The transition from farrowing crates to alternative farrowing systems is a central challenge in pig welfare reform.
Farrowing crate confinement causes severe welfare harm to sows during the critical periparturient period when their behavioral motivation for nest-building, movement, and maternal behavior is at its highest. Sows confined in farrowing crates cannot perform the nest-building behavior they are strongly motivated to carry out before birth, cannot turn around during or after farrowing, and cannot perform the distance control from piglets that prevents inadvertent overlying in natural settings. The stereotypic behaviors observed in crated sows indicate chronic frustration with movement restriction. Modern free-farrowing pen designs that include anti-overlying rails, deep straw bedding, piglet creep areas with supplemental heat, and sufficient space for sow turning have achieved overlying rates comparable to farrowing crates while meeting sow behavioral needs. The welfare case for transition to free farrowing is well established, and industry resistance based on piglet mortality risk is increasingly addressed by improved pen design evidence.