Deep litter systems combining thick straw bedding with infrequent removal create conditions that allow pigs to express rooting behaviour naturally while providing thermal comfort and environmental complexity.
Deep litter systems represent one of the most comprehensive implementations of pig welfare improvement through environment design. Rather than providing token enrichment in a barren environment, deep litter systems transform the entire living environment into a rooting substrate — one that changes over time as it composts, providing novel smells, textures, and microbial diversity that engage pigs throughout their lives. The behavioural differences between pigs in deep litter and those on slatted concrete are striking and well documented: reduced stereotypy, lower aggression, more time spent in substrate manipulation, and better social integration. The barriers to adoption — straw availability, cost, and slurry system incompatibility — are real but not insuperable, and some of the most commercially successful higher-welfare pig producers in Europe operate deep litter systems at scale.