Animal welfare is a major public concern because all farmed animals are thought to be sentient beings. Positive and negative aspects of the welfare of animals during transport should be assessed using a range of behavioural, physiological and carcass quality measures. Many of the indicators are measures of stress, involving long-term adverse effects, or indicators of pain, fear, or other feelings. Some of the key factors affecting the welfare of animals during handling and transport are: attitudes to animals and the need for staff training; methods of payment of staff; laws and retailers' codes; journey planning; traceability of animals; genetic selection; rearing conditions and experience; the mixing of animals from different social groups; handling procedures; driving methods; space allowance per animal on the vehicle; journey length; increased susceptibility to disease; increased spread of disease and the extent to which each individual can be inspected during the journey.