Document Detail

Test of a digestion optimization model: effects of costs of feeding on digestive parameters.
MedLine Citation:
PMID:  9548649     Owner:  NLM     Status:  MEDLINE    
We tested predictions of a chemical reactor model of digestion by manipulating the short-term costs of feeding and then measuring the effect on digestive parameters. We compared residence time of digesta and extraction efficiency of glucose in cold-acclimated waxwings (Bombycilla cedrorum) feeding ad lib. and in birds whose costs of feeding were increased through the addition of intervals of time when they received no food. Such a feeding schedule simulated the ecological situation in which a frugivorous bird like a waxwing encounters food in patches and experiences nonfeeding periods as it searches for new preferred food patches. None of the results were consistent with the predictions of the optimal digestion model: extraction efficiency was independent of costs of feeding, and residence times did not increase as costs of feeding increased. This empirical evidence on the passage of digesta in waxwings suggests that movement of digesta in the guts of birds is much more complex than movement of material in an ideal chemical reactor. Tests of the optimal digestion model have involved manipulating food quality or the costs of feeding, and the conclusions are similar: compensatory modulation of retention time or digesta mixing and not rate of hydrolysis and absorption seem most important in maintaining the remarkably constant digestive efficiency.
S R McWilliams; W H Karasov
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Physiological zoology     Volume:  71     ISSN:  0031-935X     ISO Abbreviation:  Physiol. Zool.     Publication Date:    1998 Mar-Apr
Date Detail:
Created Date:  1998-05-29     Completed Date:  1998-05-29     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0401142     Medline TA:  Physiol Zool     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  168-78     Citation Subset:  IM    
Department of Wildlife Ecology, University of Wisconsin-Madison, 53706, USA.
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MeSH Terms
Birds / physiology*
Digestion / physiology*
Energy Metabolism*
Feeding Behavior / physiology*
Models, Biological
Plants, Edible

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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