Quality as referred to in this project is in terms of undegradable protein, water soluble carbohydrates (WSC) and fatty acid composition of roughages. Higher amount of undegradable protein and WSC results in a more balanced protein/energy-ratio, which implicates lower emission of nitrogen. Polyunsaturated fatty acids (PUFA) are beneficial to human health. Fatty acid composition, ensiling, plant secondary metabolites and enzymes possibly influence the amount of PUFA in forage and consequently in milk.