Journal Publications
Gau, R.J. and R. Case. 2002.
Evaluating nutritional condition of grizzly bears via 15N
signatures and insulin-like growth factor-I. Ursus 13:285-291.
Abstract
Changes in stable nitrogen isotope (*15N)
values in animal tissues may be an indicator of lean-tissue losses and thus
reflect changes in nutritional condition. Adequate nutrient intake may be
reflected by insulin-like growth factor (IGF-1) synthesis and secretion into
the systemic circulation and thus also reflect changes in nutritional
condition. However, the use of
*15N
and IGF-1 to estimate the nutritional condition of bears has yet to be
validated with actual body compositions. We used bioelectrical impedance
analysis (BIA) to estimate the body composition of a free-ranging population
of grizzly bears (Ursus arctos) from the central Arctic of the
Northwest Territories, Canada. We correlated serum IGF-1 concentrations to
the percentage of total body fat determined by BIA, and their serum and
erythrocyte
*15N levels
to lean body mass determined by BIA. Neither
*15N
nor IGF-1 had a significant relation with body composition. Ideas and
problems for further research are presented and discussed. | 
