Effects of modulating space density via the number of pigs in a pen on feeder use and feeder access in the finishing period

High stocking density can affect how finishing pigs access and use feeders. This study investigated how different space allowances, achieved by varying the number of pigs per pen, influenced feeder use and obstruction during the finishing period. A total of 197 pigs were assigned to one of three treatments: CON (18 pigs/pen, 0.7 m²/pig, n = 6 pens), SP9 (9 pigs/pen, 1.4 m²/pig, n = 6), and SP6 (6 pigs/pen, 2.8 m²/pig, n = 6). Each pen had one feeder with three headspaces. At weeks 2, 5, and 10, videos were recorded between 14:30 and 16:30 and scan-sampled every 20 seconds. Feeder use was defined as a pig with its head inside a headspace; feeder obstruction as a pig sitting or lying in front of a headspace, blocking access. Queuing was also recorded. Absolute feeder use was higher in CON than in SP9 and SP6 (P < 0.01), although use across the afternoon did not differ clearly between treatments. However, feeder obstruction was significantly more frequent in CON, particularly at week 10 (P < 0.01), with up to 75% of observations showing all headspaces blocked. Queuing was rare but mostly observed in CON. Across treatments, pigs preferred the outer headspaces (P < 0.01), while obstruction occurred most often near the solid floor (P < 0.01). In conclusion, high stocking density increases feeder obstruction, especially in later finishing stages. Reducing pig numbers per pen may improve access, but further refinement of pen and feeder design is recommended.