Studying the behavioural patterns of animals in their house may help to understand their needs, but there has been a little investigation of home-cage behaviours in commonly used inbred strains of mice such as C57BL/6 and DBA/2. Therefore, understanding behavioural patterns in these mice is important for neuroscience research. For the first time, this experiment was carried out to investigate the long-term effects of housing conditions (single vs. group) on home cage behaviour of C57BL/6 and DBA/2 mice, in order to reveal differences between C57BL/6 and DBA/2 in home-cage behaviours and in response to single-housing. Sixty-four mice (32 mice/strain) were housed either singly (SH) (n= 32) or in four groups, each group contained 8 animals. Home cage behavioural patterns were recorded weekly using ethogram-based instantaneous sampling for 5 consecutive weeks. Regardless of strain, single housed (SH) mice displayed higher levels of grooming and bedding directed-behaviours and were more frequently seen in-the-crawl ball, and had lower levels of feeding behaviour compared to their group housed (GH) conspecifics. There were significant strain differences in anxiety-related behaviours with the DBA/2 strain demonstrating higher levels of sleep, feeding and grooming behaviour and frequent presence in-the-crawl ball, and lower levels of exploration, locomotion and bedding-directed behaviour compared to the C57BL/6 strain. The results therefore suggest that different housing systems influence home cage behaviours of laboratory mice with the mice of the DBA/2 strain appearing more anxious. These findings may also have great implications for researchers to decide the most appropriate phenotype to use in measuring neural response-relevant behaviours in novel animal/human models.
