Weaning is a time at which many different stressors are imposed on the piglet and poor health and performance are significant commercial problems. It is therefore important to understand which factors influence a piglet's adaptation to weaning, and how this might be improved. UK national recording scheme data demonstrate consistently better post-weaning performance for piglets from outdoor breeding herds than for indoor-bred piglets. There are many differences between the outdoor and indoor situation, and these are being systematically investigated. One potential difference which might influence the response to weaning is the greater degree of environmental and social diversity typically experienced by outdoor piglets during lactation.

Fifty-four sows and their litters were allocated according to farrowing date and parity to one of three enrichment treatments: treatments were (1) Control (C) in which litters remained in fully slatted farrowing pens with crates throughout lactation, (2) Socially enriched (SE) in which two adjacent litters were allowed to co-mingle from 12 days of age by removal of the dividing partition, and (3) Environmentally enriched (EE) in which piglets in similar housing were presented with a variety of small moveable objects and a rooting substrate.