Behaviour of rats in their home cages: Day time variations and effects of routine husbandry procedures analysed by time sampling techniques.

The behaviour of laboratory rats in their home cages was observed on both the mornings and
the afternoons of days when cages were cleaned and compared to days when cages were not
cleaned. Two different time sampling methods, 'instantaneous sampling' and 'one/zero
sampling', were used and compared. In general the rats were more active in the mornings than
in the afternoons. Activity, particularly locomotion and that associated with manipulation of
the bedding was increased during both the mornings and the afternoons of cleaning days.
Defaecation also increased on cleaning days whereas sitting decreased. The cleaning regime
appeared to have a greater effect on behaviour than did time of day and the effect of cleaning
lasted for several hours after the procedure had been completed. The implications for
experimental design are discussed.