Broilers start to suffer when the shed goes above about 30°C, and above 32°C the risk of deaths climbs fast, most of all for heavy birds in the last two weeks. The answer is a plan you follow every hot day: cool water always running, the most air you can move over the birds, no feed in the hottest hours for grown birds, and nobody disturbing the flock in the afternoon.
Why heat hits broilers so hard
A chicken has no sweat glands. It loses heat by panting, by holding its wings away from the body, and through air moving over its skin. A modern broiler also makes a lot of body heat because it grows so fast. So a 2 kg bird in a 40°C open shed in June is fighting heat from the sun, from the roof, from the litter and from its own body at the same time.
Humidity makes it worse. Panting works by drying moisture from the airways. When the air is already wet, as in the monsoon months, panting cools the bird less. A shed at 34°C with damp air can be more dangerous than 38°C with dry air.
Signs of heat stress, from early to dangerous
Walk the shed in the late morning and again at the hottest hour. Watch for:
- Early: birds panting with open beaks, wings held away from the body, less feed eaten, more water drunk.
- Middle: birds lying flat with legs stretched out, crowding along walls, under fans or near drinkers, droppings watery.
- Dangerous: birds not getting up, heads down, eyes half closed, very fast shallow breathing. Deaths often start in the heaviest birds.
The hot-day plan, hour by hour
On a hot day, follow the same plan every time. Write it on the wall for the workers.
| Time | What to do |
|---|---|
| Early morning (4 to 7 am) | Let birds eat in the cool. Check all fans, pads and the generator. Flush drinker lines. |
| Mid morning (8 to 10 am) | For grown birds, lift the feed or raise the feeders. Start pads or foggers as temperature climbs. |
| Hottest hours (11 am to 5 pm) | Water only. Keep air moving. Walk slowly through the shed every hour so birds stand and drink. Remove dead birds. |
| Evening (after 6 pm) | Put feed back once the shed cools. Keep fans on into the night if the roof is still hot. |
Workers should not catch, weigh, vaccinate or shift birds in the afternoon. Any of that work goes to early morning or night.
Water: the first line of defence
In normal weather a broiler drinks about twice as much water as feed by weight. In heat it can drink much more. If water runs short for even an hour in June, you will see it in deaths.
- Keep water cool. Water sitting in a tank on the roof can go above 35°C. Shade the tank, bury or cover pipes, and flush lines in the hottest hours so fresh water reaches the birds.
- Check every nipple line and drinker. Add extra drinkers in summer so weak birds do not have to walk far.
- Electrolytes and vitamin C in water are widely used in hot weather. Ask your vet or nutritionist which product and amount suits your flock, and do not mix several products at once.
Air speed, fans and cooling pads
Moving air over the birds removes heat, even when the air itself is warm. This is called wind chill, and for grown birds it is the strongest tool you have.
- Open shed: open the curtains fully on the shady side, use fans to push air along the length of the shed, and make sure nothing blocks the air at bird height. Whitewash or insulate the roof before summer; a hot roof radiates heat straight onto the birds.
- Control shed (tunnel): run all fans and pads at peak heat. Keep pads clean and wet evenly, with no dry strips. Check that air enters only through the pads, not through cracks.
- Foggers: good in dry heat. Stop or reduce them when the litter gets wet or the air feels muggy.
Cooling pads and foggers add moisture to the air. In dry May and June heat they can drop the shed several degrees. In humid July and August they cool far less, so do not rely on them alone; air speed over the birds matters more.
Read control shed vs open shed ventilation for minimum ventilation and fan setup.
Feed timing on hot days
Digesting feed makes body heat. For birds past about three weeks, many farms lift feed for roughly 6 to 8 hours over the hottest part of the day, then feed in the evening, at night and early morning. Water stays on the whole time.
This does not mean less feed for the batch. Birds eat more in the cool hours when feed is offered then. Do not withdraw feed from young chicks. If you are unsure about timing for your flock, ask your vet or feed nutritionist.
Before summer: fixes that pay back
Most heat deaths are decided before the heat wave arrives.
- Lower the number of birds. Fewer birds per square foot in summer means less body heat in the shed. See broiler stocking density by season.
- Prepare for load-shedding. A fan stopping at 2 pm in June can kill heavy birds within an hour. Test the generator, keep diesel, and know who switches it on. Read the load-shedding and generator plan.
- Roof and walls. Whitewash, thatch or insulation on the roof, shade nets on the sunny side, and trees or shade near the shed help.
- Plan the selling date. Heavy birds in a June heat wave are at the highest risk. Selling a few days early can be the better choice; run the numbers in the profit calculator.
After a heat wave
Once the shed cools, check the flock. Count and remove dead birds, look for birds with wet or caked litter under them, and watch feed intake over the next two days. Heat-stressed birds can be weaker against disease, so call your vet if you see breathing problems, unusual droppings or deaths that do not settle. A batch that went through a heat wave often shows a worse FCR, so note the dates of the heat wave next to your batch numbers.
Recording the shed temperature, water use and deaths every day in Poultry Curve lets you compare summers and spot the day things went wrong. If you are unsure what to do on a bad day, ask Helper, the assistant in the app, and always bring your vet in when birds keep dying.