Terry Mader, University of Nebraska beef specialist in Concord, says that during summer's hot, humid days, producers need to make sure cattle have plenty of water. "Water is probably the best avenue to dissipate heat," Mader says. "The cattle don't have to be thirsty, but if they can consume water and pass that out as urine it removes a lot of heat from the animal in the process."
Normally, cattle take in about 5 to 6 gallons per day, depending on the animal. However, that can double or even triple in some feedlots when temperatures rise.
"It's important that cattle have plenty of access to the water trough as well," he says. "When there is competition for water space, that creates problems because the dominant animals will occupy waterer space and not allow other animals access."
Wetting pen surfaces also is beneficial for cooling animals by providing a cool place for cattle to go. Dry surfaces in feedlots can reach temperatures of 150 degrees. Wetting these surfaces cools them down. The surfaces will remain cooler until the added water evaporates, which sometimes can take more than 24 hours.
In an emergency, cattle can be sprayed with water to cool them down. However, once producers start doing 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 animals' ability to adapt to the heat. That's why it should only be used as an emergency step.
Producers also should have an emergency plan in case water supplies are low or cut off.
"Have a plan for obtaining water that is safe for cattle to drink if an emergency should arise," he says.
Also, be sure there aren't any structures that restrict airflow.
The first sign of heat stress in cattle is them standing up, which allows them to expose more of their body surface to dissipate heat. Cattle also will bunch when they are hot, and flies and other stressors will only compound the problem.
Avoid handling cattle when it's hot. If it is necessary to process cattle, the earlier in the morning the better.
Mader also suggests feeding cattle most of the day's feed several hours after the day's peak temperature in the late afternoon or evening. Avoid filling up cattle with feed late in the morning when the added heat generated by digestion will peak around the hottest time of the day, he says.
Also, remember dark-hided cattle are more susceptible to heat stress than light-hided cattle, he says.
For more information about managing heat stress in feedlots, consult UNL Extension NebGuide G1409, Managing Feedlot Heat Stress, available on the Web at www.ianrpubs.unl.edu/sendIt/g1409.pdf.