Valtorta S E, Leva P E, Gallardo M R
Agronomy and Veterinary School, National University of Littoral, Santa Fe, Argentina.
Int J Biometeorol. 1997 Nov;41(2):65-7. doi: 10.1007/s004840050055.
Two tree shades (TS1 and TS2) and an artificial shade structure (AS) were evaluated using black globe temperatures (BGTs) to assess their effectiveness in reducing heat load. The artificial structure consisted of a black woven polypropylene cloth providing 80% shade, mounted on 2.5-m-high eucalyptus posts. The work was carried out at Rafaela Experimental Station, Argentina, during the summer (January and February) 1994. BGTs and floor temperatures were measured in concrete floor holding pens with and without artificial shade. The results showed no difference between TS1, TS2 and AS, their average BGTs being 30.2 (SD 0.58), 29.0 (SD 0.70) and 30.2 (SD 0.74) degrees C, respectively. BGTs under all three shades were significantly lower (P < 0.01) than the average BGT recorded outside: 35.5 (SD 1.12) degrees C. Average BGTs in holding pens were 32.4 (SD 1.38) and 39.9 (SD 1.91) degrees C for shaded and non-shaded areas (P < 0.01). The corresponding average floor temperatures were 27.8 (SD 0.68) degrees C and 47.7 (SD 2.13) degrees C (P < 0.01). To assess the effects of shade on animal well-being, afternoon rectal temperatures (RT) and respiratory rate (respirations per minute, RR) of lactating cows were recorded twice a week. Rectal temperatures were significantly higher for non-shaded cows (P < 0.01), mean RT being 40.1 (SD 0.65) degrees C vs 39.3 (SD 0.42) degrees C for the shaded animals. Corresponding RRs were 78.9 (SD 18.0) and 60.7 (SD 10.6) (P < 0.05). It was concluded that: (1) tree and artificial shades produced similar effects, (2) shading the holding pen with an 80% shading cloth was effective in reducing heat load and floor temperatures, and (3) access to shade in our pasture-based system improved animal well-being.
使用黑球温度（BGT）对两种树荫（TS1和TS2）及一种人工遮阳结构（AS）进行了评估，以测定它们在降低热负荷方面的有效性。人工结构由一块提供80%遮荫率的黑色聚丙烯编织布组成，安装在2.5米高的桉木桩上。该研究于1994年夏季（1月和2月）在阿根廷拉费拉实验站开展。在有和没有人工遮阳的混凝土地面畜栏中测量了黑球温度和地面温度。结果显示TS1、TS2和AS之间没有差异，它们的平均黑球温度分别为30.2（标准差0.58）、29.0（标准差0.70）和30.2（标准差0.74）摄氏度。所有三种遮阳下的黑球温度均显著低于室外记录的平均黑球温度：35.5（标准差1.12）摄氏度（P < 0.01）。有遮阳和无遮阳区域畜栏中的平均黑球温度分别为32.4（标准差1.38）和39.9（标准差1.91）摄氏度（P < 0.01）。相应的平均地面温度分别为27.8（标准差0.68）摄氏度和47.7（标准差2.13）摄氏度（P < 0.01）。为评估遮阳对动物健康的影响，每周两次记录泌乳奶牛下午的直肠温度（RT）和呼吸频率（每分钟呼吸次数，RR）。无遮阳奶牛的直肠温度显著更高（P < 0.01），平均直肠温度为40.1（标准差0.6）摄氏度，而有遮阳动物的平均直肠温度为39.3（标准差0.42）摄氏度。相应的呼吸频率分别为78.9（标准差18.0）和60.7（标准差10.6）（P < 0.05）。得出的结论是：（1）树木遮阳和人工遮阳产生相似的效果；（2）用80%遮荫率的布料为畜栏遮阳能有效降低热负荷和地面温度；（3）在我们基于牧场的系统中，有遮阳条件可改善动物健康状况。
