Pig Farrowing Nest Building: Natural Behavior and Welfare

The nest-building drive of sows before farrowing is a powerful behavioral need whose frustration causes significant distress in confined systems.

Key Facts

Wild sows spend 6-12 hours building elaborate nests before farrowing using grass, leaves, and branches
Nest building is driven by a hormonal surge in the 24 hours before birth and is species-typical
Sows in farrowing crates cannot perform nest building movements and show repetitive frustration behaviors
Providing even limited nesting material like jute sacks reduces distress and improves maternal behavior
Free farrowing systems that allow nest building show improved sow welfare and similar piglet mortality to crates
The welfare case for providing nesting material is so strong that EU legislation now requires it

Welfare Considerations

Frustration of the nest-building drive causes measurable distress in sows that can be observed in repetitive stereotypic movements and elevated stress hormones. This behavioral need is not a minor preference but a powerful pre-partum drive. Providing nesting material is a low-cost intervention with significant welfare benefit for one of the most important behavioral events in a sow's life.

What You Can Do

Support pork certification schemes requiring nesting material provision before farrowing
Advocate for legislative requirements for nesting material in all farrowing systems
Choose pork from farms using free-farrowing or loose-housed farrowing systems
Support research into nesting material types that work within existing housing constraints
Share information about sow pre-farrowing needs with people who eat pork without considering pig welfare
Donate to organizations campaigning for farrowing crate bans with appropriate transition periods