Method for treatment of mulberry leaves for feeding silkworms in order to obtain a feedstuff for silkworms, doped with at least a metal selected among silver and/or zinc, comprising the steps of: a. preparing a solution comprising water, a photo-reducer agent and a precursor of said at least metal； b. treating said mulberry leaves with said solution； c. exposing said treated mulberry leaves to UV radiation, so that the photo-reduction of said precursor of said at least metal occurs, with the consequent deposition on said leaves of nanoparticles of said at least metal.
