21 C.F.R. § 573.420

The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions:

(a) The food additive is a cellulose ether containing ethoxy (OC2H5) groups attached by an ether linkage and containing on an anhydrous basis not more than 2.6 ethoxy groups per anhydroglucose unit.

(b) It is used or intended for use:

(1) As a binder or filler in dry vitamin preparations to be incorporated into animal feed.

(2) As a matrix scaffolding for tracers, and the ethyl cellulose content shall not exceed 80 percent of the tracer.