Skip to main content
ARS Home » Research » Publications at this Location » Publication #79135
Title: HEAT WAVES IN RELATION TO THERMOREGULATION, FEEDING BEHAVIOR AND MORTALITY OF FEEDLOT CATTLE

Author
item Hahn, George
item MADER, T - UNIV NEBRASKA

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 2/28/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Heat waves can have severe consequences for all living beings, ranging from discomfort to death. A July 1995 heat wave in the mid-central United States caused extensive feedlot cattle death and performance losses, with an estimated $28 million economic consequence. This report analyzes that heat wave from meteorological and biological perspectives to illustrate the benefits of improved management when a heat wave is forecast. Specifically, the analysis shows the Temperature-Humidity Index (THI) to be a useful measure for profiling the potential impact of a heat wave, and provides suggested thresholds for initiating proactive management actions. The results emphasize the importance of recovery periods, as well as intensity and duration above heat stress thresholds, in potential feedlot cattle losses during hot weather.

Technical Abstract: Dynamic responses of growing, ad-lib-fed cattle to the onset of a heat wave are used to develop environmental management guides for limiting animal morbidity and mortality during the progression of a heat wave. A July 1995 heat wave in the mid-central United States, which caused extensive feedlot cattle death and performance losses, is used to illustrate how knowledge of the dynamic responses (especially body temperature and feed intake) in relation to increasing temperature and humidity (represented by the Temperature-Humidity Index [THI]) can benefit feedlot managers when a heat wave is forecast. An environmental profile developed from the analysis supports the use of THI greater than or equal to 79 as a threshold for feedlot cattle placed at risk, and suggests that several hours with THI greater than or equal to 84 and limited or no nighttime recovery periods with THI less than or equal to 74 can result in death of vulnerable animals unless immediate action is taken to limit excessive heat loads. These results emphasize the importance of recovery periods, as well as heat intensity and duration above stress thresholds, in thermoregulation and the potential for death losses in feedlot cattle during hot weather. Proactive environmental management counter-measures are suggested.