Title
Seasonal Differences in Biochemical Adaptation to Fasting in Juvenile and Subadult Steller Sea Lions (Eumetopias jubatus)
Abbreviated Journal Title
Physiol. Biochem. Zool.
Keywords
NORTHERN ELEPHANT SEAL; POSTWEANING FAST; BLOOD-CHEMISTRY; MIROUNGA-ANGUSTIROSTRIS; ATTENDANCE PATTERNS; PROTEIN-UTILIZATION; EMPEROR PENGUINS; BODY-COMPOSITION; FUR SEALS; PUPS; Physiology; Zoology
Abstract
Nine Steller sea lions (Eumetopias jubatus) aged 1.75-6 yr were experimentally fasted for 7-14 d during the breeding and non-breeding seasons to identify changes in plasma metabolites that are indicative of fasting and to determine whether the ability of sea lions to fast varies seasonally or with age. Although some animals approached the limit of their protein-sparing ability by the end of our fasting experiments, there was no sign of irreversible starvation biochemistry. Plasma blood urea nitrogen (BUN) concentrations decreased in all animals within the first week of fasting, reflecting a shift to a fasting-adapted state; however, significant increases in plasma BUN concentration at the end of the nonbreeding season fasts suggest that subadult Steller sea lions were not able to maintain a protein-sparing metabolism for a full 14 d during the nonbreeding season. In contrast, juveniles were able to enter protein sparing sooner during the nonbreeding season when they had slightly higher initial percent total body lipid stores than during the breeding season. Subadult and juvenile sea lions had low circulating ketone body concentrations compared with young sea lion pups, suggesting an age-related difference in how body reserves are utilized during fasting or how the resulting metabolites are circulated and catabolized. Our data suggest that metabolite concentrations from a single blood sample cannot be used to accurately predict the duration of fast; however, threshold metabolite concentrations may still be useful for assessing whether periods of fasting in the wild are unusually long compared with those normally experienced.
Journal Title
Physiological and Biochemical Zoology
Volume
82
Issue/Number
3
Publication Date
1-1-2009
Document Type
Article
DOI Link
Language
English
First Page
236
Last Page
247
WOS Identifier
ISSN
1522-2152
Recommended Citation
"Seasonal Differences in Biochemical Adaptation to Fasting in Juvenile and Subadult Steller Sea Lions (Eumetopias jubatus)" (2009). Faculty Bibliography 2000s. 2043.
https://stars.library.ucf.edu/facultybib2000/2043