Heat and moisture production by broilers during simulated cold weather transport.

To ensure broiler welfare during winter transport, it is necessary to manage heat and moisture accumulation within the transport vehicles. Hence, it is necessary to determine heat production (HP) and moisture production (MP) rates under representative conditions. An environmental chamber containing a standard transport drawer was used. Cold air was drawn from outside the building, warmed to the desired temperature, and passed through the drawer at 0.35 m(3)/s. Broilers were fasted for 7 h, placed into the drawer, and exposed to test conditions within the chamber for 3 h. Air temperature and RH were measured upstream and downstream of the insulated bird compartment at 1-min intervals. Differences in the paired temperature and RH values were used to calculate sensible HP and MP for each 1 min of confinement. Effects of temperatures between -8 and -18°C and a control (+20°C) were measured for birds in 2 conditions. In condition A, there were 15 birds/drawer. Birds were 32 to 33 d old and weighed 1.8 kg. Packing density was approximately 27 kg/drawer (31 kg/m(2)). In condition B, there were 19 or 22 birds/drawer. The drawers with 19 birds contained birds that were 39 to 40 d old that weighed 2.68 kg. In the drawers with 22 birds, the birds were 35 to 36 d old and weighed 2.29 kg. In either case, the packing density was approximately 50 kg/drawer (59 kg/m(2)). Thus, the birds in condition B were bigger, more numerous, and more tightly packed than the birds in condition A. Drawers were balanced for sex. At +20°C, HP and MP rates were similar to other published values. However, for both conditions, HP and MP rates increased with decreasing exposure temperatures. In condition A, HP was 6.08 ± 0.43 W/kg and MP was 4.46 g/h per kg at 20°C compared with 87.5 ± 10.3 W/kg and 22.08 ± 5.05 g/h per kg at -15°C. In condition B, HP was 8.12 ± 1.24 W/kg and MP was 5.53 ± 1.68 g/h per kg at 20°C compared with 45.92 ± 1.95 W/kg and 12.33 ± 0.22 g/h per kg at -18°C.