Cows & Heat

Conduction – the transfer of heat through physical contact 

Heat moves to and from cow’s body through hooves, when lying down, when standing in water

Heat is transferred from the cow to cold drinking water. 

Convection – the movement of heat from the cow’s body to the air.

If there is a significant difference between the temperature of the air and the cow’s surface, convection will produce considerable cooling.

Air speed will increase the effects of convective cooling, so animals will try to stand where there is a breeze or under fans if they are provided.

Radiation – emission of heat to and from the cow and surroundings, directly from the sun or from re-radiation from hot ground, fences, buildings etc.

The difference in temperature between the cow and the surroundings will determine how much heat is gained or lost, as will the angle the cow can position itself to the sun.

Shading the cow from direct sunlight reduces the amount of solar radiation it receives by 50% or more.

Black coated cows absorb more solar radiation than cows with lighter coloured coats. However, black coated cows will re-radiate heat more effectively at night.

Cows with dense, flat coats (such as Brahmans) resist heat transfer to the skin more than woolly coats (European breeds).