Grasses of ryegrass (Lolium) and fescue (Festuca) genera play an important role in the nutrition of high-yielding dairy cows, but fescue x ryegrass hybrids (Festulolium braunii) are also increasingly used. The growing popularity of F. braunii can be attributed to its supreme agronomic traits, combining the high yield potential of ryegrass: Lolium multiflorum and Lolium perenne, and the high resistance of fescue: Festuca pratensis, F. arundinacea and F. arundinacea var. glaucescens, to biotic and abiotic factors. The aim of this study was to analyze the composition of nitrogen fractions in the herbage of different Festulolium braunii cultivars harvested at different dates. Three F. braunii cultivars were studied: Felopa, Lofa and Perun. The chemical composition of herbage (dry matter - DM, crude protein - CP, water-soluble carbohydrates - WSC, neutral detergent fiber - NDF, acid detergent fiber - ADF) and nitrogen fractions (A, B1, B2, B3, C) were determined in accordance with the Cornell Net Carbohydrate and Protein System (CNCPS). In the analyzed forages, highly significant differences (P

24.4.2019