Responses of rats (Rattus norvegicus) to enrichment objects (1994)

Orok-Edem, E., Key, D.

Abstract

The [conventional] rat box is a two dimensional environment in which the rats can only move within the horizontal plane ... This captive environment, chosen because of ease of husbandry, hygiene and economy leads to boredom and monotony with ensuing fighting and chewing of bars. ... The well being of the rats is affected, hence experimental results are compromised. Two objects, a tongue depressor made of birch wood and a wooden block constructed of a stainless steel clip and cut broom handle were each introduced into two groups while the third groups serves as control. The hanging block was hung in the cages throughout the five day study period, while the tongue depressors were replenished each night. The objects provided both temporary (tongue depressors) and long time enrichment (hanging block), through increased contact between the rats themselves and the objects, thus enhancing social and physical interaction. The two enrichment objects encouraged natural behaviour like gnawing of the block which should reduce the incidence of overgrowing teeth. Aberrant behaviours like fighting and chewing of metal cage bars were drastically reduced.