment procedures, all these NSP not only represent a large source of potential energy but also prebiotics with specific functions for poultry. Tailoring enzymes for their secondary effects It is possible that the digestibility of feed components can be tailored to produce end products with specific effects on the gut microflora and the immune system. Austin et al. (1999) reported that a single cloned endo-1-4 xylanase produced much the same range of oligosaccharides from different wheats fed to chickens. This means that a specific range of oligomers can be produced from a given NSP source in situ with a particular enzyme. Some of these carbohydrates may be used to stimulate the development of beneficial microflora in the gut. The gut harbours a highly evolved and complex microbial ecosystem containing a vast number of diverse populations. For example, microbes make up approximately 600 g/kg of the wet weight of poultry excreta. The proper feeding of poultry should therefore consider the provision of correct substrates for the microflora to keep it stable. The consequences of altered rate of nutrient digestion in the gut may be manifested in the number and type of microorganisms present in the gut. Production of xylo-oligosaccharides by the use of xylanases in wheat-based diets could be one way to encourage the development of a healthy gut microflora (Vahjen et al., 1998). Indeed the direct benefit of enzyme supplementation for poultry health has been demonstrated. Thus, Sinlae and Choct (2000) demonstrated that broilers fed a wheat-based diet with xylanase had a negligible number of Clostridium perfringens compared with the control birds. A more detailed study by Bedford and Apajalahti (2001) showed that xylanase supplementation of birds fed wheat-based diets markedly reduced the coliforms, lactic acid bacteria, enterococci and the total bacterial count in the small intestine. Another example is the use of specific carbohydrate entities to boost the immune system or reduce the load of pathogens in the gut. Manno-oligosaccharides have been reported to enhance the immune functions in poultry (Spring et al., 2000). Producing specific mannooligomers from copra meal and palm kernel cake in situ is possible. Deactivation of anti-nutrients in feed In addition to NSP, many feed ingredients contain a number of anti-nutritive factors. These include inhibitors of various digestive enzymes (protease inhibitors, trypsin inhibitors), polyphenolics (lignin and tannins), lectins, alkaloids, saponins and glucosinolate. For example, breakdown of glucosinolate in rapeseed using thioglucosidase has been trialed (Lawrence et al., 1995); Huo et al. (1993) demonstrated that trypsin inhibitors in soybean were completely deactivated by a protease within 80 minutes in vitro. Another exciting area of development will be the use of specific strains of micro- 10 World s Poultry Science Journal, Vol. 62, March 2006

7 organisms that produce a high level of enzymes as feed additives. Cooper et al. (1995) applied such an approach to degrade an anti-nutrient in pasture species, fluoroacetate, which is a significant problem in Africa, Central America and Australia. Under a strictly controlled experimental condition, they used a strain of rumen bacterium Butyrivbrio fibrisolvens which was genetically engineered to produce an enzyme to degrade fluoroacetate. The approach was highly effective. Similar pathways are available to solve many practical problems, however, the debate on, and the public reluctance of, using GMO for such a purpose has stalled rapid development in this area of enzyme application. References ANNISON, G. (1991) Relationship between the levels of soluble non-starch polysaccharides and the apparent metabolizable energy of wheats assayed in broiler chickens. Journal of Agricultural and Food Chemistry 39: ANNISON, G., HUGHES, R.J. and CHOCT, M. (1996) Effects of enzyme on the nutritive value of lupins for poultry. British Poultry Science 37: ANTONIOU, T., MARQUARDT, R.R. and CANSFIELD, E. (1981) Isolation, Partial characterization, and antinutritional activity of a factor (pentosans) in rye grain. Journal of Agricultural and Food Chemistry 28: AUSTIN, S.C., WISEMAN, J. and CHESSON, A. (1999) Influence of non-starch polysaccharide structure on the metabolisable energy of UK wheat fed to poultry. Journal of Cereal Science 29: BEDFORD, M.R. and CLASSEN, H.L. (1992) Reduction of intestinal viscosity through manipulation of dietary rye and pentosanase concentration is effected through changes in the carbohydrate composition of the intestinal aqueous phase and results in improved growth rate and food conversion efficiency of broiler chicks. Journal of Nutrition 122: BEDFORD, M.R. and APAJALAHTI, J. (2002) Microbial interactions in the response to exogenous enzyme utilization. Enzymes in Farm Animal Nutrition, (Bedford, M.R. and Partridge, G.G., eds.), pp CABI Publishing, London. BEDFORD, M.R. (2002) The role of carbohydrases in feedstuff digestion. Poultry Feedstuffs: Supply, composition and nutritive value (McNab, J.M. and Boorman, K.N., eds.), pp , CABI Publishing, London. BHAT, M.K. and HAZLEWOOD, G.P. (2001) Enzymology and other characteristics of cellulases and xylanases. Enzymes in Farm Animal Nutrition, (Bedford, M.R. and Partridge, G.G., eds.), pp CABI Publishing, London. BROZ, J. and FIRGG, M. (1986) Effects of beta-glucanase on the feeding value of broiler diets based on barley or oats. Archiv für Geflügelkunde 50: BURNETT, G.S. (1966) Studies of viscosity as the probable factor involved in the improvement of certain barleys for chickens by enzyme supplementation. British Poultry Science 7: CAMPBELL, G.L., ROSSNAGEL, B.F., CLASSEN, H.L. and THACKER, P.A. (1989) Genotypic and environmental differences in extract viscosity of barley and their relationship to its nutritive value for broiler chickens. Animal Feed Science and Technology 26: CHEETHAM, N.W.H., CHEUNG, P.C.K. and EVANS, A.J. (1993) Structure of the principal non-starch polysaccharide from the cotyledons of Lupinus angustifolius (cultivar Gungurru). Carbohydrate Polymers 22: CHOCT, M. (1998) The effect of different xylanases on carbohydrate digestion and viscosity along the intestinal tract in broilers. Australian Poultry Science Symposium 10: CHOCT, M. and ANNISON, G. (1990) Anti-nutritive activity of wheat pentosans in broiler diets. British Poultry Science 31: CHOCT, M. and ANNISON, G. (1992) Anti-nutritive effect of wheat pentosans in broiler chickens: roles of viscosity and gut microflora. British Poultry Science 33: CHOCT, M., KOCHER, A., WATERS, D.L.E., PETTERSSON, D. and ROSS, G. (2004) A comparison of three xylanases on the nutritive value of two wheats for broiler chickens. British Journal of Nutrition (in press). CLICKER, F.H. and FOLLWELL, E.H. (1925) Application of protozyme by Aspergillus Orizae to poultry feeding. Poultry Science 5: COOPER, C., SCHAFER, D. and GREGG, K. (1995) Use of engineered rumen bacteria to degrade fluoroacetate. Proceedings of the Recent Advances in Animal Nutrition in Australia pp (Rowe, J.B and Nolan, J.V., eds.), University of New England, Armidale, NSW 2351, Australia. COWIESON, A.J. (2005) Factors that affect the nutritional value of maize for broilers. Animal Feed Science and Technology 119: World s Poultry Science Journal, Vol. 62, March

8 COWAN, W.D. (1995) The relevance of intestinal viscosity on performance of practical broiler diets. Proceedings of the Australian Poultry Science Symposium 7: D ALFONSO, T.H. (2003) Factors affecting ileal digestible energy of corn in poultry diets. Proceedings of the Recent Advances in Animal Nutrition in Australia 14: (Corbett, J.L, ed.), University of New England, Armidale, NSW 2351, Australia. DANICKE, S. SIMON, O. and JEROCH, H. (1999) Effects of supplementation of xylanase or β-glucanase containing enzyme preparations to either rye- or barley-based diets on performance and nutrient digestibility. Archiv für Geflügelkunde 63: FENGLER A.I. and MARQUARDT, R.R. (1988b) Water-soluble arabinoxylans from rye: II. Effects of rate of dialysis and on the retention of nutrients by the chick. Cereal Chemistry 65: FENGLER, A.I. and MARQUARDT, R.R. (1988a) Water-soluble pentosans from rye: I. Isolation, partial purification, and characterisation. Cereal Chemistry 65: FERNANDEZ, R., LUCAS, E. and McGINNIS, J. (1973) Fractionation of a chick growth depressing factor from rye. Poultry Science 52: FRY, R.E., ALLRED, J.B., JENSEN, L.S. and McGINNIS, J. (1957) Influence of cereal grain components of the diet on the response of chicks and poults to dietary enzyme supplements. Poultry Science 36: HASTINGS, W.H. (1946) Enzyme supplements for poultry feeds. Poultry Science 25: HESSELMAN, K. and ÅMAN, P. (1986) The effect of β-glucanase on the utilization of starch and nitrogen by broiler chickens fed on barley of low or high viscosity. Animal Feed Science and Technology 15: HUO, G.C., FOWLER, V.R., INBORR, J. and BEDFORD, M.R. (1993) The use of enzymes to denature antinutritive factors in soybean. Proceedings of the 2nd International Workshop on ANFs in Legume Seed, p.60, Wageningen, The Netherlands. KOCHER, A., CHOCT, M., PORTER, M.D. and BROZ, J. (2002) Effects of feed enzymes on nutritive value of soybean meal fed to broilers. British Poultry Science 43: KORNEGAY, E.T. (2001) Digestion of phosphorus and other nutrients: the role of phytases and factors influencing their activity. Enzymes in Farm Animal Nutrition, (Bedford, M.R. and Partridge, G.G., eds.), pp CABI Publishing, London. LAWRENCE, T.L.J., ROWAN,T.G., PRESTON, M.R. and TURTLE, L.P. (1995) Effect of total intact glucosinolate intake from rapeseed meals with or without thioglucosidase (EC ) or copper additions to the diet on the concentrations of 1-cyano-2-hydroxy-3-butene in the ileal digesta and faeces of growing pigs. Animal Feed Science and Technology 51: NEWMAN, R.K. and NEWMAN, C.W. (1987) Beta-glucanase effect on the performance of broiler chicks fed covered and hulless barley isotypes having normal and waxy starch. Nutrition Reports International 36: PETTERSON, D. and ÅMAN, P. (1989) Enzyme supplementation of a poultry diet containing rye and wheat. British Journal of Nutrition 62: PETTERSSON, D. and ÅMAN, P. (1988) Effects of enzyme supplementation of diets based on wheat, rye or triticale on their productive value for broiler chickens. Animal Feed Science and Technology 20: RAVINDRAN, V., CABAHUG, S., RAVINDRAN, G., SELLE, P.H. and BRYDEN, W.L. (1999) Influence of microbial phytase on apparent ileal amino acid digestibility of feedstuffs for broilers. Poultry Science 78: RAVINDRAN, V., CABAHUG, S., RAVINDRAN, G., SELLE, P.H. and BRYDEN, W.L. (1999) Response of broiler chickens to microbial phytase supplementation as influenced by dietary phutic acid and non-phytate phopophorus levels: II. Effects on apparent metabolisable energy, nutrient digestibility and nutrient reteneiton. British Poultry Science 41: SAUNDERS, R.M. (1986) Rice bran: composition and potential food uses. Food Reviews International 1: SINLAE, M. and CHOCT, M. (2000) Xylanase supplementation affects the gut microflora of broilers. Australian Poultry Science Symposium 12: 209. SPIEHS, M.J., WHITNEY, M.H. and SHURSON, G.C. (2002) Nutrient database for distiller s dried grains with solubles produced from new ethanol plants in Minnesota and South Dakota. Journal of Animal Science 80: SPRING, P., WENK, C., DAWSON, K.A. and NEWMAN, K.E. (2000) The effects of dietary mannaoligosaccharides on cecal parameters and the concentrations of enteric bacteria in the ceca of salmonella-challenged broiler chicks. Poultry Science 79: VAHJEN, W., GLÄSER, K., SCHÄFER, K. and SIMON, O. (1998) Influence of xylanase-supplemented feed on the development of selected bacterial groups in the intestinal tract of broiler chicks. Journal of Agricultural Science 130: WISEMAN, J. and MCNAB, J.M. (1998) Nutritive value of wheat varieties fed to non-ruminants. HGCA Project Report No Home Grown Cereals Authority. 12 World s Poultry Science Journal, Vol. 62, March 2006

9 Figure 1 The chemical structure of a pectic polymer from Lupinus Angustifolius (Cheetham et al., 1993). Table 1 The types and levels of NSP present in some cereal grains (% dry matter). Cereal Arabinoxylan β-glucan Cellulose Man Gal Uronic Acid Total Wheat 1 Soluble t 0.2 t 2.4 Insoluble t Barley Soluble t 0.1 t 4.5 Insoluble Rye Soluble Insoluble Oats Soluble t Insoluble t 24.5 Triticale Soluble Insoluble Sorghum Soluble t t t 0.2 Insoluble t 4.6 Corn Soluble 0.1 t t t t 0.1 Insoluble t 8.0 Rice (pearled) Soluble t 0.1 t Insoluble t t t 0.5 Millet Soluble t t 0 t t 0.2 Insoluble World s Poultry Science Journal, Vol. 62, March

10 Table 2 The types and levels of carbohydrate polymers and monomers in selected legumes (% dry matter). Sample Starch Total NSP Cellulose Rhamnose Fucose Arabinose Xylose Mannose Galactose Glucose U.Ac 1 Soybean 2 Soluble t Insoluble Total Lupins 3 Soluble t t t t Insoluble t Total t Faba beans 3 Soluble ND Insoluble ND ND Total Chckpeas 3 Soluble ND Insoluble ND ND Total Field peas 3 Soluble ND Insoluble ND ND Total Mungbean 3 Soluble ND Insoluble 8.17 ND ND Total Uronic acids; 2 From Irish and Balnave (1993); 3 Choct et al., unpublished data. ND = not determined 14 World s Poultry Science Journal, Vol. 62, March 2006

11 Table 3 Jejunal and ileal viscosity, and the contents of free sugars and soluble NSP in the jejunum of broiler chickens fed a wheat-based diet with and without enzyme supplementation. Diet Viscosity (mpa.s) Jejunal (mg/g marker) Jejunum Ileum Free Sugars Soluble NSP Control 9.4 b 28.3 b c b Xylanase A 5.2 c 8.3 c a a Xylanase B 18.4 a 84.1 a a a Xylanase C 3.4 c 7.2 c b b abc Means in a column sharing a common superscript do not differ significantly (P<0.05). Table 4 Growth rate, feed conversion ratio (FCR), apparent metabolisable energy of wheat in broiler chickens fed on diets containing normal-me wheat and low-me wheat with and without enzyme supplementation. Weight gain FCR AME of wheat Wheat Enzyme g/bird/week g feed / g gain MJ/kg DM Normal-ME wheat Control 345 ± 33 c ± a 13.7 ± 0.5 ab Normal-ME wheat Xylanase A 392 ± 20 ab ± bc 14.5 ± 0.4 ab Normal-ME wheat Xylanase B 395 ± 29 ab ± bc 13.9 ± 0.9 ab Normal-ME wheat Xylanase C 383 ± 33 ab ± abc 14.2 ± 0.7 ab Low-ME wheat Control 369 ± 24 c ± ab 12.7 ± 0.6 c Low-ME wheat Xylanase A 410 ± 31 a ± c 13.6 ± 0.9 ab Low-ME wheat Xylanase B 385 ± 12 ab ± bc 13.3 ± 0.4 bc Low-ME wheat Xylanase C 401 ± 23 ab ± c 13.9 ± 0.8 ab Source of variance Wheat NS NS *** Enzyme *** *** *** Wheat*Enzyme NS NS NS a,b,c Values with unlike superscripts in the same column differ significantly (P<0.05) 1 ***P<0.001 World s Poultry Science Journal, Vol. 62, March

12 16 World s Poultry Science Journal, Vol. 62, March 2006