About ABE

Prospective Students

Undergraduate Students

Graduate Students

Industrial Technology
  Program

Faculty and Staff

Extension and Outreach

Research

Events and News

MWPS

Locator Map

Search

Due to the fact that the National Weather Service (NWS) has cut back on information that they provide to radio stations on livestock heat stress, the following heat stress index charts have been developed to aid producers in making management decisions in livestock and poultry production. The heat stress indices (HIS) combine the effects of both temperature and relative humidity, and classified as alert, danger, and emergency zones. Because different animal species and humans have different sensitivities to temperature and relative humidity, the heat stress charts are thus unique of that particular species. For example, compared to swine, cattle can tolerate much higher temperature at lower relative humidity. This difference arises from the fact that cattle exposed to hot temperature can dissipate their body heat more effectively by sweating, whereas swine or poultry do not have sweat glands. As temperature increases, thereby temperature difference between the environment and the animal narrows, more body heat has to be dissipated via the so-called evaporative heat loss mode. The natural capability of sweating by cattle gives them an edge over swine and poultry to rid of their body heat in the hot and dry conditions. By the same token, increase in relative humidity during hot weather will put cattle under stress much faster than for pigs or chickens. Table 1 lists the recommended management measures for each of the three HSI categories.

Table 1. Livestock/poultry heat stress index category and recommended management actions.