Air movement and the thermal microclimates observed in poultry lairages.

1. The thermal environment experienced by broilers during transport and a 4 h lairage period were recorded for 8 loads of birds to 2 processing plants under summer and winter conditions. 2. During the transport period the thermal environment was considered not to have been a significant challenge to bird welfare. 3. During the lairage period, over all 8 d, external ambient temperatures were in the range 4 degrees to 15 degrees C during the winter trials and 12 degrees to 29 degrees C during the summer. Temperatures amongst the crated birds for this period were in the range 16 degrees to 29 degrees C and 20 degrees to 31 degrees C during the winter and summer trials respectively. 4. Air velocity measurements at bird level indicated air movement was of small magnitude (typically < 0.1 m/s) and of variable direction, despite the large air movements around the modules with speeds of over 1 m/s. 5. The potentially stressful thermal environments observed during lairage were achieved rapidly (< 1 h) after unloading. It is considered, therefore, that the minimisation of holding time alone is not a suitable control strategy. 6. The use of water-misting sprays as a control strategy in one lairage was observed to lower the temperature throughout the lairage but raised the humidity, which might offset the temperature advantage to the birds' thermoregulatory ability. 7. More closely controlled environments for broiler lairage facilities are suggested, with further work to increase air movement at bird level.