Strain-specific effects of cage enrichment in male laboratory mice (Mus musculus) (1999)

Nevison, C. M., Hurst, J. L., Barnard, C. J.

Abstract

The relationship between aggression, testosterone and 'enrichment' [clear Perspex tunnel and a small handful of shredded tissue] suggest that increasing complexity in laboratory cages may increase a naturally selected territorial response in some strains. ... Enrichment, as used in this study, could be interpreted as improving the welfare of male mice, as it apparently encouraged aspects of a naturally selected response (territoriality) and increased interest in the environment within and external to the cage. However, these responses were encouraged within a highly artificial environment, and may not be appropriate.