Cereal grains, such as wheat and corn, are commonly used as a primary source of energy in broiler diets. However, these grains are rich in non-starch polysaccharides (NSPs), particularly arabinoxylan (AX). High levels of soluble AXs generate digesta viscosity. The increased viscosity leads to decreased transit rate, limited contact between digestive enzymes and substrates, and increased bacterial fermentation in the small intestine, thus resulting in poor growth performance of broilers. It was found that supplementation of xylanases and debranching enzymes of glycoside hydrolases family 43 (GH43) in the wheat-based diet showed a significant reduction in viscosity. In vivo studies indicated the enhanced release of arabinose and xylose residues in ilium and jejunum, suggesting the degradation of AX and, in turn, reduction of digesta viscosity. In addition, xylan oligomers derived from AX degradation stimulated the abundant growth and proliferation of the bacteria in the clusters of Lactobacillaceae, Enterococcaceae, Clostridiaceae, Lachnospiraceae, and Ruminococcaceae in the gut microbiome, suggesting the prebiotic effects. Quantification of short-chain fatty acids in the ceca of the broiler gut fed with GH43 xylanases showed the increased concentration of butyrate, which might be responsible for immune system stimulation and might explain better feed intake. Overall, supplementation of GH43 and other related enzymes in broiler diets is an attractive means to improve growth performance and gut health of broilers. References de Camargo, B.R., Claassens, N.J., Quirino, B.F., Noronha, E.F. and Kengen, S.W.M., 2018, "Heterologous Expression and Characterization of a Putative Glycoside Hydrolase Family 43 Arabinofuranosidase from Clostridium thermocellum B8", Enzyme Microb Technol, Vol. 109, pp. 74-83. Hassan, N., Kori, L.D., Gandini, R., Patel, B.K., Divne, C. and Tan, T.C., 2015, "High-Resolution Crystal Structure of a Polyextreme GH43 Glycosidase from Halothermothrix orenii with α-L-Arabinofuranosidase Activity", Acta Crystallogr F Struct Biol Commun, Vol. 71, pp. 338-45. Hosseini, S.M. and Afshar, M., 2016, "Effects of Feed Form and Xylanase Supplementation on Performance and Ileal Nutrients Digestibility of Heat-Stressed Broilers Fed Wheat–Soybean Diet", J Appl Anim Res, Vol. 45, pp. 550-556. Lei, Z., Shao, Y., Yin, X., Yin, D., Guo, Y. and Yuan, J., 2016, "Combination of Xylanase and Debranching Enzymes Specific to Wheat Arabinoxylan Improve the Growth Performance and Gut Health of Broilers", J Agric Food Chem, Vol. 64, pp. 4932-42. Mechelke, M., Koeck, D.E., Broeker, J., Roessler, B., Krabichler, F., Schwarz, W.H., Zverlov, V.V. and Liebl, W., 2017, "Characterization of the Arabinoxylan-Degrading Machinery of the Thermophilic Bacterium Herbinix hemicellulosilytica-Six New Xylanases, Three Arabinofuranosidases and One Xylosidase", J Biotechnol, Vol. 257,pp. 122-130. Yacoubi, N., Saulnier, L., Bonnin, E., Devillard, E., Eeckhaut, V., Rhayat, L., Ducatelle, R. and Van Immerseel, F., 2017, “Short-chain Arabinoxylans Prepared from Enzymatically Treated Wheat Grain Exert Prebiotic Effects During the Broiler Starter Period” Poult Sci, Vol. 97, pp.412-424. Zhang, L., Xu, J., Lei, L., Jiang, Y., Gao, F. and Zhou, G.H., 2014, "Effects of Xylanase Supplementation on Growth Performance, Nutrient Digestibility and Non-Starch Polysaccharide Degradation in Different Sections of the Gastrointestinal Tract of Broilers Fed Wheat-Based Diets", Asian-Australas J Anim Sci, Vol. 27, pp. 855-61.