The study looked at how different types of grass, nitrogen levels, and sward density affect the yield and quality of grass in a field experiment. Non-perennial grasses produced the most energy, with Lolium species having higher energy content than Dactylis glomerata. Lower nitrogen levels had positive effects on protein/energy ratios. Nitrate levels increased with higher nitrogen application, with Dactylis glomerata having the highest nitrate content. Sward density also influenced energy yield and nitrate content. The results show that different grass species and sward density can impact the quality of grass swards.