How many calories are in a mouse? - briefly
A typical adult house mouse weighing about 25 g contains roughly 30 kcal (≈125 kJ) of metabolic energy. The exact value depends on the mouse’s size and body composition but generally falls between 20 and 35 kcal.
How many calories are in a mouse? - in detail
A typical adult house mouse weighs between 15 g and 25 g. Energy density of lean mammalian tissue averages about 1.4 kcal per gram, derived from protein (4 kcal g⁻¹) and a modest fat fraction (9 kcal g⁻¹). Assuming a 20 g specimen with 20 % protein and 5 % lipid, the caloric contribution is:
- Protein: 4 g × 4 kcal g⁻¹ = 16 kcal
- Fat: 1 g × 9 kcal g⁻¹ = 9 kcal
Total ≈ 25 kcal per mouse. Variation in body composition, age, and species shifts this value by ±5 kcal.
Factors influencing the energy content:
- Weight range – larger individuals contain proportionally more tissue.
- Fat proportion – higher adiposity raises calories by ~9 kcal per gram of fat.
- Hydration level – water does not contribute calories but dilutes tissue mass.
- Species – laboratory mice (Mus musculus) differ from larger field mice (e.g., Apodemus sylvaticus) in size and fat stores.
- Dietary history – animals fed high‑energy diets accumulate more fat, increasing caloric value.
For comparative purposes, a single mouse provides roughly the same energy as a small piece of lean chicken breast (≈ 30 g) or about one‑tenth of a typical human snack bar. The estimate remains approximate; precise measurement requires bomb calorimetry of the specific specimen.