Feedlot Heat Stress Checklist

Abstract

The thermo-comfort zone varies greatly for beef cattle. Young animals have a narrow comfort zone between 45 and 80°F (7.2 and 26.6°C). The comfort zone of feedlot cattle and mature cows will range from subzero temperatures in the winter to around 75°F (23.8°C) in the summer, depending on body condition, hair coat length and plane of nutrition. This wide comfort zone allows cattle to thrive under diverse climatic conditions with little or no need for shelter or protection. However, unlike humans, who can be reasonably comfortable when exposed to normal summer temperatures, feedlot cattle have difficulty coping with temperatures above 90°F (31.9°C). This is particularly true when humidity is high or wind speed is low, especially when cattle have had little or no chance to adapt to excessive heat loads.