The paper is aimed at summarising long-term studies on the effectiveness of biological ensilage stimulators containing homo- and hetero-fermentative cultures of lactic acid bacteria used in the conservation of meadow sward intended for fodder or energy production. Study material consisted of silages from wilted meadow sward ensiled in big cylinder bales wrapped in a plastic film with the addition of four bacterial preparations made in the Institute of Agricultural and Food Biotechnology: Lactosil, Lactacel-L, Lactosil Plus and Lactosil Biogaz. Control silages were made of the same plant material without additives. Studies included the assessment of aerobic stability of silages and changes in chemical composition and microbiological profile during silage samples storage in aerobic conditions. Dry mass, pH of fresh silage and the amount of lactic, acetic and butyric acids were determined in fresh silage samples and in samples after 12 days of aerobic incubation. The number of yeasts, moulds and lactic acid bacteria was determined as well. The efficiency of applied biological additives varied during the process of ensiling meadow sward, mainly due to their different composition. Lactacel-L appeared most efficient in improving fodder quality from among all applied additives. Lactosil was the best in prolonging aerobic stability. The addition of Lactosil Biogaz helped improve aerobic stability and decreased the content of lactic acid in raw material intended for energy production.