Implementation of Straw Racks in Commercial Pig Housing—Impact on Straw Availability and Pig Behaviour

This study investigated if straw racks, which enable larger straw rations, induced a more straw-directed behaviour in pigs, as a mean to facilitate the provision of manipulable material and natural behaviour. It was conducted on a commercial farm (459 pigs, 42 pens, 30–120 kg) where half of the pens received 25 L of straw on the floor (CONTROL) and the other half of the pens received straw in a rack holding 44 L of straw (RACK). The pig behaviour in five randomly assigned pens per treatment were recorded for 24 h, during three periods of production. Pig activity levels, exploratory behaviour, pen utilization and available clean straw were scan sampled. During period 1, no pigs were observed interacting with the straw racks. During this period, CONTROL pigs conducted more straw-directed behaviour and less pen-directed behaviour compared to pigs in the pens with a rack during period 1. The lack of rack interactions may imply an underdeveloped spatial cognition in the pigs. Apart from period 1, there were no significant difference in behaviour between RACK and CONTROL pigs. The racks did not disturb the use of the pen. The absent treatment effect in periods 2 and 3 may reflect that there was a too small difference in straw ration between the treatments. In order to design and implement straw racks that promote straw interaction, future studies should focus on understanding pigs’ spatial cognition.