Department of Sustainable Agricultural Systems, University of Natural Resources and Life Sciences, 1180 Vienna, Austria.
Department of Ethology and Companion Animal Science, Czech University of Life Sciences, 165 00 Prague, Czech Republic; Department of Ethology, Institute of Animal Science, 104 00 Praha Uhříněves, Czech Republic.
J Dairy Sci. 2020 Feb;103(2):1866-1873. doi: 10.3168/jds.2019-17005. Epub 2019 Nov 20.
Play behavior is a promising welfare indicator in dairy calves because it decreases in negative situations such as pain or hunger and increases in positive contexts such as in appropriate social environments. Directly measuring play is time consuming because it is performed in irregular bouts and can be inconsistent over days. To facilitate automatic recording of play, previous studies fitted triaxial accelerometers to the hind legs of calves and measured the velocity of movements in large arenas; high correlations were reported between vertical axis peak duration and the duration of locomotor play. The current study aimed to validate accelerometers for recording spontaneous locomotor play in calves' home pens over longer periods. Data were collected from 48 Holstein Friesian calves, housed in groups of 3 in pens of 10 m, at either 4 or 8 wk of age. Acceleration at the vertical axis of the hind leg was recorded at a rate of 1 Hz. One active time period for each calf was randomly selected (mean duration ± standard deviation = 34 ± 9 min). From video of the corresponding time period, the frequency of locomotor play events, consisting of run, turn, and buck/buck-kick, was recorded using behavior sampling. Combined counts of play events were highly correlated (Pearson r = 0.91) with counts of acceleration peaks. However, for calves with higher levels of locomotor play, this method underestimated the extent of play. Alternatively, run, turn, and buck events obtained from video were transformed by creating intervals of 10 s and then classifying each 10-s interval as comprising events of play ("play") or not comprising events of play ("no play"). The corresponding accelerometer data for all 10-s periods, equaling 10 consecutive readings each, were classified into play or no play by using quadratic discriminant analysis; 79% of periods with locomotor play were correctly classified. Counts of observed play intervals correlated with the counts of play periods from accelerometers (r = 0.87), but the discriminant analysis consistently overestimated play. In conclusion, accelerometer measurements at 1 Hz (in 1-s intervals) and at the vertical axis cannot be used alone to exactly quantify absolute levels of locomotor play in the home pen. However, counts of peak accelerations can provide a rough estimate of inter-individual differences in play events, and discriminant analysis can be used as a proxy for one-zero sampling of inter-individual differences in locomotor play.
玩耍行为是衡量奶牛犊牛福利的一个有前景的指标，因为它在负面情况下（如疼痛或饥饿）减少，而在积极情况下（如在适当的社交环境中）增加。直接测量玩耍行为非常耗时，因为它是不规则地进行的，并且在几天内可能不一致。为了方便自动记录玩耍行为，先前的研究将三轴加速度计安装在小牛的后腿上，并在大型竞技场中测量运动速度；报告称，垂直轴峰值持续时间与运动玩耍的持续时间之间存在高度相关性。本研究旨在验证加速度计在小牛的家庭畜栏中长时间记录自发运动玩耍的能力。数据来自 48 头荷斯坦弗里生小牛，在 10 米的畜栏中以 3 头一组饲养，年龄分别为 4 或 8 周。后腿垂直轴的加速度以 1 Hz 的速率记录。随机选择每头小牛的一个活跃时间段（平均持续时间±标准偏差=34±9 分钟）。从相应时间段的视频中，使用行为采样记录由奔跑、转弯和跳跃/跳跃踢组成的运动玩耍事件的频率。玩耍事件的综合计数与加速度峰值的计数高度相关（皮尔逊 r=0.91）。然而，对于运动玩耍水平较高的小牛，这种方法低估了玩耍的程度。或者，从视频中获得的奔跑、转弯和跳跃事件通过创建 10 秒的间隔来转换，然后将每个 10 秒的间隔分类为包含玩耍事件（“玩耍”）或不包含玩耍事件（“不玩耍”）。使用二次判别分析对所有 10 秒时间段（每个时间段包含 10 个连续读数）的相应加速度计数据进行分类为玩耍或不玩耍；79%的运动玩耍时间段被正确分类。观察到的玩耍间隔的计数与来自加速度计的玩耍时间段的计数相关（r=0.87），但判别分析一致地高估了玩耍。总之，1 Hz（在 1 秒间隔内）和垂直轴的加速度计测量不能单独用于精确量化家庭畜栏中运动玩耍的绝对水平。然而，加速度峰值的计数可以提供个体间玩耍事件差异的大致估计，判别分析可以用作个体间运动玩耍差异的零一采样的替代方法。
