High Heat And Humidity Cautions For Livestock

High Heat And Humidity Cautions For Livestock

Hot weather is here; Iowa State University Extension veterinarian advises you take steps to protect cattle from danger of heat stress.

By Christina Dittmer

The USDA/NOAA forecast for heat stress in cattle is at the danger level for Monday, July 21 and at the extreme level for Tuesday, July 22. The Iowa Beef Center has posted this caution on their website, along with other resources, including information from Grant Dewell, Iowa State University Extension beef veterinarian.

HEAT STRESS DANGER: The USDA/NOAA forecast for heat stress in cattle is at the danger level for Monday, July 21 and at the extreme level for Tuesday, July 22.

Dewell wrote an article titled "Heat Stress in Cattle" offering helpful tips to use to protect the animals on hot summer days. Dewell says cattle are particularly susceptible to heat stress because they can't dissipate their heat load effectively, compared to other animals. Cattle that may be at extra risk include animals that are in feedlots, are heavier, black in color and respiratory compromised, he says.

Manage water availability, feeding and shade
In managing heat stress in cattle, Dewell recommends increasing water availability, establishing alternate feeding routines, ensuring the availability of shaded areas and air movement, controlling flies and using sprinklers. Providing plenty of available drinking water is the quickest way to cool your cattle's body temperature, and along with additional perspiration, water intake will increase. Dewell recommends having additional water tanks available, getting them ready prior to extreme heat events, and keeping the water clean to encourage the animals to drink.

"Heat production from feed intake peaks four to six hours after feeding," he says. Therefore feeding in the morning can cause body temperatures to peak during the hotter part of the day. Dewell says feeding at least 70% of the daily feed two to four hours after peak ambient temperature and reducing diet energy content by 5% to 7% can help decrease the animal's heat load.

Especially with black cattle, shade can be a vital aspect in surviving an extreme heat event, and 20 to 40 square feet of shade per animal is recommended, Dewell says. He notes that if the shade structure is oriented east-west, the shade will be cooler, and a height of at least 8 feet can help keep air flowing under the structure.


Removing tall weeds, creating mounds and identifying pens with poor air circulation as to not house market weight animals in them during peak temperatures can help the animals stay cooler by means of air circulation.

Providing sprinklers requires additional planning
When flies bite, cattle can bunch up, Dewell says, causing less efficient dispersion of heat. By working to remove fly breeding areas and applying insecticide to control flies, fly populations can be decreased, benefiting the cattle.

Sprinklers, while effective in cooling animals by using evaporation and cooling the ground, should be set to thoroughly wet the animals, and not just mist the air, he adds. The sprinklers should also be used prior to extreme heat so as to not cause thermal shock to the animals. And use the sprinklers in intervals to avoid mud, use them away from feed and away from where waterers are located. Continue to use the sprinklers for a while after extreme heat events are over, to ensure the animals can manage without them.

Monitor cattle in feedlots and use effective strategies
Dewell says any time the temperature-heat index, or THI, is above 80, cattle will experience heat stress. He highly encourages that you monitor the animals to ensure heat stress is not too severe. "Initially, feed intake will drop off and cattle become restless," he notes. "As heat stress increases, the cattle will begin to slobber and their respiration rates will increase. Eventually, cattle will begin to group together. In severe heat stress cattle will be open mouth breathing with a labored effort. Feedlots need to be monitored for heat stress and you need to implement strategies promptly to minimize impact on cattle to prevent severe death from heat stress."

For more information on the cautions and care to take to mitigate heat stress on cattle, click here. For Dewell's full article, click here. For resources during high heat, click here, and for more information from IBC visit the IBC website.

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