The main objective of this research was to evaluate the quality of green mass, hay and silage prepared from perennial ryegrass Lolium perenne and tall fescue Festuca arundinacea, grown in monoculture in the experimental plot of the “Alexandru Ciubotaru” National Botanical Garden (Institute), Chisinau, Republic of Moldova. It was established that the concentration of nutrients and energy in whole-plant dry matter of studied grass species, harvested in pre-flowering stage was 10.74-14.10% CP, 3.10-3.58 % EE, 29.95-31.66% CF, 36.35-45.76% NFE, 6.20-19.24 % sugar, 1.54-2.99 % starch, 10.45-14.31% ash, 2.9 g/kg Ca, 2.5-2.7 g/kg P, 8.93-9.49 MJ/kg ME and 4.97-5.06 MJ/kg NEl. The biochemical composition of the prepared silages was: pH= 4.06-4.21, 27.9-28.9 g/kg lactic acid, 0-0.4 g/kg butyric acid, 1.5-5.0 g/kg acetic acid, 9.12-9.67% CP, 3.37-3.99% EE, 39.16-41.30% CF, 30.53-37.37% NFE, 0.33-1.40 % sugar, 0.50-0.60 % starch, 10.98-14.51% ash, 36.34-56.33 mg/kg carotene, 8.31-9.53MJ/kg ME and 4.48-5.34 MJ/kg NEl. The nutritive value of prepared hay: 9.95-10.84% CP, 1.87-2.55 % EE, 36.90-37.32% CF, 38.48-39.99% NFE, 10.8211.28% ash, 2.5-3.5 g/kg Ca, 2.6-2.7 g/kg P, 8.31-8.85MJ/kg ME and 4.54-493 MJ/kg NEl. The studied grass species contain a lot of nutrients, which make them suitable to be used as multi-purpose feed for livestock.