Nest-building is a powerful motivational drive in sows that is systematically frustrated in most commercial farrowing systems. Providing nesting materials dramatically improves sow welfare.
Nest-building frustration is one of the most clearly documented welfare failures in commercial pig production. Research using preference tests, motivational studies, and stress biomarkers consistently shows that the drive to build a nest before farrowing is a fundamental behavioral need in sows — one that industrial systems routinely fail to provide for. A sow unable to nest-build in the hours before birth shows clear behavioral signs of distress: repetitive rooting at the floor, restlessness, and elevated cortisol. The tragedy is that providing nesting materials is simple and inexpensive. Even small quantities of straw or hay provide a meaningful outlet for this drive and measurably improve sow welfare and productivity.