Leng R A, Nolan J V
J Dairy Sci. 1984 May;67(5):1072-89. doi: 10.3168/jds.S0022-0302(84)81409-5.
Nitrogen metabolism is reviewed with emphasis on methods for quantitating various nitrogen-transactions in the rumen of animals on a variety of diets. Ammonia kinetics, microbial cell synthesis, the inputs of endogenous nitrogen, degradation of dietary protein, and availability to the animal of dietary bypass protein are discussed. The efficiency of microbial protein from the rumen is discussed in relation to the ratio of protein to energy in the nutrients available to meet the requirements of the animal. The ratio is determined largely by the maintenance requirements of microbes and the breakdown of microbial materials, which result in the recycling of microbial nitrogen in the rumen. Emphasis is placed on the role of rumen protozoa in decreasing the ratio of protein to energy in absorbed nutrients in ruminants on diets that are marginally deficient in protein. Recent studies of the dynamics of protozoa in the rumen and their contribution to microbial protein outflow are summarized.
本文综述了氮代谢，重点关注定量各种日粮条件下动物瘤胃中氮转化的方法。讨论了氨动力学、微生物细胞合成、内源氮输入、日粮蛋白质降解以及日粮过瘤胃蛋白对动物的可利用性。结合满足动物需求的可用营养素中蛋白质与能量的比例，讨论了瘤胃微生物蛋白的效率。该比例很大程度上取决于微生物的维持需求和微生物物质的分解，这导致瘤胃中微生物氮的循环利用。重点探讨了瘤胃原生动物在蛋白质略微缺乏的日粮条件下反刍动物吸收养分中降低蛋白质与能量比例方面的作用。总结了近期关于瘤胃中原生动物动态及其对微生物蛋白流出贡献的研究。
