Pritchett-Corning, K. R., Keefe, R., Garner, J. P. et al. 2013. Can seeds help with the daily grind? American Association for Laboratory Animal Science [AALAS] Meeting Official Program, 609 (Abstract #PS5).
Some laboratory mice gnaw food pellets without ingesting much of the gnawed material, resulting in the production of waste material called orts. The fact that this food grinding behavior is not seen in all individuals of a particular strain suggests that it might be abnormal, and thus indicate a welfare concern. Furthermore, the increased rate of feed consumption and cage soiling is undesirable from a husbandry perspective. To try to determine possible motivations for the behavior, and identify potential treatments, outbred Crl:CD1(Icr) mice exhibiting food grinding were selected for one of 3 treatments placed in the feeder: no enrichment, a chewing device, or sunflower seeds. Both enrichment groups showed a significant decrease (P < 0.05) in ort production when compared with baseline measurements, but only mice provided with sunflower seeds maintained the decreased rate of food wastage after the treatment was withdrawn. A relationship between body weight and ort production was also found, in that cages with greater average body weights had lower levels of ort production. This suggests that a simple need to gnaw alone cannot explain food grinding, and that a nutritional motivation may also be involved.