Heat storage, not sensible heat loss, increases in high temperature, high humidity conditions

Abstract

Because evaporative cooling is the principal avenue of heat loss at high ambient temperatures, high humidity superimposed on high temperature presents poultry with an additional thermal challenge. Whenever body temperature exceeds ambient temperature, sensible heat loss (radiation, conduction, and convection) to the environment will occur. The generally accepted model of heat balance, which states that when ambient temperature increases homeotherms will endeavour to maximize sensible heat loss before resorting to evaporative heat loss, was recently challenged. However, several factors that can influence heat balance were not considered in the reasoning pursued in that challenge. In this paper the theory behind heat balance models is discussed and the data that were used to challenge the model are reanalysed. The question of whether poultry are capable of physiologically increasing sensible heat loss under hot, humid conditions remains unanswered and presents an area worthy of future study.

Keywords:

• dry conductance
• evaporative heat loss
• humidity
• poultry
• sensible heat loss
• temperature