UC Davis

Little research has been conducted to examine the influence of various methods of providing nest materials-such as dispersing them, providing them as single units, or clustering them-on the behavior and welfare of group-housed mice. In this study, 6 wk-old C57BL/6NCrl mice were housed 3 per cage and randomized into 1 of 3 nest-material groups: 1) one facial tissue per cage (control; female mice, 3 cages; male mice, 3 cages); 2) an 8-g 'puck' of compressed nesting material and a facial tissue (females, 3 cages; males, 3 cages); or 3) 8 g of dispersed paper strips and a facial tissue (females, 3 cages; males, 3 cages). Mouse behavior (agonistic, stereotypic, nesting), physical examination data, and nest scores were evaluated over 16 d. The results showed that mice in the puck and control groups spent more time manipulating nest materials after cage changes than did mice in the paper-strip group. Average nest scores were highest in the paper-strip group compared with controls and puck cages. Female cages with pucks showed no barbering, whereas all other female mice cages demonstrated barbering. Overall, nest pucks may provide a time-consuming activity for mice and may help protect female C57BL/6 mice from barbering. However, more research is needed to replicate and expand these study results.