How many grams of food should be given to a rat? - briefly
An adult laboratory rat typically receives 5–10 grams of standard pelleted chow per day, with exact amounts adjusted for body weight, age, and activity level. Nutrition guidelines suggest monitoring body condition and modifying the ration to maintain stable weight.
How many grams of food should be given to a rat? - in detail
Determining the proper daily food quantity for a laboratory rat requires consideration of several physiological and experimental variables. The calculation begins with the animal’s body mass, which typically ranges from 150 g for a juvenile to 300 g for an adult. Energy requirements for a standard laboratory rat are approximately 15–20 kcal per 100 g of body weight per day. Assuming a balanced pelleted diet containing about 3.5 kcal g⁻¹, the following formula provides a baseline estimate:
Daily feed (g) = (Body weight × Energy need) ÷ Dietary energy density
Applying the average values:
- 200 g rat × 0.17 kcal g⁻¹ = 34 kcal needed per day
- 34 kcal ÷ 3.5 kcal g⁻¹ ≈ 9.7 g of feed
Guidelines from the National Research Council and common laboratory practice suggest feeding 10–12 g per day for a 200 g adult, with adjustments for the following factors:
- Age: Juveniles require 8–10 g; seniors may need 12–14 g.
- Strain: Metabolic rates differ; for high‑metabolism strains increase by 10 %.
- Sex: Males generally consume 5 % more than females of equal weight.
- Activity level: Enriched environments or exercise protocols add 1–2 g.
- Diet composition: High‑fat or high‑protein formulations alter caloric density; recalculate using the specific kcal g⁻¹ value.
A practical feeding schedule:
- Weigh each animal at the start of the week.
- Calculate the individual requirement using the formula above.
- Provide the measured amount in a single daily portion to ensure consistent intake.
- Monitor body weight weekly; adjust feed by ±5 % if weight deviates more than 5 % from target.
Consistent measurement with an analytical balance and recording in a logbook supports reproducibility and animal welfare. «Accurate dosing of nutrition» reduces variability in experimental outcomes and aligns with ethical standards for laboratory animal care.