Mayer D G, Davison T M, McGowan M R, Young B A, Matschoss A L, Hall A B, Goodwin P J, Jonsson N N, Gaughan J B
Queensland Beef Industry Institute, Department of Primary Industries.
Aust Vet J. 1999 Dec;77(12):804-8. doi: 10.1111/j.1751-0813.1999.tb12950.x.
To investigate the extent of heat load problems, caused by the combination of excessive temperature and humidity, in Holstein-Friesian cows in Australia. Also, to outline how milk production losses and consequent costs from this can be estimated and minimised.
Long-term meteorological data for Australia were analysed to determine the distribution of hot conditions over space and time. Fifteen dairy production regions were identified for higher-resolution data analysis. Both the raw meteorological data and their integration into a temperature-humidity thermal index were compiled onto a computer program. This mapping software displays the distribution of climatic patterns, both Australia-wide and within the selected dairying regions. Graphical displays of the variation in historical records for 200 locations in the 15 dairying regions are also available. As a separate study, production data from research stations, on-farm trials and milk factory records were statistically analysed and correlated with the climatic indices, to estimate production losses due to hot conditions.
Both milk yields and milk constituents declined with increases in the temperature-humidity index. The onset and rate of this decline are dependent on a number of factors, including location, level of production, adaptation, and management regime. These results have been integrated into a farm-level economic analysis for managers of dairy properties.
By considering the historical patterns of hot conditions over time and space, along with expected production losses, managers of dairy farms can now conduct an economic evaluation of investment strategies to alleviate heat loads. These strategies include the provision of sprinklers, shade structures, or combinations of these.
调查澳大利亚荷斯坦 - 弗里生奶牛因温度和湿度过高共同作用而导致的热负荷问题程度。同时，概述如何估算并尽量减少由此造成的产奶量损失及相应成本。
分析澳大利亚的长期气象数据，以确定炎热条件在空间和时间上的分布。确定了15个奶牛生产地区进行更高分辨率的数据分析。将原始气象数据及其整合到温度 - 湿度热指数中都编入一个计算机程序。这种绘图软件可显示全澳大利亚以及选定奶牛养殖区域内气候模式的分布。还可提供15个奶牛养殖区域中200个地点历史记录变化的图形展示。作为一项单独研究，对研究站、农场试验和牛奶加工厂记录中的生产数据进行统计分析，并与气候指数相关联，以估算炎热条件造成的生产损失。
随着温度 - 湿度指数的增加，牛奶产量和牛奶成分均下降。这种下降的起始和速率取决于多种因素，包括地点、生产水平、适应性和管理制度。这些结果已被纳入奶牛场管理者的农场层面经济分析中。
通过考虑炎热条件在时间和空间上的历史模式以及预期的生产损失，奶牛场管理者现在可以对减轻热负荷的投资策略进行经济评估。这些策略包括提供洒水装置、遮阳结构或两者结合。
