Furukawa Eri, Ozawa Tomomi, Higaki Shogo, Suda Tomoko, Sasaki Yosuke, Murayama Kyotaro, Noguchi Michiko, Yoshioka Koji
National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki 305-0856, Japan.
Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706.
JDS Commun. 2024 Mar 2;5(4):332-337. doi: 10.3168/jdsc.2023-0515. eCollection 2024 Jul.
This study aimed to determine the applicability of a tail-attached device in monitoring animal-based indicators (ABI) associated with changes in environmental conditions in calves through investigating the relationship between sensor-derived ABI and the temperature-humidity index (THI). Furthermore, to identify effective ABI indicative of heat stress status, sensor-derived ABI of calves under differing heat stress levels based on rectal temperature (RT) were compared. The tail-attached device, which is capable of measuring skin temperature (ST), activity intensity, and roll angle along the longitudinal axis of the tail at 3-min intervals, was attached to 99 preweaning female Holstein calves for an average of 4 wk (26.4 ± 6.8 d). After selecting data from mild to hot days (daily average THI of ≥55), physiological (daily maximum tail ST) and behavioral (daily average activity intensity, daily total lying time, and daily total body position change) ABI were computed, and their relationship with the daily average THI was determined using piecewise regression analysis. Additionally, during the hot season, RT of 20 randomly selected tested calves were measured thrice a week (every 2.4 ± 0.5 d), and a comparison was conducted between the ABI of calves with normal RT (<39.5°C) and those with high RT (≥39.5°C), utilizing data from days characterized by potential heat stress (daily average THI of ≥75). During the study, ambient temperature (°C) and relative humidity (%) were recorded every 10 min using an automatic digital data logger, from which the daily average THI was calculated. Piecewise regression analysis identified THI breakpoints of 73.6 for tail ST, 79.1 for average activity intensity, 72.3 for lying time, and 79.1 for position change. All the tested ABI tended to increase as THI increased, and this trend was pronounced in tail ST, activity intensity, and position change after the breakpoint. These 3 ABI were higher in calves with high RT compared with those with normal RT, whereas lying time shared similar values between the RT groups. Overall, these findings suggest that the tail-attached device can simultaneously monitor both physiological and behavioral ABI in calves, and among the ABI, tail ST, activity intensity, and position change are the effective ABI indicative of heat stress status.
本研究旨在通过调查传感器衍生的动物基础指标（ABI）与温湿度指数（THI）之间的关系，确定一种尾部附着装置在监测与犊牛环境条件变化相关的ABI方面的适用性。此外，为了确定指示热应激状态的有效ABI，比较了基于直肠温度（RT）处于不同热应激水平下犊牛的传感器衍生ABI。将能够每隔3分钟测量皮肤温度（ST）、活动强度和沿尾巴纵轴的滚动角度的尾部附着装置，安装在99头断奶前的雌性荷斯坦犊牛身上，平均安装4周（26.4±6.8天）。在从温和到炎热的日子（每日平均THI≥55）中选取数据后，计算生理（每日最大尾部ST）和行为（每日平均活动强度、每日总躺卧时间和每日全身位置变化）ABI，并使用分段回归分析确定它们与每日平均THI的关系。此外，在炎热季节，每周三次（每2.4±0.5天）测量20头随机选择的受试犊牛的RT，并利用潜在热应激日（每日平均THI≥75）的数据，对RT正常（<39.5°C）和RT高（≥39.5°C）的犊牛的ABI进行比较。在研究期间，使用自动数字数据记录器每10分钟记录一次环境温度（°C）和相对湿度（%），并据此计算每日平均THI。分段回归分析确定尾部ST的THI断点为73.6，平均活动强度为79.1，躺卧时间为72.3，位置变化为79.1。所有测试的ABI都倾向于随着THI的增加而增加，并且在断点之后，这种趋势在尾部ST、活动强度和位置变化中更为明显。与RT正常的犊牛相比，RT高的犊牛的这3种ABI更高，而躺卧时间在RT组之间的值相似。总体而言，这些发现表明，尾部附着装置可以同时监测犊牛的生理和行为ABI，并且在ABI中，尾部ST、活动强度和位置变化是指示热应激状态的有效ABI。
