Kerr, S. G. C., Wood-Gush, D. G. M., Moser, H. et al. 1988. Enrichment of the production environment and the enhancement of welfare through the use of the Edinburgh Family Pen System of pig production. Research and Development in Agriculture 5, 171-186.

Pigs in family pens [four sows with offspring in four pens each furnished with nest area, activity area, peat area, connecting faeces corridors, a familiar mature boar joining the group for a period from day 14 to day 56] exhibited the normal range and frequency of behaviour patterns and no abnormal behaviour was recorded. .. The high level of environmental complexity is provided by the various areas of the pen with several different substrates and solid divisions resulting in the areas being distinct and separate from each other. Thus the sow can remove herself from physical and visual contact with her piglets and will therefore regulate the visual stimulus of the piglets, with suckling frequency remaining unaltered. Further, sows are able to perform a diversity of other activities such as rooting, social interactions.