Urea transport and hydrolysis in the rumen: A review

作     者：Samson Hailemariam Shengguo Zhao Yue He Jiaqi Wang Samson Hailemariam;Shengguo Zhao;Yue He;Jiaqi Wang

作者机构：State Key Laboratory of Animal NutritionInstitute of Animal SciencesChinese Academy of Agricultural SciencesBeijing100193China Dilla UniversityCollege of Agriculture and Natural ResourceDilla P.O.Box 419Ethiopia 

出 版 物：《Animal Nutrition》 (动物营养（英文版）)

年 卷 期：2021年第7卷第4期

页      面：989-996页

核心收录：

学科分类：090601[农学-基础兽医学] 0905[农学-畜牧学] 09[农学] 0906[农学-兽医学] 

基　　金：funded by the National Key Research and Development Program(2017YFD0500502) National Natural Science Foundation of China(31430081) The Scientific Research Project for Major Achievements of The Agricultural Science and Technology Innovation Program(ASTIP)(No.CAAS-ZDXT2019004) Modern Agro-Industry Technology Research System of the PR China(CARS-36)。 

主　　题：Urea transporter Urea Urea hydrolysis Ruminal bacteria 

摘      要：Inefficient dietary nitrogen(N)conversion to microbial proteins,and the subsequent use by ruminants,is a major research focus across different fields.Excess bacterial ammonia(NH3)produced due to degradation or hydrolyses of N containing compounds,such as urea,leads to an inefficiency in a host’s ability to utilize nitrogen.Urea is a non-protein N containing compound used by ruminants as an ammonia source,obtained from feed and endogenous sources.It is hydrolyzed by ureases from rumen bacteria to produce NH_(3) which is used for microbial protein synthesis.However,lack of information exists regarding urea hydrolysis in ruminal bacteria,and how urea gets to hydrolysis sites.Therefore,this review describes research on sites of urea hydrolysis,urea transport routes towards these sites,the role and structure of urea transporters in rumen epithelium and bacteria,the composition of ruminal ureolytic bacteria,mechanisms behind urea hydrolysis by bacterial ureases,and factors influencing urea hydrolysis.This review explores the current knowledge on the structure and physiological role of urea transport and ureolytic bacteria,for the regulation of urea hydrolysis and recycling in ruminants.Lastly,underlying mechanisms of urea transportation in rumen bacteria and their physiological importance are currently unknown,and therefore future research should be directed to this subject.