Summary
During road transportation, livestock are subjected to a number of concurrent potential stressors that can increase mortality and morbidity and compromise welfare status and production efficiency. A major concern is the thermal micro-environment within the vehicle with both heat stress and cold stress constituting major problems. It is possible to mitigate the effects of external climatic conditions by improving vehicle design and operation using engineering solutions that match 'on-board' environmental conditions with the biological requirements of the animals. This review describes an investigative approach that targets four elements. These are the thermal conditions on commercial transport vehicles under a range of climatic conditions, the 'thermal comfort zones' or target conditions for different livestock species, the heat and moisture loads upon vehicles that must be dissipated and the thermodynamic characteristics of animal transport vehicles that affect the design of mechanical or active ventilation systems able to function at maximum efficiency under everyday commercial conditions. Results of research around these four elements can provide the sound scientific basis for improved vehicle design and operation and for legislation and codes of practice aimed at optimising animal welfare and productivity in relation to transportation of livestock on journeys of both long and short duration.