Many different physiological changes have been observed in wild waterfowl during the flightless stage of wing moult, including a loss of body mass. Previously we established that captive barnacle geese (Branta leucopsis) underwent this characteristic decrease in body mass during their wing moult, even though they had unlimited and unrestricted access to food. In the present study we aimed to determine if this body mass loss during moult comprised mainly a reduction in fat stores, and to ascertain if the captive geese undergo pre-migratory and pre-winter fattening over a similar temporal scale to their wild conspecifics. The non-destructive technique of deuterium oxide isotope dilution was employed to provide repeated measurements of estimated fat deposition from a captive flock of fourteen barnacle geese. Birds were injected with deuterium oxide at 7 distinct intervals for one annual cycle. During the flightless period of the moult, body fat decreased by approximately 40% from the pre-moult value. During late-September and early October, body fat reached its highest point in the annual cycle, both as an absolute value and as a percentage of total body mass. We propose that while the energetic cost of wing moult is not the ultimate cause of fat loss in moulting barnacle geese, the approximate 212 g of fat catabolised during moult would provide sufficient energy to cover the cost of the replacement of the flight feathers, estimated to be 6384 kJ, over an approximate 42 day period. We conclude that the previously recorded increase in metabolism during moult in the geese, led to the use of endogenous fat reserves because the birds reduced rather than increased their food intake rates owing to the increased risk of predation when flightless. We also conclude that captive barnacle geese do undergo pre-winter and pre-migratory fattening, providing further evidence of the innate nature of these fat deposition cycles.

中文翻译：

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翅膀换羽前的冬季增肥和脂肪损失：圈养的藤壶鹅（黑雁）中的脂肪沉积的年度循环

在翅膀蜕变的非飞行阶段，野生水禽已观察到许多不同的生理变化，包括体重下降。先前我们建立了圈养的藤壶鹅（黑雁）即使没有任何限制也没有限制地获得食物，但在翅膀换羽期间体重却出现了这种特征性下降。在本研究中，我们旨在确定蜕皮过程中这种体重减轻是否主要包括减少脂肪存储，并确定圈养的鹅是否在与野生同种相似的时间尺度上进行了迁徙和冬季前的育肥。氧化氘同位素稀释的非破坏性技术被用来重复测量从十四只藤壶鹅的圈养群中估计的脂肪沉积。每年以7个不同的时间间隔向家禽注射氧化氘。在换羽期中，体内脂肪比换羽前减少了约40％。在9月下旬至10月初，人体脂肪以绝对值和占总体重的百分比达到年度周期的最高点。我们建议，虽然换羽的高能成本不是蜕皮雁脂肪损失的最终原因，但换羽过程中分解代谢的212 g脂肪约能提供足够的能量，以弥补更换飞羽的成本，估计在大约42天的时间内为6384 kJ。我们得出的结论是，以前记录的鹅换羽过程中新陈代谢的增加导致了内源性脂肪储备的使用，因为由于飞行时捕食的风险增加，鸟类减少而不是增加食物的摄入量。我们还得出结论，圈养雁确实会在冬季前和迁徙前进行育肥，