Heat Wave Forecasts Could Help Save Cattle

MINNEAPOLIS, May 30--Strings of scorching days and muggy nights could push feedlot cattle perilously close to death unless feedlot managers keep a close eye on weather forecasts and take precautions to protect the animals, a U.S. Department of Agriculture scientist warns.

G. LeRoy Hahn, an agricultural engineer with USDA's Agricultural Research Service, said hot weather management options may include having water sprinklers available to provide relief, avoiding handling or transporting cattle, providing adequate shade, ensuring that livestock waterers are clean and working well, and providing at least two waterers per pen. Hahn conducts research at the Roman L. Hruska U.S. Meat Animal Research Center in Clay Center, Neb.

Speaking here at the Fifth International Livestock Environment Symposium sponsored by the American Society of Agricultural Engineers, Hahn reported on an ARS-led study of the impact on livestock from the July 1995 heat wave in the mid-central United States. That heat wave is estimated to have cost the U.S. cattle industry $28 million in animal deaths and reduced livestock performance. But it also gave researchers an opportunity to more closely study temperature and humidity conditions linked to livestock deaths.

In his studies on the effect of heat stress on cattle, Hahn used a Temperature-Humidity Index (THI) chart that can be viewed on the World Wide Web at:

http://www.ianr.unl.edu/pubs/Animals/g57.htm

The Clay Center studies indicated one or two days of exposure to THI's in the "emergency" category don't necessarily cause cattle deaths. However, heat waves that lasted three or more days with daytime exposure to THI's above 83, combined with THI's above 74 at night, deliver a one-two punch strongly associated with losses of vulnerable animals. "Hot conditions at night don't give the animals an opportunity to recover from the heat stress of the day," Hahn said.

The Clay Center researchers are now studying whether feedlot cattle's feed should be reduced a day or two ahead of a predicted heat wave. As cattle digest feed, they generate body heat, so reducing the feed intake could cut down on the animals' overall heat levels during especially hot weather, Hahn said.

Scientists, engineers, economists and other professionals gathered at the symposium to discuss research on creating and managing humane, sustainable, environmentally friendly, safe, economical and productive livestock environments. The symposium started May 29 and ends May 31.

Scientific contact: G. LeRoy Hahn, Roman L. Hruska U.S. Meat Animal Research Center, Agricultural Research Service, USDA, Clay Center, NE 68933, phone (402) 762-4271, fax 762-4273, e-mail [email protected].