Metabolic and hormonal changes during the molt of captive gray
seals (halichoerus grypus).
Boily, Patrice.
Department of Zoology, University of Guelph, Guelph, Ontario,
Canada, N1G 2W1
APStracts 2:0326R, 1995.
Body mass, resting metabolic rates (RMRs) and serum thyroid hormones
concentrations of six captive gray seals (Halichoerus grypus) were
measured at regular intervals before, during and after the annual
molt. Changes in body mass suggested that the animals had increased
energy expenditures during the last stage of the molt. These were
associated with significantly elevated RMRs during the molt, the
increase being more pronounced in juveniles (up to 53%) than in
adults (up to 17%). The increase in RMR probably reflects the cost of
generating a new pelt or to sustain a high skin temperature. Serum
total and free thyroxine concentrations were elevated for all animals
during the molt, but only juveniles had elevated serum
triiodothyronine concentration. The increase in thyroid hormones
occurred only during the last stage of the molt, suggesting that the
role of thyroid hormones during the molt may be to sustain rapid hair
growth in the last stage of molt or to maintain elevated heat
production, rather than to initiate hair growth.
Received 30 September 1994; accepted in final form 13 November
1995.
APS Manuscript Number R567-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95