Abstract: We describe the process of coat in musk deer fawns（Moschus berezovskii）based on observations of captive individuals，and light and scanning electron microscopy（ SEM）of guard hair morphology. After birth，there are 2 complete molts in fawns from summer to the end of the year. The processes of summer and winter molting are similar，both beginning with the limbs and head and neck region，and then extending to the back and rump. Mean hair length of neonates was 26.5 mm，increasing to 37.5 mm and 48.7 mm，in summer and winter respectively. Mean hair width of neonates was 0. 136 mm shortly after birth，increasing to 0.276 mm and 0. 42 mm in summer and winter，respectively. All differences were significant（P < 0. 001）. Although the hairs had a similar medullar structure there was a large，irregular intercellular space within the medullae in winter hair. Length，width and hair structure of winter pelage were similar to that of adults.These results indicated that winter pelage of fawns had similar insulation characteristics to that of adults.

Key words: Coat changes, Insulation, Musk deer(Moschus berezovskii)fawn, Medullar structure

摘要：

关键词: 林麝幼体, 换毛序, 髓质结构, 隔热性能