Heat stress in an open-sided house: the hours that kill

Why heat kills

A chicken gets rid of its heat through the air it breathes (it pants) and through contact with air cooler than itself. Above 30 to 32 °C, especially with humidity, it can no longer manage: its temperature rises, it stops eating (digesting produces heat), it drinks enormously, then it collapses. The most at risk: heavy birds (white broilers over 3 to 4 weeks), dense flocks, houses that are poorly oriented or closed, and birds that have eaten just before the hot hours.

The signs

• Beak open, rapid panting, wings held away from the body, birds lying down, spread out on the litter.
• Rush to the drinkers, birds lying under the drinkers or against the walls.
• Feed consumption falling, water consumption doubling.
• Mortality in the afternoon, heavy birds found on their backs; in layers, thin shells and a drop in laying.

Act within the hour

• Water: replace with cool water from the reserve (never warm), add drinkers, check the flow at the end of the line.
• Air: open all the curtains, ridge open, circulating fans if you have them, positioned to move the air at bird height without blocking it.
• Roof: spray the metal roof (or wet it with a hose): a few degrees less immediately. A mister or a fine spray of the air where the wind comes in helps, provided the air is moving (otherwise you are adding humidity).
• Feed: remove it or do not distribute it between 11 am and 4 pm; feed early in the morning and in the evening, with the light on at night so they eat in the cool.
• Calm: no weighing, no vaccination, no handling during the hot hours.
• Electrolytes and vitamin C in the water as advised by the veterinarian or the supervisor.

Preparing for the hot season

• Reduced stocking density: 8 white broilers per m² instead of 10, or sell earlier (1.8 kg instead of 2.2).
• Roof: paint the metal sheets white (lime or paint): up to 5 °C less under the roof; insulate under the sheets if possible; overhang and shade.
• Surroundings: trees at a distance (shade without blocking the wind), ground around not concreted if possible.
• Water: reserve in the shade or whitewashed, pipes buried, two days' stock.
• Planning: orders planned so that heavy flocks do not fall in March-April, or choose coloured chickens, which are hardier, for this period.
• Harmattan: the opposite, cold nights and dust, curtains closed at night; but the afternoons stay hot and dry: water matters just as much.