High temperatures and high humidity are not an ideal combination for cattle. According to Erin Laborie, Nebraska Extension educator, cattle do not handle heat stress as well as humans do.
The range of temperatures in which cattle do not use additional energy to maintain core body temperature is referred to as the thermoneutral zone. This zone generally ranges from 32°F to 75°F for cattle but can vary depending on metabolic size.
When temperatures exceed the upper critical temperature, cattle expend energy in an attempt to dissipate heat. Panting and elevated respiration and heart rate are signs this is occurring. When temperatures remain above 70°F during the night, cattle are unable to recover before the next episode of heat exposure.
Heat stress can result in reduced intake and gains and — in extreme cases — can lead to death.
AJ Tarpoff, DVM and Kansas State University extension veterinarian, says producers should look for drool as an early sign of heat stress. Then panting begins, which progresses to open mouth panting and a visible effort to breathe.
While cattle producers can’t control the heat, there are some things they can do to help cattle cope with high temperatures and humidity. Consider these tips from Michigan State University Extension to make sure your cattle stay comfortable:
Avoid handling, transporting, moving or processing cattle.
Reschedule anything that will add stress to cattle, like gathering, turning bulls out or preconditioning if it’s an option. If cattle must be handled, work them in the early morning hours using low-stress handling techniques. Problems often occur during stressful events.Cattle’s core temperature peaks two hours after the peak environmental temperature. It also takes at least six hours for cattle to dissipate their heat load. Therefore, if the peak temperature occurred at 4 p.m., cattle will not have recovered from that heat load until after midnight. It will be later than that before cattle have fully recovered from the entire day’s heat load.
Have a backup plan ready if power or water systems fail.
Offer additional water.
Make sure cattle have access to plenty of clean water, and that there is enough access space for all cattle — including calves — to get to water. The water requirements of cattle increase during heat stress. Cattle lose water from increased respiration and perspiration. Consumption of water is the quickest method for cattle to reduce their core body temperature. The rule of thumb is to have 3" of linear water space per head during the summer.Multiple cattle need to be able to drink at the same time. Waterers should be kept clean and cool.
Cattle prefer water between 40°F to 65°F. Water intake decreases when water temperature exceeds 80°F.
Ideally, water sources should not be exposed directly to the sun. Producers can help keep the water cooler by ensuring that the water lines are covered by grass in the fence rows.
Provide shade.
If you have the option, move cattle to a pasture that offers shade, or use portable windbreak panels to create shade.During heat stress days, shade is critical especially for dark-haired, fleshy, young and older cattle. Shade can easily be provided by allowing access to pasture with trees or access to open buildings. If shaded pasture acres are limited, avoid grazing them during the days with normal temps to allow forage to be there when heat stress temperatures arrive.
To be effective, there needs to be 20 sq. ft. to 40 sq. ft. of shade per animal. If using a mechanical shade structure, an east-west orientation will permit the ground under the shade to remain cooler. However, if mud is an issue, a north-south orientation will increase drying as the shade moves across the ground during the day. The height of the shade structure should be greater than 8' tall to allow sufficient air movement under the shade.
Supply adequate ventilation.
Increasing the air flow can help cattle cope with extreme heat events. Wind speed has been associated with the ability of cattle to regulate their heat load. Although producers cannot influence wind speed, they can ensure there are no restrictions to air movement such as hay storage, tall vegetation or wind breaks.If cattle are being fed and housed in an enclosed barn or building, use fans to move air through the building, open the sides of the barn or provide access to an outside pen or pasture with shade. Using sprinklers in this situation can potentially intensify the problem and create more humidity without proper air movement to remove it from the building.
- Consider surface area.
Access to surfaces that are covered with vegetation will help cattle keep their temperatures lower.
The Temperature Humidity Index chart and your state’s mesonet cattle comfort index can be helpful in determining when cattle are at risk for heat stress.
“Being proactive rather than reactive is important for avoiding any train wrecks when it comes to heat stress,” Laborie sumarizes.
Your Next Read: Beat the Heat: Essential Tips for Cooling Cattle Effectively
