Temperatures are soaring and cattle are stressing.
Although there have been no reports of large death losses, the heat reduces feed efficiency and daily gains, both on pastures and feedlots.
“The really high temperatures we’ve had the last several weeks have caused cattle to undergo a lot of heat stress,” said Dr. Joe Paschal, AgriLife Extension livestock specialist, Corpus Christi. “Typically, cattle are going to shade up a lot more, particularly if they are black-hided rather than if they are of Bos indicus or Brahman influence.”
Paschal said in addition to staying in the shade much of the day rather than grazing, cattle are going to look for ways to cool off, such as standing in ponds or stock-water tanks.
If these measures aren’t enough, then they will start showing physiological signs of heat stress, he said. Cattle mainly cool themselves by panting. Bringing in cool, moist air will allow them to lower their core temperature, and in turn, their outer body by increasing the amount of blood to their hides.
“If they can bring cool air into their lungs, that’s fine, but they can’t now,” Paschal said. “They are bringing in air that’s at 100 degrees and at very low humidity, and it’s making them even hotter. This affects their entire metabolic process. It’s even harder on feedlot cattle as they’re fatter.”
Dr. Ted McCollum, AgriLife Extension beef cattle specialist, Amarillo, said it is true that feedlot cattle are more susceptible to heat stress. This is because they are generally fatter or “fleshier,” and the fat acts as an insulator, making it harder for them to dispel heat by convection.
However, he hasn’t heard that many reports on death loss this summer, he said.
Of the 120 or so feedlots that finish cattle in Texas, Oklahoma and eastern New Mexico, most are in the Texas Panhandle, McCollum said. And one of the several reasons that most confined cattle feeding units are there is because of the climate.
“The one thing about this part of Texas as compared to South Texas, or farther north in Nebraska where you hear about death losses from heat stress in feedyard cattle, is that we do cool down at night,” McCollum said.
The cooler nighttime air means cattle in Panhandle feedyards have the chance to “unload” that heat at night.
This isn’t to say that some cattle in Panhandle feedyards haven’t suffered health problems during the past several weeks, but to his knowledge there haven’t been any large-scale problems, he said.
Some performance losses have occurred because of reduced feed consumption during the hot weather. Digestive processes generate body heat. So in response to hot ambient temperatures, cattle will often reduce feed intake in an effort to reduce their heat load, he said.