5 July 2013

3 minute read

North America

K-State Extension interviews Larry Hollis, a Veterinarian at Kansas State University.

Soaring temperatures and humidity can take their toll on cattle in the Summer months, resulting in everything from reduced rates of gain to death and loss of cattle.

“Cattle will adapt to heat if it happens gradually, but that’s often not the case,” said Kansas State University veterinarian Larry Hollis, citing the quick wide temperature and humidity swings that can happen in the central High Plains.

“USDA has information including forecast maps that show geographically, where it expects the heat to cause problems,” said Hollis, who is a beef cattle veterinarian with K-State Research and Extension. See the maps at http://1.usa.gov/14KSLg2.

The website takes into account weather parameters that influence livestock comfort or stress, including temperature, wind speed, humidity and solar radiation. The site also includes a breathing equation that producers, feedlot managers and others can use to evaluate their animals.

“Cattle don’t have the ability to sweat like we do,” Hollis said. “Instead they’ll start panting.”

The USDA site has information to help producers gauge cattle heat stress by how many breaths an animal will take per minute. If an animal is taking less than 90 breaths per minute, the rate is considered “normal.” A rate of 90-110 breaths per minute indicates “alert,” 110-130 indicates “danger,” and above 130 breaths per minute indicates “emergency.”

“If you see them in the morning and they’re already over 100 breaths/minute, you know it will likely get worse as the day goes on,” Hollis said.

Beef cattle extension specialist Terry Mader and his colleagues at the University of Nebraska-Lincoln also have developed information that can be helpful to cattle producers. The extension publication is available at www.ianrpubs.unl.edu/; search for managing feedlot heat stress, publication number G1409.

“We can’t control the temperature or humidity, but we can control some things, Hollis said, as he outlined several steps.

• Provide cool drinking water. There is a difference between water heated by the sun all day and cool water.
• Make sure there is ample space around the drinking source, so cattle don’t bunch up as they are accessing the water.
• Provide shade – whether it is moving animals to a different pasture with more trees or stretching a screen over pens.
• Remove anything that impedes airflow. Do not pen cattle near windbreaks. Mow weeds if they are tall enough to function as a windbreak. If there are mounds, cattle will use them to try to catch a breeze.
• Control flies. Cattle will come together to help each other deflect flies but air circulation is impeded when they bunch up, so controlling flies helps with controlling heat stress.
• If handling cattle, do it early in the day. Have all work done by 10 a.m.
• Where possible, use sprinklers, but do not use mist. Mist raises humidity, which adds to stress. Instead, use a system that dispenses large droplets.

“Some operations have what looks like large water cannons and some fire departments will come out and help soak the cattle,” Hollis said. He noted, however, that fire equipment and powerful hoses can be extremely frightening to the animals.

“If you’re going to put water on them, do it right or don’t do it,” he said, adding that the goal is to soak the cattle, not lightly mist.

“At the end of the day, cattle that are not alive don’t do us much good. When we have performance losses, that’s one thing, but when your animals don’t survive, that’s not a good situation at all,” Hollis said.