Impact of aspen furniture and restricted feeding on activity, blood pressure, heart rate and faecal corticosterone and immunoglobulin A excretion in rats (Rattus norvegicus) housed in individually ventilated cages.

This study aims to evaluate the impact of adding different items in individually ventilated rat cages on the animal's activity, cardiovascular parameters and faecal stress indicators. The following three cage items made of aspen were compared: a cross made of two intersecting boards, a similar cross where drilled holes were loaded with food pellets (restricted feeding) and a rectangular tube. Male rats of the strains BN and F344 (n = 12) were housed in groups of three; one rat in each group was implanted with a telemetric transponder to measure mean arterial pressure (MAP) and heart rate (HR). In a crossover design, each group spent 14 days with each type of cage furniture, thereafter faecal pellets were collected for faecal analyses. The means of activity and means and coefficient of variation for MAP and HR were calculated for days 2, 6, 10 and 14. As a way of determining which of the statistically significant MAP and HR mean changes were biologically meaningful, the night-day differences of the controls on day 14 were used. Both board types lowered MAP of F344 rats; hence dividing walls seem beneficial for F344 welfare. None of the MAP or HR differences in BN rats were biologically significant. No statistically significant differences in faecal corticosterone or IgA excretion were detected. In conclusion, provision of general recommendations with respect to cage furniture for rat cages is complicated because there is a clear genetic component involved in how animals respond to these structures.