Share thisSo, is more always better?
After review of many animal facilities, there appears to be no norm for the number of racks of mouse boxes in animal holding rooms for a standard vivarium. A range is found anywhere from 3 – 20 racks per room, each holding from 98 – 160 cages per rack. Although some rooms may have <3 or >20 racks, most commonly the number of racks will be found within these limits. One might ask if there is an optimum for the number of racks per animal holding room (AHR) and, furthermore, if that norm is the same or different from an animal care technician’s perspective, researchers and their staff, veterinary and health surveillance technicians, consideration of “green” utility efficiencies, or from any number of other criteria. Interestingly, the number of cages indexed to usable square feet within such a range of racks per room varies within a relatively narrow range, that being between 2.0 – 3.0 cages per AHR net square foot. While this value is impacted by the number of cages per rack, it remains notable that the values have a small range. Figure 1 illustrates two different room configurations with widely different cage capacities ranging from fewer than 1000 to greater than 5000 cages per room; yet, the room density, i.e., cages/usable square foot, ranges only from 2.2 – 2.8 cages/net square foot.
