Vanzant E S, Cochran R C, Titgemeyer E C
Agricultural Research Center--Hays, Kansas State University, 67601, USA.
J Anim Sci. 1998 Oct;76(10):2717-29. doi: 10.2527/1998.76102717x.
Over the last two decades, in situ techniques have been used extensively for measuring ruminal degradation of feedstuffs. Current predictive models put renewed emphasis on the need for quantitative information regarding rates and extents of ruminal degradation. However, in situ techniques suffer from tremendous variation, both within and among laboratories. A considerable number of studies have evaluated the influence of various factors on in situ-derived estimates of ruminal degradation. Factors that should be addressed in a standardized procedure include bag and sample sizes; bag material and pore size; sample processing; animal diet, feeding level, and frequency; bag insertion and removal procedures; location of bags within the rumen and containment procedures for the bags; rinsing procedures; microbial correction; incubation times; mathematical models; and numbers of replicate animals, days, and bags required to obtain repeatable estimates of ruminal degradation. Several recommendations that should increase the precision of in situ measurements are presented. Currently, the lack of standardization in rinsing techniques and the failure or inability to correct for microbial contamination of in situ residues seem to be the major sources of variability with in situ procedures.
在过去二十年中，原位技术已被广泛用于测定饲料的瘤胃降解率。当前的预测模型再次强调了获取瘤胃降解率和降解程度定量信息的必要性。然而，原位技术在不同实验室内部和之间都存在巨大差异。大量研究评估了各种因素对原位法测定瘤胃降解率的影响。标准化程序中应考虑的因素包括袋和样本大小；袋材料和孔径；样本处理；动物饮食、采食量和采食频率；袋的插入和取出程序；瘤胃内袋的位置以及袋的固定程序；冲洗程序；微生物校正；培养时间；数学模型；以及为获得可重复的瘤胃降解率估计值所需的重复动物数量、天数和袋数。本文提出了一些能够提高原位测量精度的建议。目前，冲洗技术缺乏标准化以及未能或无法校正原位残留物的微生物污染似乎是原位法变异的主要来源。
