Existing grassland-based male beef production systems use 200 to 300 kg N/ha and require 9 to 11 t silage plus 700 to 1200 kg concentrates per animal produced. Output is in the range 700 to 800 kg carcass per ha. Arising from the reform of the Common Agricultural Policy (CAP) of the European Union, such beef production systems must be extensified if all the animals are to qualify for the special beef premium. The reformed CAP specifies a maximum stocking density of 2 livestock units (LU) per ha whereas existing systems operate at an intensity of 2.5 to 2.7 LU per ha. The objectives of the present study were (1) to extensify beef production (from dairy bred calves) so as to obtain more production from grazed grass and less from silage and concentrates and (2) to measure the effects of reduced fertiliser N usage on herbage production, stock carrying capacity and animal performance.