WEST LAFAYETTE, Ind. - Heat and humidity are set to return to the eastern Corn Belt after weeks of unseasonably cool temperatures, meaning cattle producers need to be on the lookout for signs of heat stress in their herds.
Heat stress in cattle is a concern because it can reduce breeding efficiency, milk production, feed intake and weight gain. Extreme cases can be fatal, said Ron Lemenager, Purdue Extension beef specialist.
Heat stress affects all cattle, but hide color plays a role in determining which cattle might be more susceptible. Black-hided cattle absorb light, making them more prone to heat stress, whereas cattle with lighter colored hides, such as cream or red, might not become heat stressed as quickly.
"The good thing is that here in the eastern Corn Belt, we've actually had some pretty cool temperatures through the early part of the summer," Lemenager said. "We don't have the heat stress we had a year ago when we were experiencing the 2012 drought."
According to Lemenager, it usually takes a combination of high temperatures and high humidity to cause heat stress, but cattle also can experience heat stress in lower temperatures if humidity is high.
Cattle seeking shade is an early sign of heat stress. Having enough shade available is one key to prevention.
"The smaller the shade area, the worse the congregation of animals," Lemenager said. "That's probably not a good thing with cattle huddling together, obviously, because heat can be transferred from one animal to another."
Another risk is fly infestation. A high population of flies around a herd causes animals to huddle together more frequently. Flies can be managed with dust bags, insecticide-impregnated ear tags, insecticide sprays, pour-on insecticides or some combination of these.
Panting also can be a sign that cattle are heat stressed.
"They probably will have their tongues hanging out like a dog, and that panting is a way to get rid of some excess heat," Lemenager said.
Cattle standing in ponds or creeks also could be caused by heat stress.
In some cases, cattle can fall down or have convulsions. These are signs of severe heat stress, which can be fatal.
Lemenager recommended that producers make sure cool, fresh water is available to cattle at all times and use more shaded pastures during the warmer months. Sprinkling cattle with water also can help to dissipate heat, but it shouldn't be excessive. Producers also should be careful to keep cattle away from muddy areas, because hot mud could cause scalding where the skin comes in contact with hot mud.