Hot And Cold Cattle: Developing Cattle-Specific Thermal Stress Forecast Products

Hot And Cold Cattle: Developing Cattle-Specific Thermal Stress Forecast Products

Weather extremes, such as winter chill events, heavy rainfall, flooding, and protracted heat
can cause discomfort and harm in grazing cattle and livestock in exposed pastures. If the
conditions are severe enough, as was the case during the Gulf floods of February 2019,
animals can die from hypo- or hyper-thermia. Currently, the Bureau of Meteorology
generates a national sheep graziers alert if there is the potential for chill and exposure,
however there is no national warning system or forecast product for heat or cold stress in
cattle.
In this presentation, I will discuss the current research that is being conducted, as part of the
Northern Australia Climate Program (NACP), on developing forecast products that have been
specifically designed for predicting cattle comfort during both hot and cold weather
conditions. I will first discuss three different cattle heat stress indices, using past historical
heat events to show the types of weather conditions that animals are most susceptible to (for
example, humid and sunny).
I will then present a new seven-day cattle heat stress forecast product that is under
development; these forecasts display the hourly evolution of accumulated heat load potential
in cattle for different breed-specific heat-tolerance thresholds. Future work aims to extend
cattle heat stress forecasts out to 2–3 weeks using the Bureau's sub-seasonal forecast
model, ACCESS-S2. Finally, I will present the latest NACP research on constructing new
cold thresholds for cattle in northern Australia, based on a comparison of the livestock chill
index and the cattle comfort index, utilising historic chill events for ground-truthing