The experiment was aimed at assessing the fermentation and aerobic stability of silages of alfalfa (Medicago sativa), harvested with about 32 % dry matter, with different chop lengths, under use of new-type ensilaging additives. There are substances which can influence the course and result of the fermentation process or the aerobic degradation of silages either by supporting the existing microflora through a nutrient (e.g. molasses), or by reducing an undesirable microflora (tannins). The said alternative approaches were described e.g. by Greatheadem (2003), or Broderick et al. (2017).