Evaluating Thermal Comfort of Broiler Chickens during Transportation Using Heat Index and Simulated Electronic Chickens.

摘要

Broilers experience high physiological stress during pre-slaughter transport, especially under extremes of thermal environment. Characterization of thermal environment on the trailer is crucial to identify stress-prone regions during transportation. At the same time, Broilers experience high physiological stress during pre-slaughter transport, especially under extremes of thermal environment. Characterization of thermal environment on the trailer is crucial to identify stress-prone regions during transportation. At the same time, quantification of heat loss of the broilers loaded on trailers is important in understanding the well-being of the broilers. We have developed four electronic chickens (E-chickens) to simulate the sensible heat loss of live broiler during transit and holding period in commercial live-haul trips. It is an average broiler-sized enclosure with a thermostatically controlled circuit to keep the internal temperature at 41°C. Power consumption as a result of four different combinations of covering the enclosure as well as their sensitivity with exposed wind were compared. Double layer of fleece fabric was selected as the insulation cover for the E-chickens to match the sensible heat production reported in literature. Heat loss exhibited a positive correlation with the wind and a negative correlation with the temperature gradient between internal and external environment. However, the wet cover of E-chickens did not increase heat loss compared to dry cover, indicating its inability to release moisture unlike evaporation from natural feathers and respiratory water loss. Thirty-two commercial live-haul trips were monitored to determine humidity ratio increase-above-ambient air humidity, E-chickens were installed in eight of the trips. Moderate levels of measured power consumption of the E-chickens suggested that ambient temperatures in the range of 11°C-25.1°C (during transit) and 5.3°C-21.7°C (during holding) were in the zone of thermal comfort (allowing the live chickens to regulate heat by their metabolism to stay comfortable). For the holding period, the winter trips were mostly in the zone of thermal comfort, but during summers, hyperthermic conditions were widespread during transit. Fan-assisted evaporative cooling during on-farm loading may have introduced additional cooling due to wetting of live chicken surface, not quantified by the limitation of E-chickens. The mild weather observed during spring and fall season was the most comfortable for broilers.