Rooting is one of the most fundamental pig behaviors and its deprivation in bare intensive systems causes significant frustration, stereotype development, and compromised welfare in billions of animals.
Rooting motivation is so fundamental to pig nature that pigs continue to perform rooting movements on bare concrete floors even when no substrate is present — a redirected behavior indicating frustration of a highly motivated drive. The provision of straw — perhaps the single most evidence-based pig welfare intervention — dramatically reduces abnormal behavior by providing an appropriate substrate for rooting, nesting, and oral manipulation. The cost of straw provision is modest relative to its welfare benefits, yet many intensive systems omit it because of slurry management complications in fully slatted systems. This represents a case where welfare improvement requires systemic housing design changes alongside materials provision.