Selective breeding can significantly reduce the prevalence of welfare-relevant traits in pig populations, from aggressive temperament to disease susceptibility and the ability to cope with farm environments.
Genetic selection represents a systems-level welfare intervention that addresses the root of welfare problems rather than managing their consequences: breeding pigs less susceptible to tail biting reduces both the behavior and the suffering of victims more effectively than management interventions applied to populations that are predisposed to the problem. The litter size example illustrates the unintended welfare consequences of selection for single traits - hyperprolific sows producing 15+ piglets may lack sufficient teats and milk for all offspring, creating competition and starvation among the smallest piglets. Modern genomic selection tools allow simultaneous optimization of multiple traits, reducing the likelihood of inadvertent welfare compromise. Industry adoption of welfare-relevant trait selection faces commercial pressures: production efficiency traits have clear financial return, while welfare-relevant traits may have less obvious immediate economic benefit.