Introduction One of the major problems of revitalization and development of animal husbandry is increasing and diversifi cation of forage production which can provide a guaranteed fl ow of balanced food, in terms of quantity and quality, throughout the year, according to the physiological requirements of animals. At the moment, the raw materials for silage are the annual crops: maize and sunfl ower, but, in recent years, their surface has been reduced signifi cantly and their productivity decreased because of drought and heat. The herbaceous perennial plant species with intensive growth which provide animals with qualitative fodder is giant knotweed or Sakhalin Knotweed Polygonum sachalinense F.Schmidt  syn. Fallopia sachalinense Ronse Decr., Reynoutria sachalinense Nakai originating from the spontaneous fl ora of the Far East of Russia and northern Japan were brought to Europe in the second half of 19th century and introduced into culture during the 20th century, as promising species due to their tolerance to pedoclimatic factors and stable production, are investigated and implemented in Germany, Russia, Ukraine, Belarus, Kazakhstan, China not only as a source of obtaining fodder, but also as raw material for the pharmaceutical industry and bioenergetics. The aim of the present study was to evaluate fodder value of silage from giant knotweed plants. Material and methods The giant knotweed cultivar Gigant created  in the Botanical Garden (Institute) of the ASM (2,4) and registered in 2012 in the catalogue of plant varieties of Republic of Moldova served as object of study. The biomass was collected in fi rst cut (27.05.2013) from experimental cultures and  was preserved (ensiled 60 days), were examined fodder value: chemical composition and the content amino acids, pH, the content of acids  lactic, acetic, butyric of the silage(1,3). Results and discussions The giant knotweed plants silage at the fi rst cut is characterized by a fairly good quality; it has a pleasant smell like pickled apples, olive gray colour, and perfect consistency at conservation. Ensiled biomass had a relatively optimal pH= 4.23. It was found that the content of dry matter in the silage constitute 23.80%. The dry matter of the silage contains 16.83% raw protein, 3.39% raw fat, 33.59% raw cellulose, 39.15% nitrogenous free extractive substances, 7.04% ash, and 1.08 % organic acids. In the silage butyric acid was not identifi ed, and the lactic acid is predominant and represents 72.3% of the organic acids. The fodder value of silage in this period is 9.07 nutritive units and 9.07 MJ of metabolizable energy per 1 kg of dry matter. The provision of digestible protein is of 156.78 grams per nutritive unit. Result of  essential amino acid content (g/kg dry mass): threonine, 9.52; valine, 10.20; methionine, 1.38; isoleucine, 7.48; leucine, 11.18; phenylalanine, 10.48; histidine, 4.58; lysine, 9.03; arginine, 4.65 and tryptophan. Conclusions The tests we performed, in conditions of research and production, show that the Giant knotweed plants (Polygonum sachalinense), cv. Gigant fi rst cut can be successfully used as silage.