北京市气候变化对奶牛热冷应激的影响

Impact of climate change on heat and cold stress of cow breeding in Beijing

气候变化对奶牛养殖的影响日益凸显,一些地区奶牛养殖的热应激或冷应激外部环境有所加剧。该文采用温湿度指数(temperature humidity index,THI)和风寒温度(wind chill temperature,WCT)2个指标,分析了北京地区1951-2012年逐日的THI和WCT的变化特征,重点分析了气候变化对奶牛养殖应激环境变化规律的影响。结果表明:近62a来北京地区温度提升了1.93℃,气候变暖特征明显快于全国,气候变化加剧了北京地区热应激温度环境,降低了冷应激温度环境,综合考虑相对湿度和风速等气象因素,气候变化对北京地区热应激综合环境影响小,对冷应激综合环境影响大。但值得关注的是,2008年以来,北京地区热冷应激环境呈现"双升"态势,尤其冷应激环境明显增强,2012年冷应激天数为近10a来最高,对北京地区的奶产量产生了不利影响。研究结论对以开放或半开放式牛舍养殖为主的北京地区的牛舍改造和应激设施设备改善提供了科学决策依据。

The impact of climate change on cow breeding has become increasingly prominent, and in some areas the external environment of heat stress or cold stress increased. This research adopts two indicators-the temperature and humidity index （THI） and wind chill temperature （WCT）, analyses the daily change characteristics of THI and WCT in Beijing from 1951 to 2012, focusing on the analysis of the influence of variation of stress environment of cow breeding to climate change. The study showed that：1） Over the past 60 years, the temperature of Beijing increased 1.93℃. Not only the annual rainfall, but also the relative humidity decreased significantly in Beijing from the new century. The average annual relative humidity was only 50% from 2010 to 2011, which declined 10 percent compared with 1951-1959. According with the national climate change trend, the climate change of Beijing showed the typical characteristics of warm and dry. 2）Just from the temperature environment, climate change of Beijing resulted in the number of days markedly increasing that maximum temperature more than 32℃, and the number of days obviously decreasing that minimum temperature less than -5℃. The number of days that the maximum temperature was more than 32℃ added 11 days from 2000 to 2012 compared to 1950-1959, while the number of days that the minimum temperature was less than -5℃ was reduced by 28 days. In other words, climate change has exacerbated the heat stress temperature environment of cow breeding in Beijing and improved cold stress temperature environment from the view of the absolute temperature. 3） From the THI, although the number of days that the maximum temperature was more than 32℃ obviously raised from the new century, the climate change of warm and dry did not significantly increase the degree of heat stress in cow breeding, which was due to the observably decreased relative humidity. From the WCI, the number of days were reduced in which the wind-chill index was less than or equal to -10, along with the significantly reduced number of days that the minimum temperature was less than -5℃. The degree of cold stress evidently lightened in Beijing, but it was still mild cold stress mainly in cow breeding. This research still reminds us that the cold and heat stress environment presented the situation of ＂Double Ascending＂ in Beijing since 2008, especially the cold stress environment significantly increased.