Dairy cows are highly susceptible to extreme heat events, experiencing a decline in milk production and milk quality, poor nutrient absorption and an overall compromise in animal welfare. The reduced tolerance of dairy cows to heat stress in combination with climate change related changes in the frequency, duration and severity of heatwaves in Australian dairy regions suggest extreme heat events as one of the greatest risks to the dairy industry.
The Intergovernmental Panel of Climate Change (IPCC) defines extreme events as those as rare or rarer than the 10thor 90thpercentile. However, the definition of extreme events varies between industries. In dairy, extreme heat events are recognised as those greater than the preferred heat index threshold, the temperature humidity index (THI).
In this presentation, we will examine differences between extreme heat events in dairy when using the IPCC and dairy definitions. In addition, we will discuss challenges encountered while investigating and identifying extreme heat events in dairy scenarios, including whole-farm system models.