Cows tend to stop eating when they get too hot, says University of Florida/IFAS professor Raluca Matieescu, which can affect their health and growth and threaten the longevity of the herd's food supply.
As climate change makes it harder to raise cattle, researchers are looking for ways to breed them better suited to hotter, longer summers.
Subtropical regions just north and south of this region are generally considered the hottest in the world, and heat stress in the region is a huge limiting factor, with reduced performance across the country resulting in an estimated $369 million (£291 million) worth of lost beef production per year.
Threats to food security
“Heat stress is the biggest threat to food security. Under heat stress, cattle growth, production and reproduction are affected,” Mateescu said.
Because cows lose 85 percent of their body heat through sweat, Mattieesk and his colleagues have been working to identify the genes of cow breeds that produce the sweatiest, heat-resistant offspring.
Their study, published in the Journal of Animal Science and Biotechnology, found that even within the same breed of cattle (in this case Brangus, a cross between a Brahman and an Angus), there are many differences: If we can select cattle to breed based on their ability to sweat, we can produce herds that can tolerate, grow, and thrive in hotter climates.
Growing concerns
“There are food security concerns because unless measures are taken that affect the ability of cattle to reproduce under heat stress, the cattle will not reproduce,” Matiesk added.
The study involved 2,401 Brangus cattle on two commercial ranches in Florida. Researchers used skin biopsies to identify phenotypes that contribute to an animal's ability to manage heat stress, such as sweat gland area, depth and length. Scientists genotyped all the animals and used software to estimate genetic parameters.
The study found that moderate variation in sweating ability is genetic, allowing farmers to select cattle that are more likely to sweat based on genetic markers. Both Brahman and Angus genes were found to have a positive effect on the sweating ability of Brangus cattle.
