Comparison of Four Beddings for Ammonia Control in Individually Ventilated Mouse Cages

Ammonia control is an important characteristic of rodent bedding materials. Among natural bedding materials, corncob bedding provides excellent ammonia control but contains estrogenic compounds and is ingested by mice. By comparison, processed cellulose bedding products are biologically inert and harbor fewer bacteria but historically have shown low absorbency or poor ammonia control. New cellulose products have been developed to address these shortcomings. Over a 2-wk period, we evaluated intracage ammonia levels in mouse IVC using 4 bedding types: shaved aspen, corncob, virgin pelleted cellulose, and refined virgin diced cellulose. Ammonia levels were measured by using 3 methods: colored reagent tubes, colorimetric paper strips, and a photoionization detector. Corncob, pelleted cellulose, and diced cellulose showed better ammonia control than aspen as early as 4 d after cage changing and throughout the 2-wk measurement period. In addition, pelleted and diced cellulose products resulted in lower ammonia levels than corncob at the end of the 14-d cage-change interval. Our data indicate that pelleted or refined diced cellulose are viable alternatives to natural bedding products in IVC to limit the risk of exposure of mice to high ammonia levels.