Longitudinal Study of Changes in Ammonia, Carbon Dioxide, Humidity and Temperature in Individually Ventilated Cages Housing Female and Male C57BL/6N Mice during Consecutive Cycles of Weekly and Bi-Weekly Cage Changes.

Using the same approach, we analysed the effects of day and night (i.e., circadian rhythm) and found a discrete, but consistent difference with significantly higher values at nighttime in the cages with the males ( p = 7.4 × 10 −16 ); in the cages with the females this covariation was smaller and only weakly significant ( p = 3 × 10 −2 ) (see Supporting Materials, Figure S3 ).

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