Population density and growth rate in laboratory mice

Home Office guidelines recommend an area of 60 cm2 per mouse for growing mice up to 30 g. However, the overall growth rate, and final adrenal weight of weanling BALB/c and MF1 strain mice was not affected by being housed at a density of down to 27 cm2 per mouse, though there was some evidence of strain differences in ability to tolerate such dense housing. The presence of cage accessories had no effect on growth rate of BALB/c and female mice, but reduced growth of MF1 and male mice, though the effect was small. It is concluded that present Home Office guidelines make a generous provision for the space requirements of growing laboratory mice, and that the use of cage accessories of varying design may be worth exploring in more detail.