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.

Effect of microclimate temperature during transportation of broiler chickens on quality of the pectoralis major muscle.

This study investigated the effect of microclimate temperature during preslaughter transportation on chicken meat quality. Ninety broilers per load of 2,900 were monitored individually during 3 to 4 h of preslaughter transport in an actively ventilated trailer. Six transport test runs were conducted at average ambient temperatures of -27, -22, -17, -5, +4, and +11 degrees C. Birds were classified into 4 groups based upon the temperatures recorded in their immediate surroundings as follows: -16 to 0, 0 to 10, 10 to 20, and 20 to 30 degrees C. Internal body temperatures of the birds were recorded using Thermocron DS1922L iButtons. Birds were slaughtered in a commercial facility and meat quality of the chilled carcasses was evaluated by determination of pH, color, drip loss, thaw loss, cook loss, shear force, water-binding capacity, and pellet cook yield of the pectoralis major muscle. The breast meat from birds exposed to temperatures below 0 degrees C showed a significantly higher (P < 0.05) ultimate pH. Breast meat from birds exposed to temperatures below 0 degrees C showed significantly higher (P < 0.05) ultimate pH, a* value, water-binding capacity, and pellet cook yield and a significantly lower L* compared with breast meat of birds exposed to temperatures above 0 degrees C. The average core body temperatures were significantly lower (P < 0.05) during transport for birds exposed to temperatures below 0 degrees C compared with those exposed to temperatures between 0 and 10 degrees C. The latter birds had significantly lower (P < 0.05) core body temperatures compared with those exposed to temperatures above 10 degrees C. Thaw loss was significantly higher (P < 0.05) for breast meat of birds exposed to temperatures above 20 degrees C during transportation. There was no significant trend for b* value, drip loss, cook loss, or shear values based on environment temperature immediately surrounding the birds. Exposure to temperatures below 0 degrees C increased the incidence of dark, firm, and dry breast meat and decreased the incidence of pale, soft, and exudative breast meat. These results demonstrate that preslaughter transport may influence breast meat quality characteristics of broiler chicken.