The respiratory quotient in indirect calorimetric measurements.

Respiratory quotients (RQ) smaller than 0.70 must be associated with partial oxidation of the biological substrates and storage of oxygen in the carcass or the excreta. An equation for the calculation of the amount of oxygen stored in relation to the RQ is described. The fluxes of N, C, H and O in the carcass of the fasting fowl were negative and compatible with the complete oxidation of the biological substrates. The amounts of these elements in the excreta corresponded with the nitrogenous excretion products, carbohydrates and minerals. No substantial oxygen storage could be demonstrated. The very low RQ values reported in the past would require a magnitude of oxygen storage which is incompatible with life.