Abstract: This invention concerns compositions for zootechnical and veterinary use, characterized in that biologically active substances are incorporated in protective matrices, which have the following properties: 1) controlled release (ruminal by-pass) effect; 2) chemical-physical protection of active principles against degradation induced by technological processes of production, storage and pellettization of fodders for all animal species. The matrices of the invention are characterized by a plastic rheological behaviour due to the presence of lipogelling agents. The obtained products show the following advantages: increased active principle stability in feeds for all animal species; protection of the active principles from attack of Rumen microorganisms in fodder from attack of for ruminants.