Davis, H. J., Barabas, A. J., Gaskill, B. N. 2022. Titrating the preferences of altered lighting against temperature in female CD-1 laboratory mice, Mus musculus. Applied Animal Behaviour Science 246, 105541.

Aspects of the laboratory are aversive to mice, such as being housed under bright lights and at temperatures below their thermal comfort, causing stress and poor welfare. While murine thermal preferences are well understood, light preferences in mice are under studied. To address this gap, reduced light intensity was titrated against varying temperatures. We hypothesized that mice would choose the red-tinted cage when offered temperatures below 30 °C but would choose the clear-heated cage when around 30 °C. Seven pairs of female CD-1 mice were randomly allocated to two connected cages (a red-tinted cage and a clear cage with a heated hot spot) for eight days, each containing 8 g of nesting material. Every 48 h, the clear, hot spot cage temperature was changed to 20, 24, 28, or 32 °C, in a random order, without repetition. Over the 8-day study, all cages experienced the 4 treatments for 2 days each. After an initial 24 h of exposure, nest complexity was scored, the amount of nesting material was weighed in each cage, and inactive behavior was observed. Temperature did not significantly alter nest weights; however, it did impact nest scores, with more complex nests being built in the red cage when 20–28 °C were available. Further, mice spent more time in the red-tinted cage when they had access to 20 and 24 °C. These temperatures do not outweigh the preference for lighting conditions, thus aversion to typical laboratory lighting may be more important than previously assumed.

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