Animal Nutrition Group, Wageningen University & Research, 6700 AHWageningen, the Netherlands.
Wageningen Livestock Research, Wageningen University & Research, 6700 AHWageningen, the Netherlands.
Animal. 2020 Mar;14(S1):s176-s186. doi: 10.1017/S1751731119003112.
Rumen sensors provide specific information to help understand rumen functioning in relation to health disorders and to assist in decision-making for farm management. This review focuses on the use of rumen sensors to measure ruminal pH and discusses variation in pH in both time and location, pH-associated disorders and data analysis methods to summarize and interpret rumen pH data. Discussion on the use of rumen sensors to measure redox potential as an indication of the fermentation processes is also included. Acids may accumulate and reduce ruminal pH if acid removal from the rumen and rumen buffering cannot keep pace with their production. The complexity of the factors involved, combined with the interactions between the rumen and the host that ultimately determine ruminal pH, results in large variation among animals in their pH response to dietary or other changes. Although ruminal pH and pH dynamics only partially explain the typical symptoms of acidosis, it remains a main indicator and may assist to optimize rumen function. Rumen pH sensors allow continuous monitoring of pH and of diurnal variation in pH in individual animals. Substantial drift of non-retrievable rumen pH sensors, and the difficulty to calibrate these sensors, limits their application. Significant within-day variation in ruminal pH is frequently observed, and large distinct differences in pH between locations in the rumen occur. The magnitude of pH differences between locations appears to be diet dependent. Universal application of fixed conversion factors to correct for absolute pH differences between locations should be avoided. Rumen sensors provide high-resolution kinetics of pH and a vast amount of data. Commonly reported pH characteristics include mean and minimum pH, but these do not properly reflect severity of pH depression. The area under the pH × time curve integrates both duration and extent of pH depression. The use of this characteristic, as well as summarizing parameters obtained from fitting equations to cumulative pH data, is recommended to identify pH variation in relation to acidosis. Some rumen sensors can also measure the redox potential. This measurement helps to understand rumen functioning, as the redox potential of rumen fluid directly reflects the microbial intracellular redox balance status and impacts fermentative activity of rumen microorganisms. Taken together, proper assessment and interpretation of data generated by rumen sensors requires consideration of their limitations under various conditions.
瘤胃传感器提供特定信息，有助于了解瘤胃功能与健康障碍的关系，并为农场管理决策提供帮助。本综述重点介绍了使用瘤胃传感器测量瘤胃 pH 值的情况，并讨论了 pH 值在时间和位置上的变化、与 pH 值相关的疾病以及总结和解释瘤胃 pH 值数据的数据分析方法。还讨论了使用瘤胃传感器测量氧化还原电位作为发酵过程的指示。如果瘤胃中酸的清除和瘤胃缓冲不能与酸的产生保持同步，酸可能会积累并降低瘤胃 pH 值。参与的因素的复杂性，加上瘤胃和宿主之间的相互作用，最终导致动物对饮食或其他变化的 pH 反应存在很大差异。尽管瘤胃 pH 值和 pH 值动态仅部分解释酸中毒的典型症状，但它仍然是主要指标，并可能有助于优化瘤胃功能。瘤胃 pH 值传感器可连续监测单个动物的 pH 值和 pH 值的昼夜变化。不可回收的瘤胃 pH 值传感器的大量漂移，以及校准这些传感器的困难，限制了它们的应用。瘤胃 pH 值的日内变化很大，瘤胃内不同部位的 pH 值也存在明显差异。不同部位之间 pH 值的差异幅度似乎与饮食有关。应避免使用固定的转换因子来校正不同部位之间的绝对 pH 值差异。瘤胃传感器提供 pH 值的高分辨率动力学和大量数据。通常报道的 pH 值特征包括平均值和最小 pH 值，但这些特征不能正确反映 pH 值下降的严重程度。pH 值与时间曲线下的面积综合了 pH 值下降的持续时间和程度。建议使用该特征以及从累积 pH 值数据拟合方程中获得的汇总参数来识别与酸中毒相关的 pH 值变化。一些瘤胃传感器还可以测量氧化还原电位。这种测量有助于了解瘤胃功能，因为瘤胃液的氧化还原电位直接反映了微生物细胞内氧化还原平衡状态，并影响瘤胃微生物的发酵活性。总之，要正确评估和解释瘤胃传感器产生的数据，需要考虑在各种条件下它们的局限性。
