Pig Farrowing Nest Building and Welfare

The nesting instinct in sows before farrowing is a powerful behavioural drive whose suppression in intensive systems creates significant welfare costs.

Key Facts

Wild sows and free-ranging domestic pigs spend 6-12 hours constructing elaborate nests from grass, branches, and leaves before farrowing.
The nesting drive is hormonally mediated by declining progesterone and rising prolactin in the hours before birth.
Sows denied nesting materials show redirected behaviours including bar-biting, rooting at bare floors, and increased agitation.
Stress during farrowing from frustrated nesting behaviour is linked to prolonged labour and higher piglet mortality.
Providing even modest nesting material (straw, hemp) reduces pre-farrowing stress behaviours by up to 70% in studies.

Welfare Considerations

The frustration of the nesting drive is one of the most acute welfare problems in intensive pig production. Sows in bare farrowing crates cannot express this fundamental behaviour, leading to measurable physiological and behavioural distress. Evidence shows that providing nesting material — even in confined systems — dramatically reduces stress, shortens farrowing duration, and improves piglet survival, making it both a welfare and productivity improvement.

What You Can Do

Choose pork products certified to higher welfare standards that require nesting material provision.
Support campaigns advocating for mandatory nesting material in farrowing systems.
Share evidence about the welfare benefits of nesting material with farmers and in public discussions.
Donate to research on alternative farrowing systems that allow sow behavioural expression.