du Preez J H, Giesecke W H, Hattingh P J, Eisenberg B E
Veterinary Research Institute, Onderstepoort, Republic of South Africa.
Onderstepoort J Vet Res. 1990 Sep;57(3):183-7.
November-March are the hottest months of the year with the highest monthly mean "temperature-humidity index" (THI) in South Africa and Namibia. These 5 months are associated with severe heat stress in dairy cattle, are of critical importance for their performance and may have great economic implications for the owner as well as for the dairy industry. Firstly, compared with the existing Livestock Weather Safety index (LWSI), more relevant meteorological data can be generated when mapping South Africa and Namibia according to the LWSI modified for lactating dairy cattle (LDC). Secondly, compared with the observed true THI values alone, more relevant data on heat stress and its deleterious effects on dairy cattle performance, become available when mapping South Africa and Namibia according to the combined observed true and predicted THI values. Minimum precautions against heat stress in dairy cattle are recommended depending on THI values as classified by the LWSI for LDC.
11月至次年3月是南非和纳米比亚一年中最热的月份，月平均“温度-湿度指数”（THI）最高。这5个月与奶牛的严重热应激相关，对奶牛的生产性能至关重要，可能对奶牛场主以及乳制品行业产生重大经济影响。首先，与现有的家畜天气安全指数（LWSI）相比，根据为泌乳奶牛（LDC）修改后的LWSI对南非和纳米比亚进行地图绘制时，可以生成更相关的气象数据。其次，与仅观察到的真实THI值相比，根据观察到的真实THI值和预测的THI值相结合对南非和纳米比亚进行地图绘制时，可以获得更多关于热应激及其对奶牛生产性能有害影响的相关数据。建议根据LWSI为LDC分类的THI值采取最低限度的奶牛热应激预防措施。
