Physiological stress and welfare of broiler chickens in transit: solutions not problems!

Abstract

The rearing of large numbers of broiler chickens at geographically dispersed sites means that they have to be transported by road, over various distances, to centralized processing plants for slaughter. The birds may be exposed to a variety of stressors during transit, including the thermal demands of the transport microenvironment. The thermal environments experienced by broiler chickens during routine transport in the U.K. on a large number of commercial vehicles under a wide range of external climatic conditions have been characterized using three-dimensional thermal mapping (temperature and water vapor density). Inadequate ventilation results in heterogeneous distributions of temperature and humidity and, thus, thermal loads within the vehicle, and, therefore, the existence of a "thermal core" in which the risk of heat stress is increased. Relationships between specific physiological indices of stress and quantified thermal loads have been determined in accurate transport simulations in the laboratory. The findings have been employed to establish a predictive model of the induction of heat stress during commercial transportation, as well as to define the acceptable ranges and limits for temperature and humidity within the transport containers. These principles have been utilized in developing a monitoring system to warn of impending heat stress and in improving vehicle design to facilitate the prevention of heat stress during broiler transportation.

Injury and mortality in broilers during handling and transport to slaughter

“…In extremely cold conditions this temperature rise can be beneficial in that it raises the internal temperature above the potentially lethal cold external temperature. However, in a closed or partially closed ventilation configuration, internal thermal cores consisting of pockets of raised temperature and moisture from the birds can occur at one or more locations within the vehicle (Kettlewell et al 1993;Mitchell and Kettlewell 1998;Burlinguette et al 2012). If the internal temperature and humidity within areas in the core of the vehicle rises too high, some of the birds can experience hyperthermia that can be severe enough to cause mortality, even though the external temperature is so low that it would otherwise have caused hypothermia (Hunter et al 1997;Mitchell and Kettlewell 1998).…”

“…However, in a closed or partially closed ventilation configuration, internal thermal cores consisting of pockets of raised temperature and moisture from the birds can occur at one or more locations within the vehicle (Kettlewell et al 1993;Mitchell and Kettlewell 1998;Burlinguette et al 2012). If the internal temperature and humidity within areas in the core of the vehicle rises too high, some of the birds can experience hyperthermia that can be severe enough to cause mortality, even though the external temperature is so low that it would otherwise have caused hypothermia (Hunter et al 1997;Mitchell and Kettlewell 1998). In a 'closed' ventilation configuration, the air entering the vehicle through air inlets is at the low external temperature and might be accompanied by moisture and excessive air movement.…”

Animal health aspects of adaptation to climate change: beating the heat and parasites in a warming Europe

“…It may be proposed that the thermal micro-environment within the transport containers or vehicles is extremely vulnerable to changes in external thermal conditions. As such, in response to any potential increase in thermal load it poses the greatest threat to the animals' welfare and well-being (Appleby and Lawrence, 1999;Mitchell and Kettlewell, 1998;Cockram and Mitchell, 1999;Mitchell, 2006). Adverse thermal conditions resulting in either heat or cold stress may lead to reduced welfare, overt tissue damage or injury and increases in mortality in transit (Mitchell, 2006;Mitchell and Kettlewell, 2006;Mitchell and Kettlewell, 2008).…”

Manejo pré-abate de transporte e banho sobre a incidência de mortalidade de frangos de corte

“…Durante o transporte, os frangos ficam expostos a uma variedade de agentes estressores, como aceleração, vibração, impactos, jejum alimentar e hídrico, mistura social, perturbações e ruídos, além do microambiente térmico que se forma entre as aves (MITCHELL; KETTLEWELL, 1998;NICOL;SCOTT, 1990, SIMÕES et al, 2009a, 2009b. O transporte causa desde leve desconforto, com alterações na qualidade final da carne, até a morte dos animais.…”