Overheating cattle: more and more dangerous heat is coming for northern Australia’s herds
Cattle can only cope with so much heat – and more is coming. Graziers will have to install shade – and muster at dawn.
More and more dangerous heat is coming for northern Australia's herds of cattle. The country is one of the world's biggest consumers of red meat, with the average Australian eating about 22 kilos of beef in 2024. However, with Australia already 1.5°C warmer than in 1910 and continuing to warm, concerns are arising over the future of cattle herds in the region.
Cattle are built to produce heat, not lose it, through fermentation in their stomachs. They have limited cooling mechanisms compared to humans, relying on panting, seeking shade, or waiting for cooler nights. British breeds from cool European climates are especially vulnerable to heat stress. Research has found that dangerous levels of heat will arrive more frequently, posing particular problems for British cattle breeds from the Bos taurus subspecies.
To protect cattle from the extra heat, building more shade structures could be a solution. Tropical breeds such as Brahmans are more resilient but not immune. Climate models were used to compare heat levels from the 1990-2010 period with those expected in the 2050s and 2090s under both low- and high-emissions futures. The Heat Load Index was used to estimate how much heat cattle are accumulating, highlighting the impact of breed differences.
British breeds such as Angus and Hereford reach their heat threshold at a value of 86, while tropical breeds like Brahman can tolerate up to 96 without accumulating more heat than they can dissipate. Currently, most northern graziers rely on Brahman or Brahman-cross breeds. However, for British breeds, dangerous heat days are projected to rise significantly from 117 days now to 143 by the 2050s (low emissions) and as high as 195 days a year by the 2090s (high emissions). In some semi-arid regions, these days could reach over 300 annually.
The effects of heat stress on cattle include reduced feed intake, slower weight gain, delayed market readiness, and decreased fertility. Dark-cutting beef, produced under intense heat, is less valuable. Cattle also struggle with hotter nights, which add to their strain.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
