What should a laboratory rat be fed? - briefly
A laboratory rat should receive a nutritionally complete, standardized rodent chow containing calibrated levels of protein, fat, carbohydrates, vitamins, and minerals, with water available at all times. Occasionally, a small amount of fresh fruits, vegetables, or sterile grain can be added to enhance enrichment.
What should a laboratory rat be fed? - in detail
Laboratory rats require a nutritionally balanced diet that supports rapid growth, high reproductive rates, and the physiological demands of experimental protocols. The feed must be sterile, consistent in composition, and free of contaminants that could influence study outcomes.
A standard rodent chow formulation includes the following macronutrient and micronutrient specifications:
- Protein: 18–20 % of total calories, derived from soy, casein, or a blend of plant and animal sources. Essential amino acids must meet the National Research Council (NRC) recommendations for rodents.
- Fat: 4–5 % of calories, supplied primarily as soybean oil or corn oil to provide essential fatty acids (linoleic and α‑linolenic acids).
- Carbohydrate: 50–55 % of calories, predominantly from cornstarch, providing a steady energy source.
- Fiber: 5–6 % crude fiber, sourced from cellulose or beet pulp, to maintain gastrointestinal motility and microbiome stability.
- Vitamins: Adequate levels of vitamins A, D3, E, K, B‑complex, and C, formulated to prevent deficiencies that could affect immune response or metabolism.
- Minerals: Calcium, phosphorus, magnesium, potassium, sodium, chloride, and trace elements (iron, zinc, copper, manganese, selenium, iodine) in ratios that sustain bone health, enzymatic function, and electrolyte balance.
- Water: Unlimited access to autoclaved or filtered water, optionally supplemented with electrolytes or glucose for specific experimental conditions.
Additional considerations for specialized protocols:
- High‑energy diets for breeding colonies or studies involving weight gain; increase fat content to 10 % and protein to 22 %.
- Low‑protein or restricted diets for renal or metabolic research; reduce protein to 8–10 % and adjust phosphorus accordingly.
- Purified diets (e.g., AIN‑93G or AIN‑93M) when ingredient variability must be minimized; ingredients are chemically defined, eliminating batch‑to‑batch differences.
- Palatability enhancers such as sucrose or flavored gels for animals recovering from surgery or experiencing reduced appetite; must be accounted for in caloric calculations.
- Allergen‑free formulations for studies on immune responses; eliminate common protein sources like soy or casein and replace with defined amino acid mixtures.
Feeding schedules should align with the circadian rhythm of rats, providing food ad libitum unless restriction is part of the experimental design. Monitoring body weight weekly, recording food intake, and checking for signs of malnutrition (e.g., coat deterioration, reduced activity) are essential quality‑control practices.
Sterilization of feed can be achieved through gamma irradiation (25 kGy) or autoclaving (121 °C, 15 psi, 30 min). Both methods preserve nutrient integrity while eliminating bacterial, fungal, and viral contaminants.
In summary, a laboratory rat’s diet must be formulated to meet precise nutritional benchmarks, remain sterile, and be adaptable to the specific demands of each research protocol. Consistent documentation of feed composition, storage conditions, and consumption metrics safeguards experimental reproducibility and animal welfare.