MT6001

In the rabbit hindgut, fermentation occurs through a wide prevalence of Bacteroides that do not allow an extended digestibility of fibre. Digestibility of cellulose was shown to amount to 16% of the administered dose, whereas values of 14% and 18% were reported for fibre (cellulose being the main component) (review from the NRC, 1977). Later studies reported values comprised between 15 and 25% in rabbits administered different plant sources of cellulose (Gidenne and Perez, 1996; Chiou et al., 1998). In the horse, digestion of plant structural carbohydrates (including cellulose) occurs in the hindgut (colon and overall caecum). The microbiota of the caecum comprises bacteria similar to those of the rumen, but specific protozoa. The resulting digestibility is about two-third that measured in ruminants.

Moreover, the FEEDAP Panel also noted that methyl cellulose and carboxymethyl cellulose have been used for a long time as vehicles for non-water-soluble substances in several in vivo genotoxicity assays and are recommended for this use by the current OECD test guidelines (e.g. TGs 474, 475, 478 and 483). Based on the available experimental data, neither microcrystalline cellulose nor modified cellulose (including HPMC) raise concern for genotoxicity.