Changes in the mean FPD score among birds that were moved from the wet-litter house to the dry-litter house are shown in Fig. 3 (B). The mean FPD score of 15 birds selected at 21 days of age was 1.53 at the time of relocation. After relocation, the score started to decrease and was 0.88 at 49 days of age. Similar changes were observed among birds that were relocated at 28 days of age, and the FPD score decreased slightly, reaching 1.60 at 49 days. Among birds moved at 35 days of age, however, the FPD score was already high (2.40) at the time of relocation and thereafter showed a similar pattern to that of birds reared on wet litter only.