How many offspring does a white rat have? - briefly
A typical litter of a white laboratory rat consists of six to twelve offspring, averaging about eight to ten pups.
How many offspring does a white rat have? - in detail
White rats (Rattus norvegicus) usually produce between six and twelve pups per litter. The most common litter size is eight, but records show litters as small as four and as large as fourteen under optimal conditions.
Key factors that modify this range include:
- Maternal age: Young females (first estrus) often have smaller litters; mature females reach peak output around 4‑6 months.
- Nutrition: Adequate protein and caloric intake raise pup numbers; deficiencies can reduce litter size.
- Genetics: Strains selected for laboratory use (e.g., Sprague‑Dawley, Wistar) tend toward the higher end of the spectrum.
- Environmental conditions: Stable temperature (20‑24 °C) and low stress improve reproductive performance.
- Parity: Second and third pregnancies generally yield larger litters than the first.
The gestation period for a white rat lasts 21‑23 days. After birth, females can become fertile again within 48‑72 hours, allowing for up to five litters per year in a well‑managed colony. Consequently, an individual can produce roughly 30‑60 offspring annually, depending on the variables listed above.