Scientific apparatus for measurement, monitoring, and analysis of metabolic activity in animals, comprised of gas analyzers, gas flow rate monitors, gas flow generators, gas manifolds, and channel switchers for animal mass measurement, food and water mass measurement, and controllers for monitors and management of gas concentrations, gas flow, air flow, temperature management, relative humidity management, and access to food and water, namely, measuring use of air, food and water intake and energy expenditure; scientific animal monitoring apparatus, namely, monitors for collecting and analyzing behavioral data, namely, activity, exercise, position and movement within animal chambers; laboratory equipment, namely, full body or partial body animal hoods, masks, cages, and chambers, and racks to support animal cages, all for use in scientific analysis of animals; computer software for measuring, monitoring, and analyzing metabolic activity in animals, and data acquisition interface hardware and instruction manuals packaged therewith, sold as a unit