Changes in stable nitrogen isotope (δ 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 δ 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, 1995-96. We correlated serum IGF-1 concentrations of the percent of total body fat determined by BIA and their serum and erythrocyte δ 15N levels to lean body mass determined by BIA. Neither δ 15N nor IGF-1 had a significant relation with body composition. Ideas and problems for further research are presented and discussed.
- Volume 13
- Issue
- Pages 285-291
- Publication Date 1 January 2002
- DOI
- File Size 326.17 KB
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