Pig Farrowing Nest Behavior and Welfare

Nest building is a powerful behavioral drive in sows approaching farrowing. Providing nesting materials improves welfare and reduces piglet crushing in loose-housing systems.

Key Facts

Wild and feral sows walk up to 8 km to find suitable nesting material before farrowing
Nest building behavior peaks in the 12-24 hours before birth and is driven by strong hormonal signals
Sows deprived of nesting material show elevated stress hormones and increased restlessness
Provision of straw or other materials reduces piglet mortality by improving positional behavior during farrowing
EU regulations now require nest-building materials for gestating and farrowing sows
Farrowing crates prevent nest building entirely — a significant welfare compromise

Welfare Considerations

The motivation to build a nest before farrowing is so strong that sows without materials perform vacuum nest-building on bare floors — repeated, frustrated movements that provide no function. This behavioral frustration represents a clear welfare harm. Straw provision allows sows to fulfill this drive, reduces pre-farrowing cortisol levels, and improves maternal behavior after birth. Free-farrowing systems that combine nest provision with sufficient space achieve comparable or better piglet survival rates to farrowing crates while dramatically improving sow welfare.

What You Can Do

Choose pork certified under schemes requiring farrowing enrichment and nest materials
Support legislation mandating nest-building materials for all farrowing sows
Advocate for investment in free-farrowing system design to make them economically viable
Reduce demand for low-welfare pork from systems that provide nothing to farrowing sows