The evaluation of risk and hazard map of hot environment for dairy cows on the effects of climate change

我们试图通过气象数据来估计牛奶量的减少，以便用THI（温湿度指数）来评估牛棚的实际情况。由于热胁迫不会立即产生影响，因此我们采用THI指数的20天移动平均值进行评价。THI的值超过71意味着奶量的减少。在1994年炎热的天气，THI显示超过71之间的7月初和9月底在日本西部地区。1993年凉爽的夏天也出现了这种情况。1994年熊本市产奶量下降的原因为每头牛278 kg，西日本地区产奶量高，而北海道地区产奶量低。因此，热环境一步的成本估计在每头牛三万日元左右。另一方面，我们还调查了去年夏季通常进行细雾冷却期间牛表面的实际潮湿状况。该方法是采取热示踪照片的潮湿条件下，在牛的表面和测量像素数的基础上的表面温度的差异。在我们牛舍的细雾冷却系统中，湿牛表面积很小，易湿的一侧为40- 50%，难湿的一侧不到10%，湿牛表面积总共约占所有牛表面积的30%。

We tried to estimate the decrease of milk volume used by the meteorological data in order to evaluate its actual condition with THI (Temperature-Humidity Index) at a cattle shed. We evaluated to use the values of 20 days moving average of THI index, because the heat stress doesn't affect immediately. A value of THI exceeds more than 71 means the decrease of the milk volume. In hot weather 1994, THI was shown more than 71 between the beginning of July and the end of September in western Japan region. This pattern was also shown in cool summer 1993. The account of the decrease of milk yield in 1994 period was 278 kg per cattle in the case of Kumamoto city, and it was shown high values in western Japan region, while low values in Hokkaido area. Therefore, the estimation of the cost for a step of the hot environment was about thirty thousand yen per cattle. On the other hand, we also investigated the actual wet condition at a cattle surface in the period that fine mist cooling was generally conducted in summer season in last year. The method was to take thermo tracer pictures of wet condition at a cattle surface and to measure the pixel number based on the difference of the surface temperature. In the case of fine mist cooling system at our cattle shed, the wet cattle surface area was small; the side that was easy to get wet was 40-50%, difficult to get wet was less than 10%, and wet cattle surface area altogether was about 30% of all cattle surface area.