Raluca Mateescu

Dr. Raluca Mateescu of the University of Florida stands with Brahman cattle she’s studying for their heat tolerant traits.

Wearing black isn’t the best plan for staying cool on a hot summer day, so with Midwest temperatures rising, producers may be to reconsider their preference for black cattle. 

“Heat stress is a major limiting factor in beef production,” Dr. Raluca Mateescu said.

Mateescu has been studying cattle genetics and how it influences heat stress at the University of Florida. She spoke on thermotolerance June 19 at the Beef Improvement Federation conference in Brookings, South Dakota.

Heat stress can hurt the bottom line. Cattle that are too hot will eat less and sweat more, which means putting on fewer pounds.

Mateescu has been working to find a way cattle breeders can select genetic traits for tolerating heat while still breeding productive cattle. She studies a herd at the University of Florida with purebred Angus, purebred Brahman and a mix of hybrids of the two.

Brahman cattle are typically found in tropical or subtropical regions. They’re known for their loose skin, big ears and the hump over the back of their necks – all traits that help keep the animal cool.

Studying 335 heifers, researches on Mateescu’s team use vaginal sensors to monitor the cattle’s body temperature. They compare the readings with outside temperatures and humidity.

The team found that Brahman breeds were able to maintain a fairly steady body temperature up until the hottest hours of the day. The body temperature of purebred Angus heifers, however, started spiking by 9 a.m.

Angus benefitted some on cool nights. Their body temperature dipped lower than that of the Brahman heifers. But Angus cattle got hotter more quickly once daytime temperatures rose. Brahman temperatures stayed steadier.

“That seems a bigger advantage in having a constant temperature,” Mateescu said.

Several traits factor into heat tolerant cattle. She looks at their coat score by taking a hair sample and noting the length and diameter of the top and undercoat. She takes a small biopsy of the skin and studies the size of the sweat glands. Brahman have larger sweat glands and more of them.

“Just the size is a tremendous difference between the Angus and the Brahman,” she said.

Working with the Seminole Tribe of Florida, a large Brahman producer, she’s looking into more traits of the white cattle. She measures temperament, body condition and pregnancy rates – which can also be negatively influenced by heat stress.

She’s finding that Brahman can help improve a herd’s heat tolerance to some extent.

“They bring adaptability to our population, but not all Brhaman are the same,” she said. She’s hoping to learn how to identify traits that make them resistant to heat stress but create a cow that can still produce.

Reach Tri-State Neighbor Editor Janelle Atyeo at 605-335-7300, email jatyeo@tristateneighbor.com or follow on Twitter @JLNeighbor.

Janelle is editor of the Tri-State Neighbor, covering South Dakota, southwestern Minnesota, northwestern Iowa and northeastern Nebraska. Reach her at jatyeo@tristateneighbor.com or follow on Twitter @JLNeighbor


Janelle is editor of the Tri-State Neighbor, covering South Dakota, southwestern Minnesota, northwestern Iowa and northeastern Nebraska.