Relationship between environmental enrichment and the response to novelty in laboratory-housed pigs

Environmental enrichment is the enhancement of the physical and/or social environment in which an animal lives with the goal to improve its quality of life. Our objective was to investigate the effect of provision of environmental enrichment in the home pen on responsiveness to novelty in laboratory housed pigs. Pigs were housed (4 pigs/pen) for three weeks in enriched (EE; n = 32) or barren/control (CON; n = 32) pens. Pigs were then tested in two anxiety behavioral tests; novel object (NOT) and human interaction (HIT) tests. Pigs were placed in a novel arena for a 5 minute (familiarization period, FAM), then either a novel object (NOT) or an unfamiliar human (HIT) was introduced for a 5 minute interaction period. Behavior in the home pen and during the NOT and HIT were determined through direct observations and video recording. In the home pen, EE pigs spent more time active and interacting with the environment, and CON pigs spent more time inactive and performing social interactions. In the NOT and HIT, EE pigs crossed more squares than CON during the FAM period, tended to freeze more and interact less with the novel object or person than CON pigs. In conclusion, EE pigs may experience more anxiety when exposed to novelty than CON pigs. Alternatively, CON pigs may be more motivated to interact with sources of novelty/enrichment during testing due to the lack of stimulation in the home pen.