How much does a two-month-old rat weigh? - briefly
A typical eight‑week‑old laboratory rat weighs between 150 g and 200 g, depending on strain and sex. This range reflects normal growth for a healthy juvenile rodent.
How much does a two-month-old rat weigh? - in detail
A rat that is eight weeks old typically weighs between 120 g and 200 g. The exact mass depends on several variables:
- Strain: Laboratory strains such as Sprague‑Dawley or Wistar often fall near the upper end of the range, while smaller wild‑type or dwarf strains can be closer to 120 g.
- Sex: Males usually exceed females by 10–20 g at this age.
- Nutrition: Standard rodent chow yields growth rates that keep weight within the cited interval; high‑fat diets can push individuals above 200 g.
- Housing conditions: Ambient temperature, cage density, and enrichment affect metabolic rate and, consequently, body mass.
Weight measurements are obtained with a calibrated analytical balance, recording the animal’s mass to the nearest 0.1 g after a brief acclimation period. Repeated readings over consecutive days provide a reliable growth curve, allowing researchers to detect deviations caused by disease, genetic manipulation, or experimental treatment.
Reference data from peer‑reviewed studies report mean weights of 150 g for male Sprague‑Dawley rats and 135 g for females at eight weeks, with standard deviations of approximately 10 g. These figures serve as benchmarks for assessing normal development and for calculating dosage in pharmacological experiments.