Center for Animal Welfare, Department of Animal Science, University of California, Davis 95616; Animal Behavior Graduate Group, University of California, Davis 95616.
Center for Animal Welfare, Department of Animal Science, University of California, Davis 95616; AgroSup Dijon, 21000 Dijon, France.
J Dairy Sci. 2021 Aug;104(8):9185-9194. doi: 10.3168/jds.2020-20112. Epub 2021 May 28.
Oral behaviors, including feeding, drinking, grooming, and non-nutritive behaviors, are used as indicators of health and welfare in dairy calves, but continuous measurement of these behaviors can be labor intensive. Instantaneous sampling is often used to save labor but has only been validated for feeding behavior in calves. One-zero sampling may be an appropriate strategy well suited to capturing the rapid performance of non-nutritive behaviors. Our objective was to validate 1-0 and instantaneous sampling for measurement of oral behaviors around the time of bottle delivery against true values. Eleven Holstein heifer calves were housed individually, provided water, and fed a diet of starter grain and milk replacer (4.8-5.6 L/d step-up) via a bottle. When calves were 23 ± 7 d old, they were video recorded for 30 min before and after the morning 2.5 ± 0.2 L milk meal, from approximately 0900 to 1000 h. We measured ruminating, eating, drinking water, sucking milk, grooming, non-nutritive oral manipulation, and tongue flicks continuously and with instantaneous and 1-0 sampling at 5-, 10-, 30-, and 60-s intervals. We also examined the effect of instantaneous timing within these intervals. Estimates obtained through subsampling were compared with true values via regression analysis. The subsampling interval was determined to represent true values if the coefficient of determination ≥0.9, slope = 1, intercept = 0, and relative error <10%. Ruminating, drinking water, and eating were not performed by all 11 calves and were not included in the analysis. The proportions of time performing non-nutritive oral manipulation, grooming, and tongue flicks generated by continuous and 1-0 sampling were highly correlated but were consistently overestimated by 1-0 sampling, especially as calves spent more time engaged in these behaviors. Sucking milk was accurately represented at intervals of less than 30 s, likely due to most sucking bouts continuing for at least 150 s at a time and low between-calf variability compared with the other behaviors. Different start times within a given instantaneous interval resulted in wide variance in discrepancies between subsampling and continuous recording for all behaviors. We conclude that around milk feeding, 1-0 sampling is an appropriate choice to represent stimulus-elicited behavior, such as sucking milk in a milk-restricted system. However, time engaged in short, highly variable, or intermittent behaviors is not reliably captured via instantaneous or 1-0 sampling in the hour around bottle delivery.
口腔行为，包括进食、饮水、理毛和非营养性口腔行为，被用作奶牛犊牛健康和福利的指标，但这些行为的连续测量可能需要大量的劳动力。瞬时采样通常用于节省劳动力，但仅在犊牛的进食行为中得到验证。零一采样可能是一种合适的策略，非常适合捕捉非营养性行为的快速表现。我们的目的是验证在奶瓶喂养前后，1-0 和瞬时采样对口腔行为的测量值与真实值的吻合度。11 头荷斯坦小母牛单独饲养，提供水，并通过奶瓶喂食开食料和代乳料（4.8-5.6 L/d 逐渐增加）。当犊牛 23 ± 7 日龄时，从大约 0900 到 1000 小时，在上午 2.5 ± 0.2 L 牛奶餐前后进行 30 分钟的视频记录。我们连续并以 5、10、30 和 60 秒的间隔进行瞬时和 1-0 采样，测量反刍、进食、饮水、吮吸牛奶、理毛、非营养性口腔操作和舌弹。我们还检查了这些间隔内瞬时时间的影响。通过子采样获得的估计值通过回归分析与真实值进行比较。如果决定系数≥0.9、斜率=1、截距=0 和相对误差<10%，则子采样间隔表示真实值。反刍、饮水和进食并不是所有 11 头小牛都进行的，因此未包含在分析中。通过连续和 1-0 采样生成的非营养性口腔操作、理毛和舌弹的时间比例高度相关，但 1-0 采样始终高估，尤其是当小牛更多地参与这些行为时。吮吸牛奶在小于 30 秒的间隔内准确表示，这可能是因为大多数吮吸回合一次持续至少 150 秒，并且与其他行为相比，小牛之间的变异性较低。在给定的瞬时间隔内的不同开始时间会导致所有行为的子采样和连续记录之间的差异出现很大差异。我们得出结论，在接近喂奶时，1-0 采样是代表受刺激的行为（例如在牛奶受限系统中吮吸牛奶）的合适选择。然而，在接近奶瓶喂养的 1 小时内，通过瞬时或 1-0 采样无法可靠地捕捉到短时间、高度可变或间歇性行为所花费的时间。
