Scasta John Derek
Department of Ecosystem Science, University of Wyoming, Laramie, WY 82071, USA.
Animals (Basel). 2021 Apr 21;11(5):1186. doi: 10.3390/ani11051186.
Cattle in high-elevation rangelands experience cold and hot extremes. Given the increase in black hided cattle globally, thermoregulation options on rangelands, and hide color function affecting mammal thermal ecology, this study quantified winter albedo, external cattle temperatures (Temp), and differences (ΔT) between Temp and ambient air temperature (Temp), for different color cattle along a thermal gradient (≈-33 °C to +33 °C). From 2016 to 2018, I measured 638 individual Temp × Temp combinations for white ( = 183), red ( = 158), and black ( = 297) female cattle free roaming extensive Wyoming, USA rangelands. Pixel brightness of cow images relative to snow indicated mean (±standard error) albedo for white, red, and black cows ( = 3 of each) was 0.69 (±0.15), 0.16 (±0.04), and 0.04 (±0.01), respectively ( = 0.0027). Temp was explained by Temp (+), clear sky insolation index (+), and cow albedo (-). However, ΔT was explained by Temp (-), long-wave radiation (infrared; Rad (-)), Temp (+), and cow albedo (+). Temp relative to ΔT was correlated for all hide colors (all -values < 0.0001; all values > 0.7)), yet slopes () were ~2× greater for red and black cows than white cows.
高海拔牧场的牛会经历极寒和酷热天气。鉴于全球黑色皮毛牛的数量增加，牧场的体温调节选择以及影响哺乳动物热生态的皮毛颜色功能，本研究对不同颜色的牛沿着热梯度（约-33°C至+33°C）的冬季反照率、体表温度（Temp）以及体表温度与环境气温（Temp）之间的差异（ΔT）进行了量化。2016年至2018年期间，我在美国怀俄明州广阔的牧场中，对自由放养的638头白色（n = 183）、红色（n = 158）和黑色（n = 297）雌性牛的Temp×Temp组合进行了测量。奶牛图像相对于雪地的像素亮度表明，白色、红色和黑色奶牛（每种颜色各3头）的平均（±标准误差）反照率分别为0.69（±0.15）、0.16（±0.04）和0.04（±0.01）（P = 0.0027）。体表温度受环境气温（+）、晴空日照指数（+）和奶牛反照率（-）的影响。然而，体表温度与环境气温的差异受环境气温（-）、长波辐射（红外线；Rad（-））、体表温度（+）和奶牛反照率（+）的影响。所有皮毛颜色的体表温度与体表温度和环境气温差异之间均存在相关性（所有P值<0.0001；所有R值>0.7），但红色和黑色奶牛的斜率（β）约为白色奶牛的2倍。
