Substitution of cellulose with ethyl-, methyl-, hydroxypropyl-, hydroxypropyl-methyl- and carboxymethyl groups may increase the resistance of cellulose to degradation. Resistance increases with the degree of substitution and is greatest when the substituent groups are evenly dispersed along the polymer chain. Most cellulose of the additive under assessment will therefore pass the intestine undigested and will excreted unchanged via faeces. Even when a high cellulolytic activity is present, as in the rumen, ethyl cellulose remains sufficiently resistant to degradation to be used as enteric coatings designed to protect methionine from rumen release (EFSA FEEDAP Panel, 2012c). Subsequent degradation in the post-ruminal tract is most likely to lead to high molecule weight breakdown products, with little probability of absorption.