THE STOICHIOMETRY OF ANIMAL ENERGETICS

Models for energy uptake and use by animals implicitly specify all mas s transformations, given homeostasis assumptions. This is because mass fluxes can be written as weighted sums of energy fluxes, while the we ight coefficients follow from the conservation law of mass. This paper presents mass transformations on the basis of the dynamic energy budg et model. A theoretical foundation is given for indirect calorimetry, i.e. empirical rules for heat dissipation in terms of oxygen consumpti on, carbon dioxide production and nitrogen outflux. The foundation imp lies a method for obtaining the chemical potentials of structural biom ass and reserves. Conditions on the composition of structural biomass, reserves and nitrogen wastes are derived that ensure a constant respi ration quotient. An explanation is given for the specific dynamic acti on, which turns out to be a simple function of the parameters of the e nergy budget model. A simple model for drinking is presented that take s into account all mass transformations, as implicitly specified by th e energy budget model. (C) 1995 Academic Press Limited