How providing appropriate substrate and bedding materials to pigs at all life stages improves welfare by satisfying natural rooting and nesting behaviors.
Substrate provision is one of the most fundamental and most neglected welfare interventions in commercial pig production. The drive to root and manipulate substrate is among the strongest behavioral motivations in pigs — it is not simply a preference that can be satisfied by alternatives, but a deeply embedded behavioral need shaped by millions of years of evolution. When this drive cannot be expressed on appropriate materials, pigs redirect it to penmates, causing tail biting and ear biting, or express it as stereotyped bar-rooting on barren surfaces. The addition of even small quantities of straw or other manipulable material dramatically reduces these problem behaviors. Regulatory minimum enrichment requirements that permit hanging chains as alternatives to rooting substrate fail to meet this species-specific behavioral need.