Oxygen consumption and carbon dioxide production is measured using indirect calorimetry. The Columbus Instruments Oxymax Equal Flow System is an indirect open circuit calorimeter designed to simultaneously measure metabolic performance of multiple subjects that have similar ventilation needs. uses an open circuit calorimetry technique. This system allows sixteen animal cages to be simultaneously monitored. Variables provided by this measurement include VO2, VCO2, RQ, and HEAT.
A food reservoir is placed on a sensitive balance and introduced to the animal through specially designed cages that prevent defecating/urinating into or spillage of food. Data is generated at intervals of 1 minute to 9999 hours and 59 minutes. Meal patterns can be analyzed with this system by checking the frequency and duration of each meal. Sixteen animal cages can be simultaneously monitored.