At 1.6kg+, broilers generate immense metabolic heat (~7–8 Watts per bird). During hot ambient periods, natural convection and radiation are inadequate to dissipate this thermal load. High-velocity air movement across bird skin combined with staged evaporative cooling pad operation is critical to prevent fatal heat stress.
•Running evaporative pad pumps continuously in humid weather (RH >80%), turning the poultry house into a suffocating sauna.
•Activating cooling pads before all tunnel exhaust fans are running at 100% capacity.
•Allowing cooling pad sumps to run dry or become clogged with algae and mineral scale, causing uneven air intake.
•Letting drinking water sit stagnant in hot pipes, depriving heat-stressed birds of their primary internal heat-dump mechanism.
•Panting causes rapid loss of CO2, leading to respiratory alkalosis and electrolyte depletion (potassium and bicarbonate). During severe heat episodes, supplement electrolytes (potassium chloride and sodium bicarbonate) and Vitamin C in drinking water.
•Clinical escalation trigger: If heat-related mortality exceeds 0.10% in a single afternoon or if dead birds show severe lung congestion and subcutaneous blood pooling, contact the poultry veterinarian immediately.
•Never run cooling pad pumps if the shed relative humidity is already above 75%. Air velocity is what cools birds at high humidity; adding water when air is saturated only suffocates the flock.
•Walk the house very slowly during hot afternoons. Gently moving birds makes them stand up and exposes their bare underbellies to the tunnel wind-chill.
When air moves over fully feathered broilers at 2.0–2.5 m/s, it rapidly strips the boundary layer of trapped warm air from between their feathers. This convective heat transfer lowers the bird's perceived (effective) temperature by 4–6°C below the actual thermometer reading.
Only turn on pad pumps after all tunnel exhaust fans are already operating at 100% and house temperature exceeds 28°C (82°F), provided shed relative humidity is below 75%. Use timer pulsing rather than continuous pumping to avoid over-humidifying the house.
Broilers cannot sweat; drinking cool water (<20°C) acts as an internal heat sink, absorbing core body heat and carrying it out through excretion. Warm water (>26°C) worsens thermal distress and accelerates collapse.
