Tips for Managing Heat Stress
A Kansas State University veterinarian is urging cattle producers to beef up their plans for managing heat stress in their herds, a challenge that costs the U.S. cattle industry up to $370 million in losses each year. A.J. Tarpoff, a beef veterinarian with K-State Research and Extension, said cattle are resilient animals; they will often acclimate to hot temperatures. But an accumulation of factors – including humidity, solar radiation, the color of their hide, diet and more – can drastically change a cow’s ability to withstand summer’s heat. “It really is a multi-layer challenge,” Tarpoff said. “Each animal within a group or pen is not affected the same way. Animals with higher body condition scores, or with darker hides, or finisher steers and heifers that are getting ready to go to harvest are at higher risk of heat stress.” Tarpoff said heat stress decreases the reproductive efficiency and performance of cattle grazing on pasture. In confined facilities, heat stress often causes cattle to eat less, which also negatively affects their performance. The human body cools itself on a hot day by sweating, called evaporative cooling. But Tarpoff notes that cattle sweat only 10 percent as much as humans, and panting is their primary way of dissipating heat. “As temperatures rise and their heat load in creases, they will start breathing faster,” he said. “They are dissipating heat through tiny droplets in the respiratory tract.” Doing so, however, causes cows to eat less, setting them on a path to poor growth and future performance. “This all has to do with heat load,” Tarpoff said. “The internal temperature of cattle will peak two hours after the hottest point of the day. So, our strategy for keeping cows cool needs to be built around knowing that.”
