What is a metabolism cage used for?

• A. Measure food and water intake
• B. Measure feces and urine output
• C. Measure oxygen and carbon dioxide
• D. All of the above

Answer: (D)

Metabolism cages are designed to monitor an animal’s energy balance by capturing multiple data streams in a controlled housing environment. They provide a precise way to measure what the animal eats and drinks, as well as what it excretes, by using a food hopper and a water bottle with accurate intake measurements and a dedicated collection system for feces and urine. In more advanced setups, these cages can also be connected to gas analyzers to track oxygen consumption and carbon dioxide production, enabling indirect calorimetry to assess metabolic rate. Because they can combine intake, waste output, and respiratory gas measurements, they cover all these functions, making “All of the above” the best description.