Environmental factors (e.g. temperature, illumination) can perturb the welfare/induce distress in animals. Detailed studies on effects specifically of light in the environment are lacking. A group from the University of Oxford studied the effect of cage position relative to the illumination in the room of the rack both in Tecniplast’s transparent and red cages on animal locomotion using DVC® technology. In cage locomotion of group-housed animals was very much dependent on whether the cages were located close to the light source, namely at the top of the rack vs. the bottom. Additionally, important differences in activity were dependent on cage type (transparent vs. red) The variation was as much as 15 times comparing the top vs. bottom cages.
The author concluded that an undocumented factor such as light can result in very important variations, posing an important issue in the reproducibility of animal experiments.