Long-term fasting and re-feeding in penguins

Spontaneous fasting during reproduction (sometimes with a full stomach) and moult is a major characteristic of the annual cycle of penguins. Long-term fasting (up to four months in male emperor penguins) is anticipated by the accumulation of fat (incubation fast) and of fat and protein (moult fast)....

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Bibliographic Details
Published in:Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2001-03, Vol.128 (3), p.643-653
Main Authors: Groscolas, René, Robin, Jean-Patrice
Format: Article
Language:English
Subjects:
Animals
Birds - physiology
Egg abandon
Fasting
Fat stores
Feeding Behavior
Incubation
Marine
Penguins
Re-feeding signal
Spheniscidae
Starvation
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Summary:Spontaneous fasting during reproduction (sometimes with a full stomach) and moult is a major characteristic of the annual cycle of penguins. Long-term fasting (up to four months in male emperor penguins) is anticipated by the accumulation of fat (incubation fast) and of fat and protein (moult fast). During most of the incubation fast, birds rely almost entirely on lipids as an energy source, body proteins being spared. However, below a critical (but non-total) fat store depletion, marked behavioural, metabolic, and endocrine changes occur. Spontaneous locomotor activity increases and the egg is transitorily left unincubated for increasingly long periods, until its definitive abandon and the bird departs to re-feed at sea. These changes are thought to be activated by an endogenous re-feeding signal triggered before lethal energy depletion. An increase in body protein catabolism in the face of a reduction in lipid availability and utilisation, and an increase in circulating corticosterone vs. a decrease in plasma prolactin, are likely to be major metabolic and hormonal components of this signal. The survival and rapid restoration of energy stores in birds having departed to re-feed at a stage of near total lipid depletion demonstrates the effectiveness of the re-feeding signal. Penguins, and possibly other seabirds, are therefore appropriate animal models for understanding the long-term interactions between body energy reserves and fasting, breeding and feeding physiology and behaviour.
ISSN:1095-6433
1531-4332
DOI:10.1016/S1095-6433(00)00341-X