Rooting is the defining behavior of pigs, occupying over half their active time in natural conditions, and its frustration in confinement causes significant welfare harm.
The frustration of rooting motivation in barren environments causes redirected behaviors including tail biting, aggression, and stereotypies. These are not incidental problems but predictable consequences of housing that contradicts the most fundamental behavioral drives of the species. Providing rooting substrate is among the simplest and most impactful welfare improvements available.