In Bulgaria the research team of Sericulture Experiment Station,VratzaVratzahas made detailed research work on the has identification and evaluation of the silkworm rearing waste products. It was estimated that the silk production performs only 8.54 % from the dry matter mulberry leaf yield obtained by one hectare plantation. On the other hand the different wastes such as leaf remnants, excrements and the pupae give 2061.60 kg of dry matter or 83 %.