Weaning — the transition from sow's milk to solid feed — is one of the most welfare-significant events in the pig production cycle. The abrupt nutritional, social, and environmental changes associated with commercial weaning create a period of high disease risk and welfare challenge that requires careful management to minimize suffering.
The Welfare Challenge of Weaning
Commercial weaning typically occurs at 21-28 days of age, when piglets are removed from their mothers and moved into weaner accommodation with unfamiliar pen-mates. This simultaneous change in nutrition (milk to dry feed), social environment (familiar litter-mates to mixed unfamiliar groups), physical environment (farrowing pen to weaner building), and loss of maternal proximity creates acute stress that is well-documented by behavioral and physiological measures.
Post-weaning piglets show elevated cortisol, aggression during hierarchy re-establishment, reduced feed intake, and high susceptibility to post-weaning diarrhoea (PWD) — a significant welfare and mortality problem caused by pathogenic E. coli exploiting the digestive disruption and immune stress of weaning. The welfare costs of PWD include profuse diarrhoea, dehydration, electrolyte imbalance, and death in severe cases.
Weaning Age and Welfare
Later weaning ages reduce the severity of weaning stress: piglets weaned at 4-5 weeks are better immunologically and behaviorally developed than those weaned at 3 weeks, and show lower PWD rates and better immediate post-weaning performance. European regulations set minimum weaning ages at 28 days (with exceptions to 21 days under specific circumstances), reflecting the welfare scientific evidence for later weaning.
Feed Transition Management
Gradual dietary transition — using high-quality, palatable starter feeds that maintain feed intake through the weaning period — reduces the nutritional shock of weaning. Highly digestible protein sources, appropriate inclusion of milk products, feed additives that support gut health, and creep feeding before weaning (familiarizing piglets with solid feed while still with the sow) all contribute to welfare-positive nutritional transition management.
Social Environment at Weaning
Maintaining litter groups intact at weaning — rather than mixing piglets from multiple litters — reduces aggression during the post-weaning period. Familiar pen-mates require less hierarchy re-establishment fighting, reducing stress and injury. Where mixing is necessary for batch management, providing adequate space and enrichment materials during the mixing period reduces aggression severity.