Spain J N, Spiers D E
Department of Animal Sciences, University of Missouri, Columbia 62511, USA.
J Dairy Sci. 1996 Apr;79(4):639-46. doi: 10.3168/jds.S0022-0302(96)76409-3.
Holstein (n = 12) and Guernsey (n = 6) calves, housed in hutches, were used to evaluate the complex relationships among external environment, housing microclimate, and thermal status of calves. The study was conducted during the summer; 9 calves were housed in hutches under supplemental shade, and 9 calves were maintained in hutches under direct sunlight. Environmental and calf temperatures were measured twice daily at 0700 and 1500 h, which included determinations of air temperature, inner and outer surface temperatures of the hutch, rectal and skin temperatures of the calf, and respiration rate. Outer and inner surface temperatures of the hutch were lower under supplemental shade. Hutch air temperature was highly correlated with inner surface temperature and therefore was lower in the shaded environment. During the p.m. period, when heat stress was highest, calves housed in a shaded hutch environment had lower skin temperatures and respiration rates than did unshaded calves. Body temperature and respiration rates increased less for calves in shade than for calves in sun. These data define the relationship between the calf and the environment. Supplemental shade diminished the severity of heat stress experienced by calves that were housed in hutches during the summer.
选用圈养在畜栏中的12头荷斯坦犊牛和6头根西犊牛，来评估犊牛的外部环境、畜栏小气候和热状态之间的复杂关系。研究在夏季进行；9头犊牛圈养在有额外遮荫的畜栏中，9头犊牛圈养在阳光直射的畜栏中。每天07:00和15:00测量环境温度和犊牛体温两次，测量内容包括气温、畜栏内外表面温度、犊牛直肠温度和皮肤温度以及呼吸频率。有额外遮荫时，畜栏外表面和内表面温度较低。畜栏空气温度与内表面温度高度相关，因此在有遮荫的环境中较低。在下午热应激最高的时段，圈养在有遮荫畜栏环境中的犊牛皮肤温度和呼吸频率低于无遮荫的犊牛。遮荫环境中犊牛的体温和呼吸频率增幅小于阳光下的犊牛。这些数据确定了犊牛与环境之间的关系。额外遮荫减轻了夏季圈养在畜栏中的犊牛所经历的热应激严重程度。
