Research on enrichment material effectiveness for pigs shows significant differences between manipulable substrates and simple hanging objects, with implications for welfare standards.
The distinction between nominal enrichment compliance and genuinely effective enrichment is critical to pig welfare outcomes. Regulations in the EU and other jurisdictions that require enrichment without specifying effectiveness allow facilities to meet the letter of the law with hanging chains that provide minimal behavioral benefit. Pigs quickly habituate to static, non-functional objects and return to barren-environment behaviors. Research consistently demonstrates that substrate materials - straw, peat, composts, or sand - that allow actual rooting, foraging, and investigation provide substantially greater welfare benefit than hanging objects. The welfare case for effective enrichment standards that specify manipulability and substrate options would prevent the widespread use of nominal enrichment that provides legal compliance without welfare benefit.