How much does a rat eat? - briefly
A typical adult rat consumes roughly 5–10 % of its body weight daily, about 1–2 g of solid food, plus water. Intake varies with age, strain, and diet composition.
How much does a rat eat? - in detail
A typical adult laboratory rat (≈250 g body mass) consumes 15–20 g of standard pelleted chow per day, which corresponds to 6–8 % of its weight. Juvenile rats grow faster and may ingest 5–7 g daily, while pregnant or lactating females increase intake by 30–50 % relative to non‑reproductive adults. Wild brown rats obtain food opportunistically; studies report daily grain or carbohydrate intake ranging from 10 to 25 g, supplemented by insects and refuse, resulting in a similar proportion of body mass but with greater variability due to seasonal availability.
Pet rats are usually fed a combination of laboratory‑grade pellets, fresh vegetables, and occasional protein treats. A balanced daily ration for a 300 g pet rat includes:
- 20–25 g of high‑quality pellets (≈7 % of body weight)
- 10–15 g of fresh vegetables (e.g., carrots, broccoli, leafy greens)
- 2–3 g of protein sources (hard‑boiled egg, cooked chicken)
- Unlimited access to clean water
Factors that modify consumption:
- Age – newborns receive maternal milk; weaning rats shift to solid food and increase intake sharply.
- Metabolic rate – higher ambient temperatures reduce food requirements; colder environments raise them.
- Activity level – rats engaged in extensive exercise or enrichment consume more calories.
- Health status – illness or dental problems can cause a noticeable drop in intake.
When calculating nutritional needs, use the guideline of 6–8 % of body weight in dry matter per day. For a 350 g rat, the target dry‑food amount is 21–28 g. Adjust upward for breeding females or colder housing, and downward for sedentary or older animals. Monitoring daily leftovers provides a practical method to verify that the animal meets its energy requirements without excess.