Poultry House Ventilation and Mortality Spike

The pattern points to heat stress compounded by poor airflow, not to a primary disease or a feed deficiency. Panting, wing-spreading and crowding near drinkers are classic heat dissipation behaviours, and they appear at midday when outside temperature is 34°C with high humidity. High humidity is critical because panting cools birds by evaporation; when humidity is high, panting becomes ineffective and mortality climbs quickly. The house configuration makes this worse: curtains half down on the windward side and a solid stack of feed bags on the leeward side block the cross-flow that an open-sided house depends on. The ridge alone cannot move enough air. Damp, caked litter adds humidity to the house air and reduces the birds' ability to lose heat. The farmer's response - electrolytes and denser feed - addresses hydration and nutrition but not the core problem. Electrolytes can help marginally, but denser feed increases heat production during digestion and can raise body temperature further. Adding feed also competes with the birds' reduced appetite. The real fix is airflow and heat load: open the house to cross-ventilation, remove the bag wall, and manage the litter. The weight gap (1.25 vs 1.4 kg) confirms the flock has already been under heat stress for some time.

Immediately (today): remove the stack of feed bags on the leeward side and roll both curtains fully down so air can move across the birds. This is the single highest-value action and costs nothing. Check that the ridge is clear and that no tarpaulin or stored equipment blocks it. Increase drinker space or add temporary drinkers, because crowding at drinkers during heat stress leads to birds being trampled and to unequal water intake. Provide cool, clean water and consider running water lines to keep it cooler. Within 24 hours: remove caked litter from the centre and replace it with dry litter; damp litter raises house humidity and ammonia. Reduce stocking density in the hottest part of the house if possible by spreading birds or opening more floor area. Shift feeding to the cooler parts of the day - early morning and late evening - rather than midday, so digestive heat does not coincide with peak temperature. Over 48 hours: review the feed - do not increase density further during a heat event; consider a diet reformulation with the nutritionist once the crisis passes. Record mortality, water intake and temperature twice daily so the effect of each change can be seen. If mortality does not fall within 24 hours of opening the house, call a veterinarian to rule out respiratory disease, since heat stress and disease can look similar.

The flock is 0.15 kg behind target at day 28, roughly 11% of target weight. The judgement depends on whether the gap is still growing or has stabilised. If the birds were on target until the heat event and the loss is recent, compensatory gain is possible once airflow is restored, because broilers can recover feed intake quickly. If the gap has been widening for two weeks, the flock has a chronic problem and market weight may be delayed or the birds sold lighter. To decide, weigh a fixed sample of birds - the same pen and roughly the same number - every three days and record average weight, feed intake, water intake, mortality and house temperature. Compare the growth rate before and after the intervention. If daily gain returns to the expected curve within a few days, keep the original market date; if not, recalculate the expected date and the feed cost to that date, and consider whether selling earlier at a lighter weight gives a better margin than feeding longer. Records should include date, sample size, average weight, feed delivered, water consumed, mortality and culls, and any treatments given. These records also protect the farmer if a buyer or insurer asks about flock performance.