Measurement of the respiratory metabolism of the fowl

1. The occurrence of low respiratory quotients (RQ) in fowls and the reliability of oxygen consumption, carbon dioxide output and heat production data in indirect calorimetry were studied.

2. The RQ, data from the gravimetric and the combined gravimetric‐volumetric systems were essentially the same, while differences in O₂ and CO₂ between the systems were primarily due to variations in environmental temperature.

3. Fasting RQ, was never less than 0.70 in these systems.

4. In the volumetric system the O₂, CO₂ and RQ, data from the diaferometer were significantly different from the infra‐red and paramagnetic analyses.

5. The CO₂ values from the diaferometer were correct, but the O₂ values were too low. In the specific analysers the reverse was seen, the paramagnetically‐determined O₂ values being correct and the CO₂ values from infra‐red analysis being too low.

6. Thus the fasting RQ values from the diaferometer were too high (0.762) and from the specific analysers too low (0.683).