Abstract：
Dairy cattle are typically disbudded or dehorned. Little is known, however, about the biological function and role of horns during thermoregulatory processes in cattle, and thus about the potential physiological consequences of horn removal. Anecdotal evidence suggests that dairy cow horns increase in temperature during rumination, and few studies on other bovid species indicate that horns aid thermoregulation. The objective of this study was, therefore, to elucidate a possible thermoregulatory function of the horns in dairy cattle. Using non-invasive infrared thermography, we measured the superficial temperature of the horns, eyes, and ears of 18 focal cows on three different farms in a temperate climate zone under various environmental circumstances. Observations of social and non-social behaviours were conducted as well. Based on environmental temperature, humidity, and wind speed, the heat load index (HLI) was calculated as a measure of the heat load experienced by a cow. The temperature of the horns increased by 0.18 °C per unit HLI, indicating that horns serve the dissipation of heat. Dehorned cows had higher eye temperatures than horned cows, though this result should be interpreted with caution as the low sample size and experimental setup prevent casual conclusions. We did not, however, find changes in horn temperature during rumination, nor with any other behaviours. Our study thus supports a role of horns in thermoregulation, but not related to rumination. These results should be considered when assessing the potential consequences of horn removal, a painful procedure.
摘要：
奶牛通常被分散或去角。鲜为人知，然而,关于牛角在体温调节过程中的生物学功能和作用，因此，关于角移除的潜在生理后果。轶事证据表明，奶牛角在反观过程中温度升高，对其他牛科动物的研究很少表明角有助于体温调节。这项研究的目的是,因此,阐明奶牛牛角可能的体温调节功能。使用非侵入性红外热成像，我们测量了角的表面温度，眼睛,在不同的环境条件下，在温带气候区的三个不同农场的18头重点奶牛的耳朵。还进行了社会和非社会行为的观察。根据环境温度,湿度,湿度和风速，热负荷指数（HLI）是作为牛经历的热负荷的量度来计算的。角的温度每单位HLI增加0.18°C，表明喇叭起到散热的作用。去角牛的眼睛温度高于有角牛，尽管应谨慎解释此结果，因为样本量低和实验设置会阻止偶然的结论。我们没有,然而,发现喇叭温度在反光镜过程中的变化，也没有任何其他行为。因此，我们的研究支持角在体温调节中的作用，但与沉思无关。在评估拆除喇叭的潜在后果时，应考虑这些结果。一个痛苦的过程。
