July 27, 2007

When temperatures are forecast to hit 90°F and above, cattle producers need to take steps to ward off heat stress in their herds, a University of Nebraska-Lincoln beef specialist said.

Last week's 80-degree days with relatively low humidity were a welcome relief, but now it's even more important producers make sure their cattle have plenty of water, said Terry Mader, beef specialist at UNL's Haskell Agricultural Laboratory near Concord.

"Cattle do not handle heat stress as well as humans," Mader said. "Sunny days with temperatures above the mid-80s can be stressful, particularly if there is no wind and humidity is above 50% or high due to a recent rainfall."Water is probably the best avenue to dissipate heat, Mader said.

"The cattle don't have to be thirsty, but as cattle drink water and pass it through their body, it removes a lot of heat in the process," he said.Cattle normally take in about 5 to 6 gallons of water per day. However, when temperatures rise, that amount can double or even triple.

"It's important to have plenty of available water," he said. "When there is competition for water, it creates problems because the dominant animals will occupy waterer space and not allow other animals access."

In an emergency, cattle can be sprayed with water to cool them down. However, once producers do that, they need to continue spraying. Spraying cattle with water will allow the animal to rapidly dissipate heat through evaporative cooling processes but this may limit the animal's ability to adapt to the heat.

"That's why it should only be used as an emergency step," Mader said.Producers also should have an emergency plan in case water supplies are low or cut off, Mader added.

In addition, producers should avoid handling cattle when it's hot and never after 10 a.m. Cattle body temperatures can rise 0.5 to 3.5 degrees during handling.

Also, producers should feed cattle most of the day's feed several hours after the day's peak temperature in the late afternoon or evening. Avoid filling cattle up with feed late in the morning when added heat generated by digestion will peak around the hottest time of the day, he said.

Cattle yards also should be inspected so there aren't any structures that restrict airflow. Cutting down vegetation around pens and moving cattle away from windbreaks can all help. Building earth mounds in pens also can increase airflow by preventing cattle from bunching together.

For more information about managing heat stress in feedlots, consult UNL Extension NebGuide G1409, Managing Feedlot Heat Stress.

Sandi Alswager Karstens
IANR News Service