Johns Julia, Masneuf Sophie, Patt Antonia, Hillmann Edna
Faculty of Organic Agricultural Sciences, Farm Animal Behavior and Husbandry Section, University of Kassel, Witzenhausen, Germany.
Ethology and Animal Welfare Unit, Department of Environmental Systems Science, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland.
Front Vet Sci. 2017 Sep 29;4:153. doi: 10.3389/fvets.2017.00153. eCollection 2017.
In alpine regions, cows are often equipped with bells during pasture season to ensure that farmers can locate them. Constant exposure to the chime of a bell may affect cows' acoustic perception in general. The aim of this study is to test whether routine bell exposure affects the reactivity to a noise stimulus and might be associated with hearing impairment in cows. For the assessment, behavioral and cardiac indicators were used as indirect measures of hearing capacity. Cows that were either used to wearing a bell or not were exposed to a playback of low and high amplitude (=varying loudness). In addition, we tested whether wearing earplugs, mimicking hearing impairment, reduced the cows' reactivity toward the playback. On 24 farms, half of them routinely using cowbells, 96 Brown Swiss cows were tested in a 2 × 2 factorial cross-over design (65 or 85 dB, without or with earplugs) in a balanced order. The effects of bell experience, amplitude, and earplugs on the latency to the first behavioral and cardiac response to a 5-s playback were analyzed using linear mixed-effects models, considering dependencies within the data set. Cows reacted faster without earplugs and when they were exposed to 85 dB compared with 65 dB. The proportion of cows leaving the feeding rack after onset of the playback was reduced by bell experience and earplugs and was increased when exposed to 85 dB compared with 65 dB. Exposure without earplugs to 85 dB but not to 65 dB increased heart rate. Heart rate and heart rate variability indicated increased sympathetic activation during the exposure to 85 dB compared with 65 dB. In general, behavioral and cardiac indicators did not indicate severe hearing impairment due to routine bell exposure. The 85-dB stimulus increased arousal and avoidance compared with the 65-dB stimulus, with bell experience and earplugs leading to a general decrease in avoidance of the stimulus. This may reflect an altered acoustic perception of the playback stimulus in dairy cows that are routinely exposed to bells.
在高山地区，奶牛在放牧季节通常会佩戴铃铛，以确保农民能够找到它们。持续暴露在铃铛的叮当声中可能会总体上影响奶牛的听觉感知。本研究的目的是测试常规接触铃铛是否会影响奶牛对噪声刺激的反应性，以及是否可能与听力损伤有关。为了进行评估，行为和心脏指标被用作听力能力的间接测量方法。将佩戴铃铛与否的奶牛暴露于低振幅和高振幅（即不同响度）的声音回放中。此外，我们测试了佩戴模拟听力损伤的耳塞是否会降低奶牛对回放声音的反应性。在24个农场中，其中一半农场常规使用牛铃，96头瑞士褐牛按照平衡顺序以2×2析因交叉设计（65或85分贝，不戴或戴耳塞）进行测试。使用线性混合效应模型分析了铃铛经验、振幅和耳塞对5秒声音回放后首次行为和心脏反应潜伏期的影响，同时考虑了数据集中的相关性。与65分贝相比，不戴耳塞且暴露于85分贝时奶牛反应更快。声音回放开始后离开食槽的奶牛比例因铃铛经验和耳塞而降低，与65分贝相比，暴露于85分贝时该比例增加。不戴耳塞暴露于85分贝而非65分贝会使心率增加。与65分贝相比，暴露于85分贝期间心率和心率变异性表明交感神经激活增加。总体而言，行为和心脏指标并未表明常规接触铃铛会导致严重听力损伤。与65分贝的刺激相比，85分贝的刺激增加了觉醒和回避反应，铃铛经验和耳塞导致对刺激的回避总体减少。这可能反映了常规接触铃铛的奶牛对声音回放刺激的听觉感知发生了改变。
