FACTORS AFFECTING THE UTILIZATION OF POOR-QUALITY FORAGES BY RUMINANTS PARTICULARLY UNDER TROPICAL CONDITIONS
FACTORS AFFECTING THE UTILIZATION OF POOR-QUALITY FORAGES BY RUMINANTS PARTICULARLY UNDER TROPICAL CONDITIONS
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DOI：
10.1079/nrr19900016
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发表时间：
1990-01-01
影响因子：
5.7
通讯作者：
LENG R A
中科院分区：
文献类型：
--
作者：
LENG R A
反刍动物将“低质量”粗饲料用于生产目的的效率受到与饲料或动物有关的许多因素的影响。这些因素包括：(1)饲料中微生物营养素的可用性，以支持微生物的高效生长，以及瘤胃内的高消化率和高消化程度，进而优化采食量；(2)饲料中可溶性细胞成分与难消化细胞壁碳水化合物的比率。这一比率显著影响瘤胃主要微生物(如细菌、真菌和原生动物)的种群密度组合；(3)动物的生理状态和以往的饮食及健康史，决定了所需营养素的数量需求和平衡；(4)热环境，决定了维持体温所需的底物氧化需要，并改变了可用于合成代谢功能的营养素的平衡；(5)饲料的化学和物理特性，决定了微生物发酵消化的饲料比例和避开瘤胃发酵而可在肠道消化和吸收的日粮营养素。在实验室条件下，许多因素可以被分离和详细研究，但很少有研究试图同时阐明导致动物最终产品利用效率的许多因素的相互作用。通常，在一个地点进行的喂养试验得出的结果与在另一个地点发现的结果相矛盾。大量的时间和精力被浪费在试图反驳从一组条件下获得的数据得出的结论，这些条件不能重复，并且在另一组条件下往往是令人难以置信的。在本演示中，假设文献中报告的研究结果很少是错误的，但正是不同条件的不同影响和相互作用导致了往往不同的结论。本文试图解释表面上相互矛盾的结果之间的一些主要差异。从消化道吸收的营养素的数量与特定生理条件的需求非常接近，这被认为可以凌驾于大量其他因素之上，并决定反刍动物利用饲料进行生产的效率。
The efficiency of utilization of'low-quality'roughages by ruminants for productive purposes is altered by numerous factors which are associated with the feed or the animal. These include:(1) the availability of microbial nutrients in the feed to support an efficient microbial growth, and a high rate and extent of digestion in the rumen which in turn optimizes intake;(2) the ratio of soluble cell components to refractory cell wall carbohydrates in the forage. This ratio markedly affects the population density-mix of the major microorganisms in the rumen (eg bacteria, fungi and protozoa);(3) the physiological state and previous dietary and health history of the animal which determines the quantitative demand for and balance of nutrients required;(4) the thermal environment which determines the requirements for substrate oxidation for maintenance of body temperature and alters the balance of nutrients available for anabolic functions;(5) the chemical and physical characteristics of forage which determine the proportion of feed digested by microbial fermentation and the dietary nutrients that escape rumen fermentation and are available for digestion and absorption in the intestines. Under laboratory conditions many of the factors can be isolated and studied in detail, but few studies have attempted to elucidate simultaneously the interactions of the many factors that result in the efficiency of end-product utilization by the animal. Often feeding trials done in one location have given results that contradict those found in another. Much time and effort has been wasted attempting to disprove theses developed from data acquired under one set of conditions which cannot be repeated and are often unbelievable under another set of conditions.In this presentation it has been assumed that research results reported in the literature are rarely erroneous, but it is the varying effects and interactions of differing conditions which result in often disparate conclusions. An attempt is made to explain some of the major differences between apparently conflicting results. The absorption of nutrients from the digestive tract in quantities closely approximating the demand for specific physiological conditions is considered to override a large number of other factors and to determine the efficiency with which a ruminant uses its feed for production.