Pig Weaning Stress: Welfare Science and Mitigation

Key Facts

• Commercial pigs are typically weaned at 21-28 days — far earlier than the 12-16 weeks natural weaning age
• Weaning combines simultaneous separation from the dam, mixing with unfamiliar pigs, and diet change
• Post-weaning diarrhea (PWD) caused by enterotoxigenic E. coli is the leading welfare and production problem
• Early weaned pigs show higher aggression, belly nosing, and ear biting than later-weaned counterparts
• Housing temperature, diet transition, and social grouping management significantly affect weaning outcomes

Welfare Considerations

Weaning stress has profound short-term welfare impacts: piglets experience hunger (as they adjust to solid food), anxiety from dam separation, fear from mixing with unfamiliar piglets, and pain from fighting injuries. Plasma cortisol levels spike at weaning and remain elevated for several days. Post-weaning diarrhea compounds suffering for many piglets. Longer lactation periods (28 days vs 21 days) consistently improve welfare outcomes with only modest production cost. Transitional diets with high palatability and gradual introduction of solid food from 2 weeks of age mitigate diet-change stress.

What You Can Do

• Advocate for longer lactation periods (28 days minimum) in welfare standards and legislation
• Introduce creep feed from 7-10 days of age to ease the transition to solid food at weaning
• Group same-litter pigs together after weaning to minimize aggression from unfamiliar mixing
• Maintain nursery temperature at 28-30C for newly weaned pigs — chilling compounds weaning stress
• Reduce reliance on zinc oxide for PWD prevention through improved housing and diet protocols