Clustered environmental enrichments induce more aggression and stereotypic behaviour than do dispersed enrichments in female mice

Female C57BL/6 mice show consistent individual differences in spontaneous interaction with environmental enrichment that are predicted by neophobia

“…A few subjects appeared to actively prefer the enriched environment (two pairs ate from the enriched cages more than expected by chance), while others found it relatively aversive, many pairs eating from the enriched cage less than would be expected by chance. This relatively low overall preference was at odds with a recent experiment from our lab [46] using mice of the same age, sex and source, in which all mice housed in two interconnected standard cages, one containing a regularly renewed Kleenex, of enrichment-interaction: over the entire course of the experiment, there was a weekly day-long decrease in enrichment-use, as indexed by relative feed consumption, after each day of cagecleaning (standard and enriched cages) and enrichment rotation (enriched cages only). Furthermore, the aspects of phenotype helping to determine enrichment-use also indicated this too: empirically, the most neophobic subjects-as characterised during both novel object tests and hyponeophagia tests-used the enriched cage least.…”

Aggression in group-housed laboratory mice: why can't we solve the problem?

“…Second, shelter enrichments should not be provided in circumstances in which these are known to increase aggression 19 (which is best assessed on a case-by-case basis in each facility). Note that providing multiple shelters per cage or providing shelters to smaller groups may have beneficial effects on aggression 33 , although this has not been studied in males or in isolation from other factors.…”

Reprint of Female C57BL/6 mice show consistent individual differences in spontaneous interaction with environmental enrichment that are predicted by neophobia

“…A few subjects appeared to actively prefer the enriched environment (two pairs ate from the enriched cages more than expected by chance), while others found it relatively aversive, many pairs eating from the enriched cage less than would be expected by chance. This relatively low overall preference was at odds with a recent experiment from our lab [46] interconnected standard cages, one containing a regularly renewed Kleenex, a running wheel, and a wooden stick smeared with peanut butter, spent the bulk of their time in the enriched rather than standard cage. The lack of food treats in the current study may be one reason, but another likely reason is the regular rotation and renewal of novel objects in this experiment-a characteristic of many enrichment paradigms in common use.…”