Effect of a low-fat diet on body composition and blubber fatty acids of captive juvenile harp seals (Phoca groenlandica)
Date
2000-01
Authors
Kirsch, PE
Iverson, Sara J.
Bowen, WD
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Abstract
We investigated the effects of a change from a high-fat diet to a low-fat diet of differing
fatty acid (FA) composition on the body composition and blubber FA of five captive juvenile harp
seals. Seals that had been maintained for 1 yr on a diet of Atlantic herring (greater than or equal
to 9% fat) were switched to a diet of Atlantic pollock (1.7% fat) for 30 d. On days 0, 14, and 30,
mass and body composition (using isotope dilution) were measured, and blubber biopsies (5 cm x 6 mm)
were taken for FA analysis. Fat accounted for 38%-49% of body mass at the start of the experiment.
When switched to the pollock diet, and despite food intakes averaging 6.5 kg/d (32.3 MJ/d), body
fat: declined by an average of 6.4 kg or by 32% over the 30-d experiment. In contrast, body protein
increased in direct relation to protein intake (r(2) = 0.836, P = 0.030). Despite substantial loss
of body fat, blubber FA signature changed significantly to reflect the changes in dietary intake of
FA, and the deposition of FA was quantifiably predictable. Our results suggest that young growing
phocids are unable to maintain body fat stores on low-fat diets even when protein intakes are high.
This may have significant implications for juvenile pinniped survival in the wild. In addition,
turnover and deposition of dietary FA in blubber takes place in nonfattening seals.
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Citation
Kirsch, PE, SJ Iverson, and WD Bowen. 2000. "Effect of a low-fat diet on body composition and blubber fatty acids of captive juvenile harp
seals (Phoca groenlandica)." Physiological and Biochemical Zoology 73(1): 45-59. Copyright © 2000 The University of Chicago Press.