Tips to Minimize Heat Stress
Cattlemen have options to help manage heat-related stress for their herds.
Don Spiers, environmental physiologist within the Department of Animal Science at the University of Missouri, says there are several management tips producers can use to keep cattle cool this summer.
The most helpful thing to do for cattle in hot weather is provide shade and plenty of fresh, clean water that is at a temperature lower than 80° F.
“If water sits in the sun getting hot, cattle won’t drink it,” Spiers cautions. “You need to shade not only the animals but also the water. If it’s cool, they’ll drink it, and this will help cool them.”
Cattle need at least 2 gallons (gal.) of water per 100 pounds (lb.) of body weight daily, Spiers advises. “This may need to be increased if it’s really hot.”
Reduce biting flies. Cattle expend energy trying to get rid of flies, which creates body heat, and they also tend to bunch up when fighting flies, he says. “If they bunch up, they don’t get much air flow over and around the body and will suffer more heat stress.”
In the feedlot, mounds soaked with water can help, he adds. The value of a mound is that it drains and won’t get muddy. The animals can lie on a cool surface, which helps them dissipate heat, and it’s even better if it’s shaded.
“We’ve measured the temperature of animals on plain earth versus grass. Open ground, in the same environment, heats up more and reflects more heat onto the animal than grass does. Anything that’s textured that will absorb solar radiation will reduce the amount of heat on the animal because there’s less reflected back,” he says.
Concrete is worse than soil, Spiers warns. “It absorbs more heat and holds onto it at night. If you have areas you can cool off with water or that are rough and can absorb solar heat and not reflect it back, this will help. If you can cool off concrete, it will stay cool for a period of time. If you have a way of wetting it in a shaded area, it will stay cool.”
Make sure cattle are exposed to the night sky if it’s a clear night, Spiers advises “Get them out from under the shade at night, and they will lose a lot of their heat to the night sky.” Nights will get cooler in an arid climate. The dry air has very low humidity, enabling the animals to lose heat through sweating and evaporation.
“When feeding cattle, feed toward the end of the day, so the heat of digestion doesn’t increase their body temperature in mid-day when it’s hottest. If you can give them more than 50% of their feed in the evening, when it’s starting to cool off, the heat of digestion won’t peak until several hours later. If it’s peaking around midnight they can lose that extra heat more readily than if you fed them a lot in the morning,” says Spiers.
Other feeding tips include reducing the amount of fiber in the diet, supplementing a little more energy and adding minerals, especially salt.
Don’t transport or work cattle in the heat, says Spiers. “Do it late in the day or very early in the morning. Don’t do anything with them at all in the middle of the day.”
Spiers encourages cattlemen to watch weather forecasts and use temperature-humidity indexes. The combination of air temperature and humidity is important in determining whether the current weather situation might be classified as in the alert stage, danger stage or emergency stage. His research developed a free app (Thermal Aid™) for android and Apple phones that does this calculation.
“The app automatically links to the closest weather station in your area. You put in basic information for your herd (whether they are on pasture or in a feedlot) and the app calculates the level of heat stress for the next few days. It uses a series of colors from green to red to display the level of heat stress your animals might experience. In addition, it provides suggestions for dealing with the heat,” says Spiers.
Sprinklers, chilled drinking water and fans are methods used with dairies, and some feedlots are utilizing these also. Research in Nebraska with feedlot cattle is looking at ways to promote more wind movement to cool the animals, without creating dust.
Editor’s Note: Heather Smith Thomas is a freelance writer and cattlewoman from Salmon, Idaho.