Xylose: absorption, fermentation, and post-absorptive metabolism in the pig

作     者：Nichole F.Huntley John F.Patience 

作者机构：Department of Animal Science213 Kildee HallIowa State University Department of Animal Science201B Kildee HallIowa State University 

出 版 物：《Journal of Animal Science and Biotechnology》 (畜牧与生物技术杂志（英文版）)

年 卷 期：2018年第9卷第1期

页      面：1-9页

核心收录：

学科分类：090502[农学-动物营养与饲料科学] 0905[农学-畜牧学] 09[农学] 

基　　金：supported in part by grants from Iowa Pork Producers Association and Elanco Animal Health 

主　　题：Pentose utilization Swine Threitol Xylose absorption Xylose metabolism 

摘      要：Xylose, as β-1,4-linked xylan, makes up much of the hemicel ulose in cel wal s of cereal carbohydrates fed to pigs. As inclusion of fibrous ingredients in swine diets continues to increase, supplementation of carbohydrases, such as xylanase,is of interest. However, much progress is warranted to achieve consistent enzyme efficacy, including an improved understanding of the utilization and energetic contribution of xylanase hydrolysis product（i.e. xylooligosaccharides or monomeric xylose）. This review examines reports on xylose absorption and metabolism in the pig and identifies gaps in this knowledge that are essential to understanding the value of carbohydrase hydrolysis products in the nutrition of the pig. Xylose research in pigs was first reported in 1954, with only sporadic contributions since. Therefore, this review also discusses relevant xylose research in other monogastric species, including humans. In both pigs and poultry, increasing purified D-xylose inclusion general y results in linear decreases in performance, efficiency, and diet digestibility. However,supplementation levels studied thus far have ranged from 5% to 40%, while theoretical xylose release due to xylanase supplementation would be less than 4%. More than 95% of ingested D-xylose disappears before the terminal ileum but mechanisms of absorption have yet to be ful y elucidated. Some data support the hypothesis that mechanisms exist to handle low xylose concentrations but become overwhelmed as luminal concentrations increase. Very little is known about xylose metabolic utilization in vertebrates but it is wel recognized that a large proportion of dietary xylose appears in the urine and significantly decreases the metabolizable energy available from the diet. Nevertheless, evidence of labeled D-xylose-1-^（14）C appearing as expired^（14）CO_2 in both humans and guinea pigs suggests that there is potential,although small, for xylose oxidation. It is yet to be determined if pigs develop increased xy