Sows have a powerful instinctive drive to build nests before farrowing that is severely frustrated in conventional farrowing crates, causing significant behavioral stress during a critical welfare period.
The farrowing crate represents one of the most extreme confinements in modern agriculture, preventing sows from performing the nesting behavior that is among their strongest pre-partum motivations. A sow repeatedly rooting at bare concrete in a crate just wide enough to stand in is visibly expressing behavioral frustration with no outlet. Alternative systems including loose farrowing pens with nesting material demonstrate that piglet mortality — the primary justification for crates — can be managed through good stockpersonship without confining sows. The welfare case against farrowing crates is among the strongest available for any single livestock confinement practice.