A test of a free-access two-level pen for fattening pigs

Two prototype two-tiered pens were constructed for fattening pigs. The pens consisted of a solid or porous upper floor located 0-8 m above a slatted lower floor, with a short ramp joining the two levels. Food was available only on the upper level and water only on the lower. Eleven groups, each of 15 to 18 pigs were housed in the two-tiered pens for 8 weeks, starting at 10 weeks of age, while matched control groups were housed in a conventional pen offering the same amount of total floor space. During the 1st week, some pigs were slow to adapt to the two-tiered system and average weight gain was lower than in the control pen. Over the 8 weeks, however, weight gain and food conversion ratios were very similar in the two pen types. The animals made effective use of the two levels, and kept the upper level free from dung. Physical condition of pigs in the two-tiered pen was as good as, or better than, that of the controls. The two-tiered design offers several potential advantages in terms of animal production and behavioural problems.