VEHICLE DESIGN AND THERMAL COMFORT OF POULTRY IN TRANSIT

1. Four second-generation artificial chickens (Glorias) simulated the sensible heat exchanges, H, of pullets and end-of-lay hens which they accompanied throughout commercial transit in different sites of the lo ads. 2. Data from two summer and two winter journeys on each of 5 natu rally-and 2 fan-ventilated vehicles were used to derive general equati ons to predict H and temperature lift for each vehicle. 3. From these, air movement, V, within the crates was calculated together with predi cted H at ambient temperatures to compare the thermal comfort of the v ehicles. 4. All naturally-ventilated vehicles were over-ventilated in motion, with mean V ranging from 0.9 to 2.4 m/s within the crate, and maximum V of 6.0 m/s resulting in negligible temperature lift above am bient. Poorly-feathered hens were, consequently, extremely cold-stress ed in winter. When stationary, vehicles with a central passage that en abled the 'stack effect' to operate were thermally comfortable provide d V was kept low. Designs stocked over the whole floor area of the veh icle were too hot. 5. Fan-ventilated vehicles had a similar range of H whether stationary or in motion. The mean V of 1 to 2 m/s of bird-war med air maintained satisfactory thermal conditions most of the time. 6 . For current designs of poultry vehicle stocked at commercial rates, V should normally be between 0.3 and 1.0 m/s; air temperature near pul lets or broilers should be 10-15 degrees C and near poorly-feathered h ens 22-28 degrees C. Suitable ventilation rates are likely to be in th e range 100 to 600 m(3) per hour. It is strongly recommended that appr opriate temperature monitoring systems be fitted on all vehicles.