Heat Wave Forecasts Could Help Save Cattle By Ben Hardin
May 30, 1997
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
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,
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