The studies were conducted in a forest settlement in Roztocze National Park (eastern Poland). The aim of the study was to evaluate the vegetation of two pastures depending on the type of use in the context of grassland protection, identify the trends of species composition changes, and analyse the yield and nutritional value of the biomass in the context of animal welfare. The studies were conducted on permanent grasslands varying in terms of fertility and location. Both sites were pastures where native breeds of livestock (Polish Lowland sheep of the Uhrusk and Polish Konik) were grazing. The fertile pasture was represented by the developing Lolio-Cynosuretum association, while the poor dry pasture – by a community with Common Bent (Agrostis capillaris L.) and a community with Mouse-Ear Hawkweed (Hieracium pilosella L.). The greatest changes over time were observed in the mowed site in the fertile pasture (increased share of tall grasses) and in the abandoned poor dry pasture (increased share of herbs and weeds). Livestock grazing conducted from 2010 influenced the stabilisation of the species composition. Tree and shrub seedlings were systematically eaten by livestock, which evidences a positive impact of grazing on the preservation of permanent grasslands in Roztocze National Park where forest ecosystems predominate. The assessment of the species composition and yielding indicated that the fertile pasture was characterised by good value while the poor pasture – low or sufficient value. In terms of nutrient yield and content, these pastures were poor or very poor, and their nutritive potential was largely dependent on the meteorological conditions. While the livestock density in the pastures, ranging from 1.1 to 1.5 LSU ha–1 in the years under study, was appropriate, grazing should be limited in the summer months, particularly in periods of drought, by reducing the number of animals or by additional feeding to ensure their welfare.