How much food should a rat eat? - briefly
A typical adult rat eats about 15–20 g of standard laboratory chow each day, which equals roughly 5–7 % of its body weight. Intake varies with age, strain, activity level, and diet composition.
How much food should a rat eat? - in detail
Rats require a diet that supplies roughly 15–20 kcal per 100 g of body weight each day. An adult laboratory or pet rat weighing 250–300 g therefore needs about 38–60 kcal daily. This energy translates to approximately 20–30 g of standard rodent chow, which typically contains 3.5–4.0 kcal per gram.
Key variables influencing intake:
- Age: Juvenile rats (4–6 weeks) grow rapidly and may consume 1.5 times the amount given to adults of similar weight.
- Sex: Males often have slightly higher caloric demands than females of equal mass.
- Activity level: Rats housed with enrichment, running wheels, or frequent handling burn more calories and will increase consumption accordingly.
- Health status: Illness, stress, or pregnancy can reduce appetite, while recovery periods may require supplemental feeding.
Feeding schedule should provide constant access to fresh pellets, supplemented with occasional treats such as fresh vegetables (e.g., carrots, broccoli) or small pieces of fruit. Treats must not exceed 10 % of total caloric intake to prevent obesity.
Practical feeding guidelines:
- Offer a measured portion of 20 g of high‑quality pellet diet per day for a 250 g adult rat.
- Adjust upward by 5 g for active individuals or those weighing over 300 g.
- Reduce by 2–3 g for sedentary or older rats.
- Provide fresh water at all times; a typical adult consumes 30–50 ml daily.
- Replace uneaten food each morning to maintain hygiene and prevent spoilage.
Monitoring body weight weekly ensures the diet remains appropriate. A stable weight within the species‑specific range (250–300 g for adults) indicates adequate nutrition. Sudden weight loss or gain signals the need to reevaluate portion size, diet composition, or health status.