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Plan ahead to avoid heat stress in cattle

AgDM Newsletter
July 2011

With the weather forecast of temperatures in the mid-to upper 90s and heat index expected to top 100 degrees in Iowa this week, Iowa State University (ISU) Extension beef veterinarian Grant Dewell reminds beef cattle producers that preparing for these weather conditions is vital to maintaining herd health.

Five steps to avoiding heat stress in your herd are:

1. Plan ahead. After cattle get hot, it’s too late to prevent problems.

2. Don’t work cattle when it is hot. Finish working cattle before 9 to 10 a.m. in summer, and remember that during a heat wave it’s best to not work cattle at all.

3. Provide plenty of fresh, clean water. When it’s hot and humid, consuming water is the only way cattle can cool down. Make sure the water flow is sufficient to keep tanks full, and ensure there’s enough space at water tanks (3 inches linear space per head). Introduce new water tanks before a heat event occurs so cattle know where they are.

4. Feed 70 percent of the ration in the afternoon. Heat from fermentation in the rumen is primary source of heat for cattle. When cattle are fed in the morning, peak rumen temperature production occurs during the heat of day when they can’t get rid of it. By feeding 70 percent of the ration in late afternoon, rumen heat production occurs when it is cooler.

5. Provide ventilation, shade and/or sprinklers. Environmental temperatures compound the heat load for cattle during a heat wave. Remove objects that are obstructing natural air movement. Indoor cattle will benefit from shade provided by the building as long as ventilation is good. Outdoor cattle will benefit from sprinklers to cool them off. Make sure cattle are used to sprinklers before employing them during a heat wave.

Factsheets on dealing with heat stress, resources and ISU Extension staff who can help are available on the Iowa Beef Center (IBC) website. Dewell offers more details on heat stress in a longer article on the ISU Veterinary Medicine Beef Extension website. Keep an eye on the 7-day heat stress forecast for your area at the USDA’s Agricultural Research Service website.


Grant Dewell,extension beef veterinarian
Sherry Hoyer, Iowa Beef Center communications