Effect of preliminary bathing on adaptation of Aigamo ducklings to water

The present study was aimed to elucidate the significance of preliminary bathing of artificially hatched Aigamo ducklings which had been conventionally done under the rice-duck farming system. The effects of preliminary bathing on the bathing ability, the developments of plumage and uropygial gland and behavior of Aigamo ducklings were investigated. Daily 10-min. preliminary bathing for the ducklings after hatching was forcibly performed for preliminary bathing treatment (PBT) group. Body temperature of the control group after bathing for 15 min. markedly decreased with advancing age from hatching to 10 d of age, but it tended to increase afterward. By contrast, the body temperature of the PBT group after bathing for 15 min. was gradually decreased from 2 to 12 d of age, but it did not show such a large variation in PBT group as that in the control did. In addition, the body temperature of the PBT group was significantly higher than that of control group from 4 to 22 d of age (P0.05). Although the change in bathing time of the PBT group over time was similar to that of control, the bathing time was significantly longer in PBT than in control from 4 to 22 d of age (P0.05). Contour feathers of the PBT and control groups started to grow at 12 and 18 d of age, respectively. However, the newborn feathers were broken at 14 and 22 d of age, respectively. The down of the PBT group was significantly longer than that of the control except for 28 d of age (P0.05). The uropygial gland of the PBT group had significantly higher crude fat content than that of control at 14 and 21 d of age (P0.05). The PBT group spent more time in preening and less time in exploratory behavior than control significantly at 7 and 21 d of age (P0.05). In conclusion, preliminary bathing for Aigamo ducklings after hatching advanced the development of contour feathers and uropygial gland 1-2 weeks. Thus, the ducklings were able to have homeothermy and higher waterproof ability, and their bathing ability was eventually enhanced. Therefore, preliminary bathing can advance the date of free-ranging of the ducklings into paddy field by a week.