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

Abstract

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.

Effects of Early and Current Environmental Enrichment on Behavior and Growth in Pigs

“…Enrichment reduced aggression before, but not after weaning. Beattie and O'connell (17) found a reduction in aggression in pigs provided with extra space and rooting substrates, whereas studies comparing similar sized pens with or without rooting substrates reported either no effect (11,51), a decrease (57) or an increase in aggression (58,59). Thus, effects of enrichment on aggression seem inconsistent.…”

Animal Welfare and Production Challenges Associated with Pasture Pig Systems: A Review

“…Pastures are complex ecosystems where a great variety of elements and organisms interact. They are similar to the environments in which pigs evolved, and consequently better suited to fulfil their physiological and psychological needs than other systems [24,27]. Pasture and indoor-confinement rearing environments differ considerably and might generate differences in the welfare of pigs managed in those production systems.…”

“…Compared with other systems, pasture systems offer pigs a greater opportunity to carry out more physical activity [6], which would result in better animal welfare [35,108]. The impossibility of behaving naturally due to confinement, and the privation of environmental stimulation have been identified among the main causes of boredom and frustration in indoor managed pigs [24,39]. Additional potential consequences to lack of exercise are more health related: impairment of the cardiovascular system, and weakness of bones and muscles which frequently cause lameness [41].…”

Does Diversity Matter? Behavioural Differences between Piglets Given Diverse or Similar Forms of Enrichment Pre-Weaning

“…Provision of enrichment can prevent or reduce tail-directed behaviours [ 4 , 5 ], improve pigs’ emotional state [ 6 ] and improve pig performance [ 7 ]. In general, loose organic material, such as straw (from a handful to deep straw-bedding), is considered to be the gold standard.…”