Igono M O, Bjotvedt G, Sanford-Crane H T
Division of Biosciences, Arizona State University, Tempe 85287-0608.
Int J Biometeorol. 1992 May;36(2):77-87. doi: 10.1007/BF01208917.
The environmental profile of central Arizona is quantitatively described using meteorological data between 1971 and 1986. Utilizing ambient temperature criteria of hours per day less than 21 degrees C, between 21 and 27 degrees C, and more than 27 degrees C, the environmental profile of central Arizona consists of varying levels of thermoneutral and heat stress periods. Milk production data from two commercial dairy farms from March 1990 to February 1991 were used to evaluate the seasonal effects identified in the environmental profile. Overall, milk production is lower during heat stress compared to thermoneutral periods. During heat stress, the cool period of hours per day with temperature less than 21 degrees C provides a margin of safety to reduce the effects of heat stress on decreased milk production. Using minimum, mean and maximum ambient temperatures, the upper critical temperatures for milk production are 21, 27 and 32 degrees C, respectively. Using the temperature-humidity index as the thermal environment indicator, the critical values for minimum, mean and maximum THI are 64, 72 and 76, respectively.
利用1971年至1986年的气象数据对亚利桑那州中部的环境特征进行了定量描述。根据每天低于21摄氏度、21至27摄氏度以及高于27摄氏度的时长等环境温度标准，亚利桑那州中部的环境特征包括不同程度的热中性期和热应激期。利用1990年3月至1991年2月两个商业奶牛场的产奶数据来评估环境特征中确定的季节效应。总体而言，与热中性期相比，热应激期间的产奶量较低。在热应激期间，每天温度低于21摄氏度的凉爽时段为减轻热应激对产奶量下降的影响提供了安全边际。使用最低、平均和最高环境温度，产奶的上限临界温度分别为21、27和32摄氏度。使用温度湿度指数作为热环境指标，最低、平均和最高温湿指数的临界值分别为64、72和76。
