Watch for Heat Stress in Cattle

Tools, Tactics Available to Help Keep Animals Cooler

Russ Quinn
By  Russ Quinn , DTN Staff Reporter
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Cattle in feedlots are susceptible to heat stress from high temperatures and humidity, but there are certain management practices that can help to lessen the effects. (DTN Photo by Jim Patrico)

OMAHA (DTN) -- After a cool spring, high temperatures and humidity arrived in much of the center of the country once the calendar flipped to June. The seemingly endless cloudy days gave way to warmer than average conditions.

Cattle producers should establish certain protocols to protect livestock from heat stress. In addition, there are several tools available to monitor weather conditions to know if additional actions are needed.

HEAT AFFECTS CATTLE

In a Kansas State University (KSU) Beef Extension webinar titled "Managerial Tools and Tips in an Uncertain Climate and Market" from June 4, speakers discussed various beef cattle-related topics, among them the higher temperatures and proper heat stress management.

Kansas State Climatologist Mary Knapp said the current weather situation in the state is too much rain in southeastern Kansas and not enough in the western areas of the state. Different designations of drought ranging from moderate to extreme are currently found in the western half of Kansas.

"We think the report next week will show (drought) expansion in more southern areas of the state," Knapp said.

Knapp said the June outlooks are calling for below-normal precipitation and above-normal temperatures. However, the summer outlook (June, July, August) still calls for above-normal precipitation probability, she said.

High temperatures and rising levels of relative humidity is a bad combination for both feedlot and cow/calf operations, according to A.J. Tarpoff, KSU Extension veterinarian. Cattle in feedlots can have higher levels of mortality while cows in cow/calf operations tend to have issues with low levels of reproductivity if heat stress is bad enough.

Tarpoff said cattle dissipate heat less efficiently than other animals. They will pant in an attempt to remove the heat through respiratory methods and will also sweat some, but they only sweat about 10% as much as human beings.

Several factors affect how cattle dissipate heat, including body condition score (bcs), weight, existing health issues, hair color and hair coat thickness.

"Some cattle still have their winter coats, which makes handling heat stress more difficult," Tarpoff said.

The internal temperature of cattle peaks two hours after the peak of the environmental temperature, so even though the hottest part of the day is over, cattle could still be extremely hot. It takes at least six hours to dissipate the heat load on cattle, he said.

Tarpoff said day after day of hot conditions creates an accumulated heat load on cattle. This load is not able to be dissipated with just one overnight period, he said.

MANAGEMENT CONSIDERATIONS

There are certain management practices that may limit the effects of heat stress on cattle.

Tarpoff said cattle producers should have a plan in place to handle these conditions before the heat arrives. He encouraged webinar participants to develop a protocol for these conditions and educate all people who will be working with the cattle.

The feeding of cattle should be altered some in hot conditions. Tarpoff recommends reducing feeding activity during the hottest part of the day, specifically 70% of the daily feed offer could be delivered as late as possible in the afternoon.

Another management consideration would be handling cattle. Never process cattle in the heat of the day, and if you do have to work cattle, try to finish this chore by 10 a.m., he said.

HEAVIER CATTLE PRESENT STILL

Warren Rusche, South Dakota State University Extension beef feedlot management associate, recently wrote about heavier cattle in feedlots due to the COVID-19 pandemic are more susceptible to heat stress. (https://extension.sdstate.edu/…)

Because of the disruptions in the beef processing sector in recent weeks, there could be issues with the orderly marketing of finished cattle. Harvest-ready cattle may still be in the feedyard and heavy cattle could be there for the foreseeable future, he wrote.

Fatigued Cattle Syndrome (FCS) is a condition which affects cattle mobility near the time of processing, he said. Cattle affected by FCS display an unwillingness to move or in severe cases can go down.

Rusche said feedlot personal should move these cattle more slowly, and cattle walked to a load-out area were much less likely to develop FCS compared to those who were handled at a trot. If possible, move these cattle to a pen closer to the load-out area, which will minimize the distance the cattle need to travel on shipping day.

Rusche said feedlot operators will need to be aware of increased animal health concerns as higher temperatures arrive. Heavier cattle don't tolerate higher temperatures as well, especially if they are black-hided animals.

"Strategies, such as shades or sprinklers, can make a big difference in relieving heat stress conditions in feedlot cattle," Rusche wrote.

Tarpoff said sun shades and sprinklers can be useful if they are used correctly.

Sun shades should cover 20 square feet per head per pen. This is a considerable investment, so maybe an economic method of incorporating shade use would be using it on the heaviest cattle or sick pens, he said.

Sprinklers should be used to wet cattle but not create mud in the pen, Tarpoff said. They should be used in early morning hours or overnight and shouldn't be run in the heat of the day as it increases humidity in the pen environment.

Water availability should be watched closely during rising temperatures. Feedlot cattle should have 2 to 3 inches of trough space per head, he said.

"As the temperature goes from 70 degrees to 90 degrees, that animal will consume double the water consumption," he said.

HEAT STRESS TOOLS AVAILABLE

Tarpoff said cattle producers have many tools to monitor conditions available to them.

One of the most basic tools would be the temperature and humidity index chart, which can found in many different places. By knowing the temperature and humidity, producers can get a snapshot in time of current conditions and make pinpoint decisions from there, he said.

Another useful tool would be the U.S. Meat Animal Research Center (USMARC) Forecast Maps. This website consists of a seven-day forecast of cattle heat stress for the continental U.S., Tarpoff said.

You can click this link to see the map: https://www.ars.usda.gov/…

For Kansas cattle producers, the Kansas Mesonet Animal Comfort Index (https://mesonet.k-state.edu/…) can give an up-to-the-minute update of heat stress across the state. A chart can be constructed to give even more details of heat stress in the last seven days, he said.

The University of Nebraska-Lincoln (UNL) Extension also recently wrote an article detailing practices cattle producers should consider to combat heat stress.

The article can be found at: https://beef.unl.edu/…

Russ Quinn can be reached at russ.quinn@dtn.com

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Russ Quinn