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Title: A CLIMATOLOGICAL PERSPECTIVE ON FEEDLOT CATTLE PERFORMANCE AND MORTALITY RELATED TO THE THI

Author
item HUBBARD, K - UNIV NEBRASKA
item STOOKSBURY, D - UNIV OF NEBRASKA
item Hahn, George

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 8/4/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Temperature-Humidity Index (THI) has been used for many years as an environmental management tool for livestock operations during hot weather. Three livestock safety categories (Alert, Danger, Emergency) are used. The Emergency category is recognized as representing conditions that cause severe performance penalties and possible death in feedlot cattle. This report provides technical information to livestock managers about the likelihood of reaching the Emergency category of THI. A heat wave in July 1995 caused an estimated $28 million loss to feedlot owners as it progressed through KS, NE, MO and IA. A heat wave of equal magnitude is estimated to occur once in 20 yrs, on average. Such climatic analyses provide a basis for evaluating risks associated with hot weather and for improving the selection of feedlot environmental management strategies to minimize the effects of hot weather extremes.

Technical Abstract: The Temperature-Humidity Index (THI) has been used for many years as an environmental management tool for livestock operations during hot weather. Three livestock safety categories (Alert, Danger, Emergency) are used, with the Emergency (THI equal to or greater than 84) category recognized as representing conditions that cause severe performance penalties and sometimes death in feedlot cattle. This report quantifiess, for the High Plains region of the United States, probabilities of single-day and heat wave events (defined as THI equal to or greater than 84) to obtain a) the total number of events, b) the duration of events, c) the magnitude (THI-hrs) of events, and d) the degree of recovery (THI equal to or less than 74) during events. Areal distribution maps of the probabilities of THI equal to or greater than 84 are presented and discussed in the context of a 4-5 day July 1995 heat wave event. This heat wave was associated with more than 4000 feedlot cattle deaths as it progressed through KS, NE, MO and IA, with an economic impact estimated at $28 million. The analyses indicated the recurrence interval for a 4 to 5 day heat wave is, on average, once in 10 yrs, and that the severity in magnitude, duration and recovery similar to the 1995 event recurs once in 20 yrs, on average. Such climatic risk analyses provide a basis for more informed selection of feedlot environmental management strategies to minimize the effects of hot weather extremes.