Actions to Minimize Heat Stress
Prepare - Plan - Be Proactive
Actions to be taken before an extreme heat event:
1. Monitor the weather.
2. Prepare a summer feeding program, which is a low heat increment diet, to feed the cattle during heat waves.
3. Ensure that there are no restrictions to air movement such as hay storage locations or wind breaks.
4. Check stock tanks to ensure adequate water.
Make sure to have adequate access for multiple animals to drink at one time. Check reserves, pumps, and all parts of the watering system.
Check the refill rate of the stock tanks; remember in the summer when many animals are drinking many tanks will be trying to fill at one time in addition to other potential needs for water on the same water supply line. During the summer water intake may exceed 9 gallons per head per day.
Midwest Plan Service suggests a water space requirement of 1.5 inches per head. For example, 100 head of cattle would need 150 inches of water tank perimeter.
5. Water intake decreases when water temperature exceeds 80°F. As a result, ensure that water pipes are not exposed to sun. Pipes should be at least 2 feet underground.
6. Consider the use of additional water tanks.
7. Consider added shade at least over the sick pens, and possibly over other vulnerable animals.
8. Remove manure build up from around water tanks, feed bunks and under shade. Manure build up should not exceed 1 inch in depth.
Actions to take during an extreme heat event:
1. DO NOT MOVE ANIMALS.
2. Observe animals for signs of heat stress.
3. Consider wetting the animals or the ground.
When wetting the animals use large droplets (150 micron diameter sprinklers) not a fine mist. Wet the animals to the hide. This means saturating the hair for maximum cooling effect. The water should run off the animals. Wetting is efficient where there is wind and low relative humidity. Night sprinkling may be effective. Ensure that there is adequate water to maintain cooling. Once sprinkling commences it will need to continue until the heat wave conditions abate. Be prepared to sprinkle for up to 5 days. If pens are wet, after rain for example, adding water will further increase humidity within the pen. Consider multiple sprinklers, a minimum of 3 per pen, at various locations within a pen. These sprinklers can be turned on and off in attempt to reduce mud holes. Avoid locating sprinklers around water tanks, feed bunks, or shade.
Use caution if fire trucks are used to wet cattle. If cattle are not used to this treatment they may run away from the water, which could make the situation worse.
The soil in a feedlot absorbs and retains heat well. Ground temperatures in the feedlot are typically 20 50 °F warmer than the air temperatures. During an extreme heat event the surface of the feedlot can exceed 150 °F. Adding water to the ground will cool the surface as the water evaporates. Be careful not to create mud holes.
Many of these recommendations are based on the practical experience of Dr. John B. Gaughan of the University of Queensland, Gatton, Australia. Dr. Gaughan is an expert in the area of cattle heat stress.