How much does a rat weigh per month? - briefly
A newborn rat typically weighs 5–7 g, and by the end of its first month its mass increases to roughly 150–200 g, varying with strain and sex. Adult females usually settle around 180–250 g, while males reach 250–300 g.
How much does a rat weigh per month? - in detail
Rats increase body mass rapidly during the first few months of life. A newborn typically weighs 5–7 g. By the end of the first month the average mass reaches 40–60 g, reflecting a growth rate of roughly 35–55 g per week. In the second month the weight climbs to 80–120 g, with weekly gains of 10–15 g. The third month brings the animal to 130–200 g, after which growth slows considerably. From the fourth to the sixth month the increase is modest, usually 10–20 g per month, and most individuals attain adult size between 250 g and 500 g, depending on strain, sex, and nutrition.
Key factors influencing the monthly weight trajectory include:
- Genetic line – laboratory strains (e.g., Sprague‑Dawley) tend to be larger than wild‑type or dwarf varieties.
- Sex – males generally exceed females by 10–20 % in adult weight.
- Diet quality – high‑protein, balanced feed accelerates growth; nutrient deficiencies delay it.
- Health status – illness or parasitic load can cause weight loss or stunted development.
- Housing conditions – temperature, stress, and enrichment affect metabolic rate and muscle development.
Monitoring involves weighing the animal at consistent intervals, ideally weekly during the first three months and monthly thereafter. A stable upward trend indicates proper nutrition and health, while plateaus or declines warrant veterinary assessment. Maintaining a diet of 15–20 % protein, adequate calories, and clean water supports the expected monthly weight gains outlined above.