How should mouse pups be fed? - briefly
Neonatal mice need dam colostrum for the initial 24 hours, followed by a species‑specific milk replacer delivered orally every 2–3 hours until weaning at about 21 days.
How should mouse pups be fed? - in detail
Feeding neonatal laboratory mice requires precise timing, appropriate nutrient composition, and strict aseptic technique. Pups receive maternal milk until natural weaning at post‑natal day (PND) 21; supplemental feeding is necessary only when the dam is unavailable, the litter is oversized, or pups exhibit growth retardation.
Timing and volume
- Begin supplemental feeding at PND 3–4, when the oral reflex is functional.
- Provide 10 µL of formula per pup on PND 3, increasing to 30–40 µL by PND 7.
- Offer feeds every 2–3 hours during the light phase; maintain a consistent schedule to avoid hypoglycemia.
Formula composition
- Use a commercially available rodent milk replacer formulated for neonates, containing 20–25 % protein, 40–45 % carbohydrate (lactose or glucose polymers), and 20 % fat (long‑chain triglycerides).
- Supplement with 0.5 % electrolytes (sodium, potassium, calcium, magnesium) and 0.1 % vitamins A, D, E, K.
- Adjust osmolarity to 300–350 mOsm/kg to match natural milk and prevent gastric irritation.
Administration technique
- Warm formula to 37 °C; verify temperature with a calibrated probe.
- Use a sterile, flexible gavage tube (0.5 mm outer diameter) attached to a calibrated syringe.
- Position the pup on a warm pad, hold the head slightly elevated, and insert the tube gently into the esophagus, avoiding the trachea.
- Deliver the measured volume slowly to prevent aspiration; observe for regurgitation and clear the airway if necessary.
Monitoring and adjustment
- Weigh each pup daily; a gain of 1–2 g per day indicates adequate nutrition.
- Inspect for signs of dehydration (skin tenting, sunken eyes) and correct by increasing fluid volume or frequency.
- Record feeding times, volumes, and any adverse events in a laboratory log.
Transition to solid food
- Introduce a softened chow mixture (powdered rodent diet mixed with water at 1:1 ratio) at PND 14.
- Offer the mixture in a shallow dish; allow pups to explore and ingest voluntarily.
- Gradually reduce supplemental milk by 10 % each day from PND 16 onward, completing weaning by PND 21.
Hygiene and biosecurity
- Disinfect all feeding equipment between pups with 70 % ethanol followed by sterile water rinse.
- Change bedding daily and maintain ambient temperature at 30 °C for the first week, decreasing to 26 °C by PND 14.
- Limit personnel contact to essential procedures; wear gloves and lab coat to reduce contamination risk.
Adhering to these protocols ensures optimal growth, minimizes morbidity, and supports reliable experimental outcomes.