AABP Executive Director Dr. Fred Gingrich is joined by Dr. Dan Thomson from the Department of Animal Science at Iowa State University to discuss the effects and mitigation strategies resulting from heat stress in feedlot cattle. We discuss that heavy and black-hided cattle are at increased risk of heat stress, and control strategies should first target these groups of cattle when the temperature-humidity index (THI) is greater than 70 degrees F. Thomson states that the first thing cattle will do when experiencing heat stress is stand up, pant and decrease intakes. Bedding placed in pens can reduce surface temperatures by 20-30 degrees F, and providing shade that moves with the sun will also help to cool cattle. Building mounds for cattle to be further away from surface heat and allow more exposure to moving air will also decrease heat stress in cattle. Thomson reminds our listeners that water is the most important nutrient to cattle, especially in times of heat stress events. Cattle will drink 3x dry matter intake normally, but during hot weather they will drink 5x dry matter intake. Ensuring access to clean water with adequate trough space is important. We also discuss removing barriers to airflow in feedlot pens and using low stress handling techniques or stopping all movements during times of intense heat stress. Thomson also discusses his television show Doc Talk which is available on RFD TV and has a wide audience for discussing issues important to cattle veterinarians and producers. Find show times or stream the show online at this link.  

Links

 Dynamic Response Indicators of Heat Stress in Shaded and Non-shaded Feedlot Cattle, Part 1: Analyses of Indicators
T.M. Brown-Brandl, R.A. Eigenberg, J.A. Nienaber, G.L. Hahn 

Influence of shade on panting score and behavioural responses of Bos taurus and Bos indicus feedlot cattle to heat load
A.M. Lees, J.C. Lees, V. Sejian, M.L. Sullican, J.B. Gaughan

Iowa State University Managing Heat Stress in Feedlot Cattle Resource