Characterization of Reusable and Recyclable Plastic Bedding Materials for Laboratory Mice

The scientific community has placed increasing importance on sustainability, leading to the exploration of alternative bedding materials to the widely used aspen wood chips. Bedding plays a critical role in ensuring the wellbeing of animals and the validity of experimental outcomes. Compared to the frequently evaluated biological materials, such as corncobs or spelts, synthetic materials such as plastic granules have been less investigated. We characterized two thermostable plastic materials as an alternative bedding material in C57BL/6J and BALB/c mice. We examined the impact of those bedding alternatives on physiological parameters, behavior, health status, and cage climate in static and digitally ventilated cages as well as the possibility of a reuse cycle after reprocessing. The mouse lines showed different locomotor activity, feeding, and nestbuilding behavior on plastic granules. While ammonia levels were constantly higher in static cages than in ventilated cages, blood parameters were unaltered, and health status was maintained during the reuse procedure. We show the use of plastic granulate as bedding material for mice that has the potential for processing and recycling. Further, we show that the material is accepted differently by the lines in the preference choice test without affecting their health or hygiene status.