hIn broiler chickens, feed additives, including prebiotics, are widely used to improve gut health and to stimulate performance. Xylo-oligosaccharides (XOS) are hydrolytic degradation products of arabinoxylans that can be fermented by the gut microbiota. In the current study, we aimed to analyze the prebiotic properties of XOS when added to the broiler diet. Administration of XOS to chickens, in addition to a wheat-rye-based diet, significantly improved the feed conversion ratio. XOS significantly increased villus length in the ileum. It also significantly increased numbers of lactobacilli in the colon and Clostridium cluster XIVa in the ceca. Moreover, the number of gene copies encoding the key bacterial enzyme for butyrate production, butyryl-coenzyme A (butyryl-CoA):acetate CoA transferase, was significantly increased in the ceca of chickens administered XOS. In this group of chickens, at the species level, Lactobacillus crispatus and Anaerostipes butyraticus were significantly increased in abundance in the colon and cecum, respectively. In vitro fermentation of XOS revealed cross-feeding between L. crispatus and A. butyraticus. Lactate, produced by L. crispatus during XOS fermentation, was utilized by the butyrate-producing Anaerostipes species. These data show the beneficial effects of XOS on broiler performance when added to the feed, which potentially can be explained by stimulation of butyrate-producing bacteria through cross-feeding of lactate and subsequent effects of butyrate on gastrointestinal function.
Cereal fibers are composed of carbohydrate polymers that are resistant to digestion in the small intestines of monogastric animals but are completely or partially fermented in the distal gut, and they are believed to stimulate gut health (1). The main components of the cereal fiber fraction are arabinoxylans (AX), pectins, resistant starch, cellulose, -glucans, and lignin (2). Hydrolytic degradation of the heteropolymer AX results in a mixture of arabinose-substituted xylo-oligosaccharides (arabinoxylan-oligosaccharides) (AXOS) and nonsubstituted xylo-oligosaccharides (XOS) (3). XOS are oligomers consisting of xylose units linked through -(1-4) linkages (4). Selective fermentation of XOS has been shown to induce changes in both the composition and activity of the gastrointestinal microbiota, improving the health and well-being of the host. This suggests that XOS could fulfill the definition of a prebiotic (5). The production of lactate and shortchain fatty acids (SCFA), including butyrate, upon fermentation of XOS, has been confirmed in several in vitro and in vivo studies (3, 6). Lactate can stimulate butyrate production due to crossfeeding between lactate-producing bacteria and lactate-utilizing butyrate-producing bacteria from Clostridium cluster XIVa (7). Butyrate has proven beneficial effects on gastrointestinal function, since it has anti-inflammatory properties, fuels epithelial cells, and increases the intestinal epithelial integrity. In addition, butyrate has been shown to improve growth pe...
