Ruminant farm animals contribute significantly to global greenhouse gas (GHG) emissions, but the emissions can be greatly reduced by nutrition. Sustainable dairy cow feeding strategy to mitigate GHG and N emissions should make the most of the unique ability of ruminants to convert local human-inedible biomass to high-quality dairy foods. In this chapter, we review the potential of silage plant species (grass, forage legumes, maize) and stage of maturity of silage crops as well as dietary forage to concentrate ratio to reduce environmental footprint of dairy cows in the temperate areas without compromising animal performance. Dairy cow performance is examined in terms of feed intake, milk yield, feed and N efficiency, and methane emission intensity. The role of concentrate composition (lipids, carbohydrates and protein) is also evaluated. As a case study, the potential of milled rapeseed to reduce environmental footprint of grass silage-based diet is evaluated in practical farm conditions.