Environmental Enrichment for Sucker and Weaner Pigs: The Effect of Enrichment Block Shape on the Behavioural Interaction by Pigs with the Blocks

SIMPLE SUMMARY: How often do intensively-housed pigs interact with enrichment devices, especially smaller pigs during the sucker and weaner phases of production? Understanding whether smaller pigs use such devices, whether habituation occurs, and whether device-shape influences the level of interaction by pigs are all relevant questions surrounding justification for including enrichment devices in pig pens. We provided litters of pigs from 10 to 60 days old with one of three different shaped enrichment blocks (cube, brick, or wedge) and recorded oro-nasal contact with the blocks on two days each week. Fresh blocks were provided weekly. While pig interaction with blocks was infrequent before about 25 days of age, contact with the blocks steadily increased thereafter. Brick-shaped blocks were used more than the other shapes, possibly because the brick-shape presented a wider surface for contact, allowing multiple pigs to simultaneously interact with the block. Pigs interacted more with 1-day-old (i.e., ‘fresh’) than 4-day-old blocks, suggesting that habituation to the blocks may have occurred. ABSTRACT: This experiment tested the effect of enrichment-block shape on oro-nasal contact by young pigs, and possible habituation to the blocks. Nineteen litters (197 piglets) were randomly allocated to one of three block-shape treatments: Cube, Brick, or Wedge. Oro-nasal contact with blocks was infrequent before 25 days of age. Thereafter, contact steadily increased, suggesting enrichment blocks may not need to be provided until week 4 of lactation. Brick-shaped blocks attracted more oro-nasal contact than the cube and wedge shapes (p = 0.002). Oro-nasal contact was more frequent (p < 0.001) during the first 24 h after block introduction than when blocks were four days old. From 25 to 60 days of age, oro-nasal bouts were longer (p = 0.014) during the first 30 min of exposure to a fresh block, than for the remainder of the 24 h, or on day 4 after block replacement. Therefore, habituation to blocks may have occurred by 24 h after block introduction. Brick-shaped blocks may present a wider surface for oro-nasal contact, where multiple pigs could simultaneously interact with the block. We speculate that simultaneous interaction with brick-shaped blocks may be similar to a litter co-operatively massaging the sow’s udder prior to suckling bouts.