Welfare outcome indicators for pigs assess the animals themselves rather than just their housing, providing a more direct measure of how pigs actually experience their lives.
Welfare outcome indicators represent the gold standard of farm animal welfare assessment because they measure what actually matters: how the animal is experiencing its life. An empty, sterile, but spacious pen may score well on input measures but poorly on welfare outcomes if it fails to meet behavioural needs. Conversely, a well-managed system with high-quality litter, social stability, and good nutrition may achieve excellent welfare outcomes even if input metrics seem modest. For pigs, tail lesion scoring is particularly powerful: tail biting is a behaviour driven by frustration, stress, and unmet needs. High tail lesion prevalence is a reliable signal that the system is failing the animals. Routine WOI collection and benchmarking across farms would drive welfare improvement more effectively than input auditing alone.