Animal Welfare Program, University of British Columbia, 2357 Mall, Vancouver, BC, Canada, V6T 1Z4.
Animal Welfare Program, University of British Columbia, 2357 Mall, Vancouver, BC, Canada, V6T 1Z4.
J Dairy Sci. 2019 Apr;102(4):3495-3500. doi: 10.3168/jds.2018-15585. Epub 2019 Feb 1.
The objective of this study was to determine whether data from an electronic drinking system that tracks individual animal attendance with ear tag transponders could be used to detect social competition between dairy cows at the drinker. Specifically, we sought to identify the interval between one cow leaving the drinker and another cow taking her place that most accurately identified competitive replacements (when physical contact initiated by one cow causes the other to entirely remove her head from the drinker and the initiator subsequently places her head in the same drinker). The optimal interval to accurately identify replacements at the drinker was determined using a receiver operating characteristic curve and by evaluating the sensitivity (Se), specificity (Sp), and confusion matrix values (true positives, true negatives, false positives, false negatives) of different thresholds identified by 3 metrics: the Youden index, the point closest to (0,1) on the curve, and the point where Se roughly equals Sp. Lactating Holstein dairy cows (n = 20) were monitored for 4 consecutive 24-h periods by video recording and with an electronic drinking system. Two periods were used to identify the optimal interval (the baseline set), and the other 2 periods were used to validate the interval (the validation set). The occurrence of a replacement identified by video was paired with the interval between drinking events of 2 cows at the same electronic drinker to identify the interval that best predicted replacement events. Based on the low prevalence of replacement events compared with nonreplacement events, the interval with the lowest number of false positives was considered optimal. Of the 3 potential metrics, the point on the receiver operating characteristic curve where Se and Sp were roughly equal yielded the fewest false positives. The optimal interval to identify replacements at the drinker was ≤29 s, with 82% Se and 83% Sp in the baseline set. This interval was found to have 85% Se and 89% Sp when applied to the validation set. These results indicate that social competition between dairy cows at the drinker can be accurately measured with an electronic drinking system.
本研究旨在确定一种通过耳标标签追踪个体动物出勤情况的电子饮水系统数据是否可用于检测奶牛在饮水器处的社会竞争。具体而言，我们试图确定一头奶牛离开饮水器和另一头奶牛接替她的时间间隔，该间隔能最准确地识别竞争接替（当一头奶牛通过身体接触导致另一头奶牛完全将头从饮水器中移出，而发起者随后将头放在同一个饮水器中时）。使用接收者操作特征曲线和评估不同阈值的敏感性（Se）、特异性（Sp）和混淆矩阵值（真阳性、真阴性、假阳性、假阴性），确定准确识别饮水器处替代者的最佳时间间隔。通过 3 种指标（Youden 指数、曲线最接近（0，1）的点和 Se 大致等于 Sp 的点）确定不同阈值，并通过 3 种指标确定不同阈值：Youden 指数、曲线最接近（0，1）的点和 Se 大致等于 Sp 的点。对 20 头泌乳荷斯坦奶牛进行了 4 个连续 24 小时的视频记录和电子饮水系统监测。两个时间段用于确定最佳间隔（基线设置），其余两个时间段用于验证间隔（验证集）。通过视频识别的替代事件与同一电子饮水器的 2 头奶牛的饮水事件之间的间隔配对，以确定最佳预测替代事件的间隔。基于替代事件与非替代事件相比发生率较低，具有最少假阳性的间隔被认为是最佳的。在 3 种潜在指标中，Se 和 Sp 大致相等的接收器操作特征曲线的点产生的假阳性最少。在基线集中，识别饮水器处替代者的最佳间隔时间≤29 秒，Se 为 82%，Sp 为 83%。当应用于验证集时，该间隔时间的 Se 为 85%，Sp 为 89%。这些结果表明，通过电子饮水系统可以准确测量奶牛在饮水器处的社会竞争。
