Effects of Enrichment Type, Presentation and Social Status on Enrichment Use and Behaviour of Sows with Electronic Sow Feeding

Abstract

The goal of this study was to identify practical enrichments for sows in partially or fully slatted pen systems. Four treatments were applied: (1) Constant: constant provision of wood on chain; (2) Rotate: rotation of rope, straw and wood enrichments; (3) Stimulus: rotation of enrichments (as in Rotate) with an associative stimulus (bell or whistle); and (4) Control: no enrichment, with each treatment lasting 12 days. Six groups of 20 ± 2 sows were studied from weeks 6 to 14 of gestation in pens with one electronic sow feeder. Each group received all treatments in random order. Six focal animals (3 dominant and 3 subordinate) were selected per pen using a feed competition test. Digital photos were collected at 10 min intervals for 8 h (between 8 a.m. and 4 p.m.) on 4 days/treatment (d 1, 8, 10 and 12) to record interactions with enrichment. Skin lesions were assessed on days 1 and 12, and saliva cortisol samples collected in weeks 6, 10 and 14 of gestation on focal pigs. Sows spent more time in contact with enrichments in Rotate and Stimulus treatments than Constant. Enrichment treatments did not influence lesion scores. Subordinate sows spent more time standing and near enrichments than dominants. Subordinate sows also received more skin lesions and had higher salivary cortisol concentrations than dominants. These results indicate that access to enrichment is valued by sows but can result in greater aggression directed towards subordinates.

Short-Term Impact of Point-Source Enrichment on the Behavior of Gestating Sows Housed in Groups

“…Though the majority of focal sows (85%) interacted with the enrichment on day 1, their interest in enrichment had decreased sharply by the second day. Sows are more likely to remain interested in point-source enrichment if a rotation between objects of different natures is provided (Roy et al, 2019). However, sows' interest in the enrichment rebounded slightly after the second day of enrichment provision, a pattern consistent with another study in which sow play behaviors were highest 4, 7, and 20 days after the day of enrichment provision (Greenwood et al, 2018).…”

“…Environmental enrichment, as a (theoretically) desirable resource, can increase competition pressure (Van De Weerd and Ison, 2019), especially if individuals must compete for access to enrichment, for example if the enrichment is provided in insufficient quantities or is otherwise not accessible to all members of the group (Van de Weerd et al, 2006). Indeed, higher levels of aggression between conspecifics have been observed upon enrichment provision (Stewart et al, 2008;Roy et al, 2019). In the present study and similarly to Greenwood et al (2018), neither provision nor removal of the point-source enrichment had any impact on expression of agonistic behavior among focal sows.…”

Effects of Enrichment Type, Presentation and Social Status on Enrichment Use and Behavior of Sows—Part 2: Free Access Stall Feeding

“…In contrast, enrichment materials that are fixed to specific positions in the pen (point source object enrichment) can be used successfully in pens with slatted floors. Some materials that have been studied are rubber toys, pieces of wood, chains, and even garden hoses [ 10 , 11 , 12 , 13 ] as well as straw or hay [ 1 , 5 , 10 ] and the use of pheromones [ 6 ].…”

“…Another factor influencing enrichment use is habituation, which has been shown to greatly affect point source enrichments [ 10 , 11 , 16 ], as animals are less interested if the same material is repeatedly used [ 17 ]. Interaction with point source enrichment is high in the first 24 h and reduces over time [ 6 ].…”

“…Two common feeding management systems in group housing are Electronic Sow Feeding (ESF) and Free Access Stalls (FAS) [ 18 ]. It is likely that different feeding systems influence enrichment use in different ways to impact sow welfare, particularly in relation to aggression [ 10 , 18 , 19 , 20 ] and health risks such as lameness, injury and abortion [ 21 ]. A previous study by Roy et al [ 10 ] focused on the effects of enrichment in an ESF system; when enrichment was provided, the level of enrichment use was similar for dominant and subordinates sows, but subordinate sows showed greater general activity levels, increased injury scores and higher salivary cortisol levels.…”