The aim was to verify the design of the technology of preservation of medium-difficult forage silage with high dry matter over 50% into round giant bales by applying citric acid in combination with bacteria Lactobacillus plantarum. The technology was successfully tested in pilot conditions on the farm of Mr. Pavel Vávra in Hrusice. The produced feed with the designation „haylage“ was subsequently fed to Texel sheep. The hypothesis was confirmed, which consisted in the assumption that citric acid will prolong the aerobic stability of the produced silage in giant bales for at least 7 days, resp. 2 days longer than control packages without preservatives.