Vehicle design and thermal comfort of poultry in transit

Abstract

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 loads.

2. Data from two summer and two winter journeys on each of 5 naturally‐ and 2 fan‐ventilated vehicles were used to derive general equations to predict H and temperature lift for each vehicle.

3. From these, air movement, V, within the crates was calculated together with predicted H at ambient temperatures to compare the thermal comfort of the vehicles.

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 ambient. Poorly‐feathered hens were, consequently, extremely cold‐stressed in winter. When stationary, vehicles with a central passage that enabled the ‘stack effect’ to operate were thermally comfortable provided V was kept low. Designs stocked over die whole floor area of the vehicle 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‐warmed 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 pullets or broilers should be 10.15°C and near poorly‐feathered hens 22–28°C. Suitable ventilation rates are likely to be in the range 100 to 600 m³ per hour. It is strongly recommended that appropriate temperature monitoring systems be fitted on all vehicles.