What is the typical size of a mouse colony and how many individuals can it include? - briefly
A conventional laboratory mouse colony contains about 20–100 breeding pairs, which can produce roughly 200–1,000 animals across several generations. The exact count depends on breeding strategy, turnover rate, and space constraints.
What is the typical size of a mouse colony and how many individuals can it include? - in detail
A mouse colony in a research facility typically comprises anywhere from a few dozen individuals to several thousand, depending on the purpose of the colony, the strain used, and the available housing infrastructure.
Standard individually ventilated cages (IVCs) are designed for 4–5 mice each. A single rack holds roughly 100 cages, allowing a maximum of 400–500 animals per rack. Many institutions operate multiple racks within a room, so a moderate‑size colony often contains 1,000–2,000 mice. Large breeding programs can exceed 5,000 individuals when several rooms are dedicated to the same strain.
Breeding dynamics determine how quickly a colony expands. A typical breeding pair produces 6–8 pups per litter, with 3–4 litters per year, yielding 20–30 offspring annually per pair. Consequently, a colony of 100 breeding pairs can generate 2,000–3,000 new mice each year, requiring culling, sub‑colonizing, or redistribution to maintain a manageable size.
Regulatory guidelines set limits on the number of animals per cage and per room to ensure adequate space, ventilation, and welfare. For example, the Guide for the Care and Use of Laboratory Animals recommends a minimum of 75 in² floor space per mouse, which translates to the standard 4–5 mouse capacity per IVC. Facility managers calculate total capacity by multiplying the number of usable cages by the per‑cage limit and then applying a safety margin (commonly 10 %) to accommodate equipment, cleaning aisles, and quarantine areas.
In practice, a typical colony used for experimental studies may consist of 200–500 mice, providing sufficient statistical power while remaining within the logistical constraints of most vivaria. Breeding colonies maintained for strain preservation often operate at a larger scale, ranging from 1,000 to 3,000 animals, with additional space allocated for backup lines and genetic quality control.