Introduction

Beef cattle producers are all too familiar with the brutal heat and humidity of summer in the southeast. Humidity severely compounds effects seen during high temperatures, further increasing the stress level on livestock, even on more temperate days.

As depicted in the Livestock Weather Hazard Guide shown here, cattle may begin suffering from heat stress while temperatures remain in the 70s. A general rule of thumb is that extreme stress starts at around 84 F and 84% humidity.1 It is important to note that not all animals handle stress equally. Brahman and Brahman-cross cattle are better adapted for dissipating heat than their English and Continental bred contemporaries. Furthermore, moderately conditioned cattle tolerate heat better than over-conditioned, and similarly lighthided cattle over dark hides.

A cow’s comfort zone is between 41 F and 77 F. When temperatures dip below 41 F, cattle reprioritize caloric usage. In response to the temperature dropping below the animal’s lower critical temperature, they begin burning calories to keep warm. Conversely, when an animal suffers from heat stress, calories are burned from increased panting and grazing is severely limited. Cattle limit grazing when their internal body temperature is elevated because the process of digestion produces extra heat. Aside from lowered average daily gain, producers can also expect to see a reduction in reproductive performance when temperatures are elevated.2

Summary

Beef cattle require between 15 and 40 square feet of shade per head depending on their age and production stage. Inadequate amounts of shade may lead to heat stress and a reduction in cattle performance. Extreme heat and lack of shade may result in death loss. Both natural and artificial shade sources carry advantages and disadvantages. It is important for the rancher to evaluate their operation and utilize different shade strategies that will provide the most effective solution for their ranch. Your local extension agent can assist with shade options and requirements for your operation.