Thermal interaction between animal and microclimate: Specification of a “standard environmental temperature” for animals outdoors

Abstract

An index is developed from heat transfer theory to describe the thermal environment experienced by animals outdoors. This index, termed the “standard environmental temperature”, is defined as the air temperature in an isothermal laboratory where the walls are at air temperature and there is no sunlight, and at which temperature the total rate of heat loss from the body surface is the same as in the actual environment. Standard values are assumed for the humidity and convection conditions in the laboratory. Values of standard environmental temperature are presented for cattle exposed to sunlight, wind and different humidities outdoors. These values can be more than 15°C above or below the actual air temperature, depending on the conditions.