Commercial pig farming typically weans piglets at 3-4 weeks of age, far earlier than natural weaning. The welfare implications of early weaning and the effects of extending it are increasingly researched.
Early weaning causes acute distress in both sows and piglets through sudden separation from the social and nutritional bond. Piglets weaned at 3 weeks are physiologically and behaviorally immature for independence. The belly-nosing stereotype that develops in early-weaned piglets - nosing directed persistently at pen mates' abdomens - reflects a continued drive to nurse that cannot be satisfied. Post-weaning diarrhea, which increases with earlier weaning, causes illness and suffering in piglets while driving antibiotic use that contributes to resistance. The welfare comparison between 21-day and 28-day weaning consistently favors later weaning with fewer stereotypies and better health outcomes. Extended weaning to 5-6 weeks produces further welfare benefits but requires management changes that reduce throughput.