'Keep cattle cool when humidity, temps rise'

LINCOLN—No wind along with high humidity and temperatures can spell disaster for cattle if proper procedures aren’t taken to ward off heat stress, a University of Nebraska-Lincoln beef specialist said.

During summer’s hot, humid days, producers need to make sure cattle have plenty of water, said Terry Mader, beef specialist at UNL’s Haskell Agricultural Laboratory near Concord.

“Water is probably the best avenue to dissipate heat,” Mader said. “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.”

Mader said normally cattle intake 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 said. “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, he said. Wetting these surfaces cools them down. These 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, Mader said.

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 said.

Also, be sure there aren’t any structures that restrict airflow.

It’s important to remember that cattle will adapt to weather conditions if they are given enough time, he said.

Usually it’s the rapid changes in weather that cause the biggest problems, Mader said.

“For most animals, give them three to four weeks to adapt to extremes, reduce feed intake, which will therefore reduce the metabolic heat load. Cattle won’t perform as well, but at least they’ll still be alive,” he said.

The first sign of heat stress in cattle is them standing up. This 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, Mader said.

Avoid handling cattle when it’s hot, Mader said. If it is necessary to process cattle, the earlier in the morning the better. Cattle’s body temperatures can rise 0.5 to 3.5 degrees during handling. Cattle that arrive at a packing plant with elevated temperatures can result in carcass defects.

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 said.

“We see the greatest stress problems when cattle consume large amounts of feed in the morning, then body temperatures shoot up in the afternoon and environmental temperatures rise rapidly,” Mader said.

Also, remember dark-hided cattle are more susceptible to heat stress than light-hided cattle, he said.

“So, watch for the first signs of heat stress in dark-hided cattle that are within 30 to 60 days of slaughter,” he said.

Lowering the energy content in feed also may reduce the amount of heat cattle generate during digestion and may help the animal cope with heat stress.