Maternal behaviour in the laboratory mice C57BL/6J housed in a furnished environment : a pilot study

Abstract: Maternal behaviour covers a wide range of behaviours and is one important factor that can increase survival. Behaviours such as nest building, nursing, licking, lifting or moving pups, retrieving, and protection of the young are often included when measuring maternal behaviour. Commonly, observations of maternal behaviour are made on mice housed in barren cages. These cages contain nothing but sawdust and do not provide the animals with the opportunity to hide, to build nests or to make burrows. Mice are highly explorative animals and the barren environment thus restrains the animals from performing many natural behaviour patterns. In the present study, maternal behaviour was observed in the inbred strain C57BL/6J mice, housed in a furnished environment. In this study "furnished" refers to larger cages that, except from sawdust, also contained nest material, nest box, a paper tube and a chew block. The following comparisons were made: Effect of days - comparing prepartum/postpartum/day three postpartum; Effect of disturbance - comparing day three and four postpartum (before and after a pup retrieval test); Difference between Day and Night – comparison between light/dark period (on day three and four postpartum). Besides behavioural observations, the present study also aimed to investigate the best possible way of providing cage furniture, while maintaining the possibility to carry out behaviour observations. The results from the behavioural observations show that females spend significantly more time on nest behaviours after parturition compared to prepartum day and day three postpartum. Furthermore, they spent significantly more time self-grooming before parturition than postpartum and day three postpartum. There were no differences found in the behaviour following disturbance due to a pup retrieval test. Neither where there any differences found between behaviour during the light and dark period on day three or four after parturition. Since mice build complex nest structures of available material in the cage, observing maternal behaviour in furnished cages is a difficult task. The females in the present study were filmed from four different views, all which had different advantages. Depending on which behaviours that are of interest, one must choose to film from a view that gives best possibility to observe the behaviours of current interest.