On-farm pig mortality is both a welfare indicator and a measure of system quality. High mortality rates signal systemic welfare problems that affect survivors as well as animals that die.
On-farm pig mortality is simultaneously a welfare harm in itself and a sensitive indicator of broader system welfare quality. Pigs that die from disease, injury, or management failure have experienced suffering before death. The farms and systems with highest mortality also consistently show worse welfare outcomes across other measures — lameness, tail biting, respiratory disease prevalence — reflecting systemic management quality. Pre-weaning mortality is particularly high in intensive systems: crushing by the sow, starvation through inadequate milk access, hypothermia, and congenital defects contribute to losses that represent both direct suffering and system failure. Welfare outcome monitoring programmes that use mortality as a key performance indicator and trigger investigation and intervention have demonstrated significant mortality reduction — showing that systematic attention to welfare indicators translates into real welfare improvement.