Effects of species-relevant environmental enrichment on the behaviour and productivity of finishing pigs

Three different enrichment objects, which were designed according to pig-specific requirements, were provided to groups of growing pigs with undocked tails. The enrichment treatments were a substrate dispenser providing straw, a rootable feed dispenser providing flavoured feed and a liquid dispenser that provided flavoured water when chewable rods were manipulated. These objects were compared with a pen with a full bed of straw (positive control) and a commercial enrichment object, a Bite Rite (Ikadan System, Denmark, minimal enrichment). Video tape recordings from weeks 1, 3 and 7 were scanned using time-sampling to investigate general behaviour and enrichment use. Production parameters were measured, as well as occasions where tail biting (with fresh damage to a tail) occurred. The behavioural observations revealed that all of the enrichment provided was used by the pigs, but there were differences in the level and type of enrichment use by the pigs. The extent to which the straw and straw rack were used was significantly greater than for the other treatments (11.5 and 3.6% of the observations). Enrichment that was located on the floor could be manipulated from different postures, including whilst lying down; for example in 6.6% of the observations in which pigs on straw were lying down, they were manipulating the straw. This also applied, but to a lesser extent, to the straw rack and rootable feed dispenser. Groups provided with the liquid dispenser (which experienced technical problems) and Bite Rite had the highest prevalence of tail biting incidents (100 and 83% of pens, respectively). This study shows that a full bed of straw was the most successful way of occupying the pigs and, in addition, it prevented severe tail biting. Where it is not possible to supply a full bed of straw, point source enrichment objects such as substrate or feed dispensers appear to offer a good substitute. Such objects were well-used and did not affect production negatively; furthermore, severe outbreaks of tail biting were prevented.