Determination of vitamins D, A, and E in sera and vitamin D in milk from captive and free-ranging polar bears (Ursus maritimus), and 7-dehydrocholesterol levels in skin from captive polar bears

Publication Type:
 Journal Article
Year of Publication:
 1998
Authors:
 David E. Kenny, Nancy A. Irlbeck, Tai C. Chen, Zhiren Lu, Michael F. Holick
Publication/Journal:
 Zoo Biology
Publisher:
 A Wiley Company, Inc., Wiley Subscription Services
Keywords:
 , , , , , , ,
ISBN:
 1098-2361
Abstract:

Abstract 10.1002/(SICI)1098-2361(1998)17:4<285::AID-ZOO3>3.3.CO;2-4 The difference between serum levels from 36 captive and 56 free-ranging polar bears (Ursus maritimus) for 25-hydroxyvitamin D (25-OH-D) was found not to be significant (mean ± SD = 348 ± 215 nmol/L [captive], 360 ± 135 nmol/L [free-ranging], t = 0.30, df = 52.8, P = 0.76), whereas the difference for retinol and α-tocopherol was significant (retinol, 1.37 ± 0.67 μmol/L [captive] 1.89 ± 0.63 μmol/L [free-ranging], t = 3.88, df = 72.4, P <0.001, α-tocopherol, 18.56 ± 18.56 μmol/L [captive], 48.76 ± 13.92 μmol/L [free-ranging], t = 7.85, df = 61.9, P < 0.001). Due to the high fat content in the polar bear diet, seal blubber may be the source of these fat-soluble vitamins. Six skin biopsies were analyzed from captive polar bears at the Denver Zoological Gardens for 7-dehydrocholesterol levels and found to contain 0.11 ± 0.03 nmol/cm2. This finding also helps to support the contention that the source of vitamin D for polar bears may be ingestion and not cutaneous production. Vitamin D content in the milk from one captive sow in the den (0.14 nmol/g) and 10 free-ranging sows with cubs of the year out on the ice pack (0.0042 ± 0.0073 nmol/g) were also evaluated. It would be helpful to evaluate additional milk samples from denning and non-denning sows with cubs to see whether vitamin D content varies according to the stage of lactation. Zoo Biol 17:285–293, 1998. © 1998 Wiley- Liss, Inc.

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