Research on pig enrichment reveals that rooting substrate consistently outperforms manipulable objects in satisfying pigs' behavioural needs and reducing aggression.
The welfare case for rooting substrate is strong: pigs are highly motivated to root and explore, and thwarting this drive in barren environments leads to boredom, frustration, and redirected behaviours like tail-biting. Research by SRUC and Wageningen University demonstrates that pigs given deep straw bedding show lower cortisol levels, fewer injuries, and greater expression of positive welfare indicators. However, deep straw bedding is incompatible with slatted flooring systems used in many commercial units, creating a structural barrier to welfare improvement. Welfare legislation is increasingly moving toward mandatory deep litter requirements, with some countries including Norway already mandating access to rooting material.