綜述所述，雙層圈舍似乎對豬只的行為（根據群間打斗行為）有積極的影響，并且圈舍容量的增加似乎讓豬只更加鎮靜。然而，仍需進一步開展雙層圈舍飼養更大體重豬只的試驗，以此來探究這些額外空間在達到最低的空間需求量方面是否完全有價值。
A two-level pen for fattening pigs: Effects on behavior, performance, and post slaughter measurements
A. Bulens , S. Van Beirendonck, J. Van Thielen, N. Buys and B. Driessen
Concurrent with a tendency toward higher slaughter weights of fattening pigs, minimum requirements for space allowance are increasing. Allowing pigs more space in existing standard pens, however, leads to a decrease in the number of pigs per pen, which jeopardizes the economic viability of the pig farm. A possible solution includes creating a two-level pen by constructing a second level in an existing pen, to enable an increase in space allowance per pig with the same number of pigs. We investigated the effect of such a pen on the behavior, performance, and post slaughter results of fattening pigs during the entire fattening period (30 to 110 kg). A total of 444 pigs were distributed over standard control pens (0.74 m2/pig) and two-level pens (0.99 m2/pig). Feed was provided only in a trough at the ground level of the pen. The results show that the increased space allowance and choice of levels in two-level pens influenced the pigs’ behavior in a positive way, as they performed less manipulation of pen mates (P< 0.0001). Moreover, pigs lay down more (P = 0.0007) and showed less head knocking (P = 0.005) in two-level pens, suggesting that they were calmer. In line with the behavioral results, pigs in two-level pens had fewer lesions on tails (P = 0.006), ears (P = 0.008), and shoulders (P = 0.01). Growth performance was not affected (P > 0.05), but post slaughter measurements revealed fewer livers with white spots in pigs from two-level pens. This result might be related to lower disease pressure in pens with lower stocking densities. In conclusion, a two-level pen seemed to have positive effects on the behavior of pigs (in terms of pen mate manipulation) and the increase in space allowance seemed to make the pigs calmer. The use of the second level by heavier pigs should, however, be further studied to investigate whether this extra space could be fully counted for the minimal space requirements.