Chen C P J, Ferreira G
School of Animal Sciences, Virginia Tech, Blacksburg 24060.
JDS Commun. 2022 Dec 14;4(2):166-168. doi: 10.3168/jdsc.2022-0304. eCollection 2023 Mar.
A pregnancy loss or abortion can be assumed when a dairy cow that has been previously diagnosed pregnant shows signs of estrus. In herds using leg-based pedometers as a tool to detect cows in estrus, a sudden increase in walking activity (hereafter, activity peaks) relative to a certain threshold activity triggers an estrous alert that can be confused with a pregnancy loss. The objective of this study was to determine whether pregnant cows can show activity peaks as measured by pedometers. We used data from a dairy herd of 250 milking cows using pedometers as a means of measuring walking activity to detect cows in estrus. Two databases were used in this study, which included the walking activity of the entire herd recorded by the pedometers from January 1, 2018, to December 31, 2021 (database 1), and the calving dates, the insemination dates, the dates when a pregnancy diagnosis was declared pregnant, the dates when a pregnancy diagnosis was declared not pregnant or open, and the abortion dates (database 2). Activity peaks were identified within an experimental unit, which was defined as pregnant cows showing an insemination event followed by a confirmed pregnancy and subsequent calving. The activity peaks were identified using the peak searching algorithm that compares the step count on a given day with the step counts of its adjacent days. The candidate peaks were characterized for their magnitudes by the prominence metric. A chi-squared test was performed to test the specificity of the system. From the 4-yr database, 537 pregnancies or experimental units were identified, and 77 pregnancies showed 1 or more peaks, which means that 14.4% of the pregnancies showed activity peaks. Within the pregnancies showing peaks (n = 77), the median equaled 1 peak/pregnancy, the average equaled 1.53 peaks/pregnancy, and the maximum equaled 13 peaks/pregnancy. In conclusion, activity peaks can be observed for pregnant cows using pedometers. These peaks could generate false estrous alerts during the pregnancy period when using pedometers, and these false alerts should not be interpreted as pregnancy losses.
当先前已诊断怀孕的奶牛出现发情迹象时，可认定发生了妊娠丢失或流产。在使用基于腿部的计步器作为检测奶牛发情工具的牛群中，相对于某个阈值活动，行走活动突然增加（以下简称活动峰值）会触发发情警报，这可能会与妊娠丢失相混淆。本研究的目的是确定怀孕奶牛是否会出现计步器测量的活动峰值。我们使用了来自一个拥有250头泌乳奶牛的奶牛场的数据，该奶牛场使用计步器作为测量行走活动以检测奶牛发情的手段。本研究使用了两个数据库，其中包括计步器记录的2018年1月1日至2021年12月31日整个牛群的行走活动（数据库1），以及产犊日期、授精日期、宣布怀孕的妊娠诊断日期、宣布未怀孕或空怀的妊娠诊断日期以及流产日期（数据库2）。在一个实验单元内识别活动峰值，该实验单元定义为显示授精事件、随后确认怀孕并随后产犊的怀孕奶牛。使用峰值搜索算法识别活动峰值，该算法将给定日期的步数与其相邻日期的步数进行比较。通过突出度指标对候选峰值的大小进行表征。进行卡方检验以测试该系统的特异性。从4年的数据库中，识别出537次怀孕或实验单元，77次怀孕出现了1个或更多峰值，这意味着14.4%的怀孕出现了活动峰值。在出现峰值的怀孕中（n = 77），中位数为每次怀孕1个峰值，平均值为每次怀孕1.53个峰值，最大值为每次怀孕13个峰值。总之，使用计步器可以观察到怀孕奶牛出现活动峰值。在怀孕期间使用计步器时，这些峰值可能会产生错误的发情警报，并且这些错误警报不应被解释为妊娠丢失。
