BEN SOUTH SAYS: Heat stress is a known ailment in poultry, both in commercial and backyard settings. Birds don’t sweat. They control their body temperature via evaporation through respiration and nonevaporation techniques in the form of radiation. Behaviours seen during heat-stress periods include birds lowering their body to the floor with wings outstretched to increase body-surface area, open-beak panting and searching for shade. Birds can deal with temperatures up to 28°C without too much problem, but excessive temperatures for extended periods can be detrimental to the bird’s health and egg production.

The possible consequences of excessive heat stress in chickens are: Eggshell changes due to a reduction in ionised calcium availability in the blood. This is because increased respiration leads to an increase in blood pH. Birds are more vulnerable to respiratory infection as they bypass natural filters within the nasal passages when openbeak breathing.
Food intake will drop, leading to reduced growth rate in young birds and disturbances in the gastrointestinal tract of older birds, which may cause diarrhoea.

Water intake will increase if access is good. The resulting electrolyte imbalances may result in the birds becoming severely dehydrated and listless.

Egg production frequently stalls or stops. Death will often occur if high temperatures remain as the bird’s body proteins begin to alter when core body temperature is more than 41°C.

It is vital that your birds don’t experience heat stress. Ensure that there are shaded areas for your birds. Chicken coops should have good air circulation throughout. The addition of a fan in larger houses can make a huge impact to air quality and circulation.

In excessive temperatures, consider using water sprinklers around the coop to help cool it. Ensuring that birds aren’t overstocked and that there is good access to cold, clean drinking water at all times is vital. If hot weather is forecast, I’d suggest adding some electrolytes to the water to replenish those potentially lost by the birds.