What do newborn mice eat? - briefly
Newborn mice are obligate mammals; they feed exclusively on their dam’s milk, beginning with colostrum and continuing with regular milk until weaning at about three weeks of age. No other food sources are consumed during this period.
What do newborn mice eat? - in detail
Newborn laboratory mice obtain all nutrients from the dam’s lactation. The first 24 hours after birth involve continuous suckling; litters typically nurse every 1–2 hours, receiving 5–10 µl of milk per bout. Milk is rich in casein and whey proteins (≈ 30 % of total solids), providing essential amino acids for rapid tissue growth. Lipids constitute about 45 % of the caloric content, primarily long‑chain triglycerides that supply energy and support brain development. Lactose supplies carbohydrate calories and promotes intestinal flora balance, while trace minerals and vitamins are present in concentrations sufficient for the first week of life. Immunoglobulin G and other antimicrobial factors transferred through the colostrum protect against infection until the pup’s own immune system matures.
The composition of maternal milk changes with the lactation stage. Early milk (colostrum) contains higher immunoglobulin levels and lower fat content; transitional milk (days 3–7) increases lipid concentration, and mature milk (post‑day 10) stabilizes protein‑to‑fat ratios. These shifts correspond to the pups’ escalating energy demands as they double body weight each week.
When the dam is unavailable, artificial milk replacers are formulated to mimic natural milk. Standard formulas provide approximately 20 kcal ml⁻¹, with protein (≈ 10 % w/v), fat (≈ 12 % w/v), and lactose (≈ 6 % w/v). Feeding is performed with calibrated pipettes or specialized nursing devices, delivering 10–15 µl per feeding at 1‑hour intervals during the first week, then gradually extending intervals as the pups approach weaning.
Weaning occurs between post‑natal day 21 and 28. During this period, solid food intake rises while milk consumption declines. By day 25, pups typically consume 0.5 g of standard rodent chow per day, supplemented by residual milk. Successful transition requires gradual exposure to dry food, often introduced as a fine powder mixed with a small amount of milk replacer to facilitate acceptance.
Maternal factors influencing neonatal nutrition include parity, health status, and diet. Dams on a protein‑adequate diet (≥ 18 % crude protein) produce milk with higher casein content, supporting faster growth rates. Stress or illness can reduce milk output, leading to increased mortality unless supplemental feeding is provided.
In summary, the diet of neonatal mice consists exclusively of dam’s milk, characterized by high protein, lipid, and lactose concentrations, with dynamic compositional changes that match developmental needs. Artificial formulas replicate these nutrients for orphaned pups, while weaning introduces solid chow in a staged manner to ensure continued growth and health.