Effects of environmental enrichment on behaviour, physiology and performance of pigs: A review.

The aim of this paper is to critically analyse and synthesise existing knowledge concerning the use of environmental enrichment and its effect on behaviour, physiology and performance of pigs housed in intensive production systems. The objective is also to provide clarity as to what constitute successful enrichment and recommend on when and how enrichment should be used. Environmental enrichment is usually understood as an attempt to improve animal welfare and to lesser extent, performance. Common enrichment objects used are straw bedding, suspended rope and wood shavings, toys, rubber tubing, coloured plastic keys, table tennis balls, chains and strings. These substrates need to be chewable, deformable, destructible and ingestible. For enrichment to be successful four goals are the prerequisite. Firstly, enrichment should increase the number and range of normal behaviours (2) prevent the phenomenon of anomalous behaviours or reduce their frequency (3) increase positive use of the environment such as space and (4) increase the ability of the animals to deal with behavioural and physiological challenges. The performance, behaviour and physiology of pigs in enriched environments is similar or in some cases slightly better when compared with barren environments. In studies where there was no improvement, it should be born in mind that enriching the environment may not always be practical and yield positive results due to factors such as type of enrichment substrates, duration of provision and type of enrichment used. The review also identifies possible areas which still need further research, especially in understanding the role of enrichment, novelty, breed differences and other enrichment alternatives.