Weaning piglets too early causes immune deficiency, behavioural problems, and stress for both piglets and sows, with welfare implications extending throughout the production cycle.
Early weaning imposes acute stress on piglets that are developmentally unprepared for separation. The immune system of a 3-week-old piglet depends significantly on maternal antibodies; abrupt weaning exposes piglets to pathogens before their own immune systems are fully functional. The resulting post-weaning diarrhoea causes suffering and drives antibiotic use. Behaviourally, early-weaned piglets show persistent belly-nosing — a frustrated rooting behaviour directed at littermates in the absence of the sow — indicating unresolved suckling motivation. Extending weaning age to at least 5 to 6 weeks improves piglet immune competence, reduces medication requirements, and results in better long-term behavioural development. The welfare case for later weaning aligns with the economic case for reduced disease burden.