The aim of this article is to report on the expert opinion regarding the provision of environmental enrichment for pigs. A questionnaire was sent to 53 pig welfare scientists who were asked to specify which enrichment materials they considered sufficient to ensure pig welfare; 68% responded.
89% stated that providing a chain was not sufficient, while 84% stated that the provision of straw could be sufficient. 'Sustained animal-material interactions', 'rootability', 'manipulability' and 'chewability' were the main material properties referred to as being required for enriching
pig pens. Areas of further research suggested by the respondents encompassed both fundamental and applied research, including preference tests and demand studies, deprivation studies and quantitative studies to determine cut-off points. A case is made for modelling the available knowledge
to help close the gap between what is known in science and what is decided in society regarding animal welfare and environmental enrichment for pigs.