Preparing for Heat Stress in Cattle Back »

Summer heat waves pose a serious danger to cattle. It’s not only the death loss, but also the loss in performance and the potential for poorer reproductive performance of bulls and breeding females caused by heat stress that cause economic harm to beef producers. Taking some steps now to plan ahead will put producers in a better position to deal with heat waves when and if they occur.

The amount of stress that cattle are under is affected by both the air temperature and the relative humidity. The following chart shows that relationship. The combination of high temperatures plus high relative humidity is particularly dangerous, especially when there is little to no night-time cooling. Producers can use this information plus livestock heat advisory alerts to make preparation for forecasted heat waves. Planning ahead is critically important as it’s too late to prevent problems after cattle are already under heat stress.

Chart from: Iowa State University, Department of Agricultural and Biosystems Engineering. Click the image to view a larger version.

While heat related losses can affect any class of cattle, in general cattle in confinement are at greater risk. There is typically greater air movement in a pasture, and in some cases greater opportunities for cattle to seek shade or ponds to cool off. Also, cattle fed on concrete or on a dark soil surface will have a greater exposure to radiant heat compared to cattle on grass. 

Water access is vitally important to maintain the well-being of cattle during hot weather. Water consumption may be 20 gallons per head at 90⁰ F, twice as high compared to 70⁰ F and 50% greater than at 80⁰ F. The capacity of your water system is also important. Some experts recommend having enough reserve capacity to provide half the animals’ daily needs in one hour, or to have 3 linear inches of trough access per head. In some cases producers might need to bring in extra tanks.

Heat stress can also be reduced by using sprinklers. It’s important to make sure the droplet size is large enough so that there isn’t a mist created that might only add to the heat stress by adding humidity. Cooling the ground can also provide relief. It’s important that a sprinkling program begin before the cattle are under stress. This is to make the cattle grow accustomed to sprinklers and fire hoses and avoid additional stress levels. An additional supply of emergency water may need to be acquired.

Providing shade and allowing for maximum air movement will also help provide relief. Shade will reduce the amount of radiant heat load the cattle would face, that is especially true with dark hided cattle. Removing barriers to air movement and/or giving cattle access to high mounds will also provide some relief.

Some other management steps to reduce heat stress related losses include:

  • Avoiding working cattle is also extremely important to minimize losses. If it is absolutely necessary to move or work cattle during hot weather, plan on being done before 9 to 10 a.m.
  • Controlling flies will help keep cattle from bunching in a group. That will allow more air flow to each animal.
  • Providing a layer of light colored bedding will reduce the temperature of the soil surface in an outdoor, unshaded pen.
  • Feed 70% or more of the daily ration in the late afternoon or evening. By delaying feeding, peak rumen heat production will occur during the cooler part of the day.
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