On the calculation of heat production from open-circuit calorimetric measurements

1. The equation used for calculating heat production of ruminant animals is expressed in a new form, convenient for application to open-circuit calorimetry. 2. It is shown that in open-circuit calorimetry the possible error involved in making the assumption that respiratory quotient is equal to unity is small compared with the possible error involved in neglecting methane production. 3. In open-circuit calorimetry heat production can be predicted with accuracy to within ± 2% solely from the measurement of oxygen concentration and ventilation rate.