Weaning is one of the most stressful events in a pig's life, combining separation from the mother with social mixing, dietary change, and transport. The timing and management of weaning significantly affects welfare outcomes.
Weaning in pigs causes compounded welfare harm through the simultaneous removal of multiple sources of comfort and security: maternal contact, suckling behaviour, familiar social companions, familiar environment, and familiar diet. The resulting stress response is measurable through cortisol elevation, vocalisation, increased locomotion, and reduced lying time in the days following weaning. Post-weaning diarrhoea caused by E. coli infection exploits the immune suppression window and was historically treated with preventive antibiotics - a practice now restricted as part of antibiotic stewardship. Welfare-minimising weaning management includes keeping litter mates together (avoiding social mixing at weaning), providing familiar bedding material, offering creep feed before weaning to acclimatise piglets to solid food, and ensuring consistent pen temperature to avoid thermoregulatory stress on top of social stress.