How many mice can give birth and how many times? - briefly
A female mouse becomes fertile at about six weeks of age and can have 5–10 litters per year, each litter usually containing 5–8 pups. Over a typical reproductive lifespan of roughly one year, this yields 30–80 offspring per mouse.
How many mice can give birth and how many times? - in detail
Mice reach sexual maturity at 5–8 weeks of age. The estrous cycle lasts 4–5 days, and a female can become fertile again within 24 hours after giving birth, a phenomenon known as postpartum estrus.
A typical litter contains 5–8 pups, although extremes of 3 and 13 have been recorded in various strains. The average litter size for common laboratory strains (e.g., C57BL/6, BALB/c) is 6.5 ± 1.2 pups.
Gestation lasts 19–21 days. After parturition, pups are weaned at 21 days, and the dam can be re‑mated immediately. Under optimal conditions a mouse can produce:
- 5–7 litters per year in a conventional housing environment.
- Up to 10 litters per year when breeding cycles are tightly managed and the interval between weaning and the next mating is minimized to 1 day.
Consequently, a single female can generate approximately 30–70 offspring over a reproductive lifespan of 12–18 months, assuming consistent health and nutrition.
Factors that modify these figures include:
- Genetic strain: some lines (e.g., Swiss outbred) exhibit larger litters and higher frequency than inbred strains.
- Diet: protein‑rich or calorie‑dense diets increase litter size and reduce inter‑litter interval.
- Environmental conditions: temperature, lighting, and cage density affect estrous regularity and pup survival.
- Health status: disease or stress suppress ovulation and reduce litter viability.
In summary, a healthy mouse can produce multiple litters annually, each containing several pups, leading to a total reproductive output that can exceed fifty individuals per female during a typical lifespan.