Energy expenditure, intake and balance in free-living animals: a
novel approach based on the doubly labelled water method.
Kam, Michael, and A. Allan Degen.
Desert Animal Adaptations and Husbandry, Jacob Blaustein Institute
for Desert Research, Ben-Gurion University of the Negev, Beer Sheva,
84105 Israel
APStracts 3:0371R, 1996.
We provide a theoretical and practical model for the calculation of
energy balance of free-living animals using the doubly labelled water
method. Energy expenditure, metabolizable energy intake and body
energy balance (energy retention, negative or positive) of animals
are estimated using CO2 production, water influx and dietary habits.
This model accounts for CO2 produced from the 1) oxidation of dietary
substrates; 2) catabolism of body tissue; and 3) deposition of body
energy. We examined the model using data from studies on five
homeotherms reported in the literature. The ratios between daily
energy expenditure using our model and that presented in the reports
ranged between 0.76 and 1.18. Metabolizable energy intakes were as
low as 43% of energy expenditure in negative energy balanced
hummingbirds and as high as 245% of energy expenditure in positive
energy balanced koala bears. This model is the first that allows
theoretical calculation of all energy budget components, including
energy retention, in free-living animals using DLW.
Received 2 April 1996; accepted in final form 8 October 1996.
APS Manuscript Number R191-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996