不同温湿指数环境下奶牛阴道温度的变化规律

为探究不同温湿指数(THI)环境下奶牛阴道温度的变化规律,试验分别在高THI(78.5±3.2)、中THI(70.4±4.1)、低THI(56.3±5.5)环境下连续7d监测15头健康妊娠奶牛的阴道温度及所在牛舍内外的温度和相对湿度。结果表明:高THI环境下奶牛平均阴道温度、日极值均差、测期极值差极显著高于中、低THI环境下奶牛相应的测值(P<0.01);奶牛日平均阴道温度和日平均THI、日最高阴道温度和日受热时长的相关系数r分别是0.811、0.896(P<0.01);引起日平均阴道温度、日最高阴道温度开始快速升高的日平均THI、日最大THI分别为71.4、77.3,日受热时长为10.6h时日最高阴道温度变化出现拐点。由此可见,高THI环境下奶牛阴道温度变化幅度大;相比THI,日受热时长会影响奶牛阴道温度的变化。

Variation of Vaginal Temperature under Different Temperature-humidity Index in Dairy Cows

This study was to investigate variation of dairy cows vaginal temperature(VT) under the different temperaturehumidity index(THI) and the effect of THI on the VT of dairy cows. Continuous measurements were conducted to obtain VT of 15 healthy pregnant cows and cowshed temperature and relative humidity in different THI environment(78.5±3.2,70.4±4.1, 56.3±5.5) each for 7 days. The result showed that average value, average difference of daily extreme value and extreme difference of measuring period for VT of cows in high THI environment was significantly higher than those of cows in medium and low THI environments. There were significant correlations(P<0.01) between daily average VT and daily average THI(r=0.811), daily maximum VT and daily heat stress period(r=0.896). The daily average THI and daily maximum THI that caused the average VT and the highest VT to rise rapidly were 71.4, 77.3, respectively. When heat stress exposure time is 10.6 h, the maximum VT changes have an inflection point. It can be concluded that the VT of dairy cows in a high THI environment varies greatly. Compared with THI, heat stress exposure time can reflect the change of the VT of dairy cows.