Straw of maize plants which had been fertilized with 40, 120 or 200 kg N/ha was fed to 27 Döhne Merino wethers in a digestibility trial. Feed residues, faeces and urine were collected over a 7-day period. Intake of dry matter by sheep increased (571, 801 and 903 g/day) With Increasing N level per ha (P ≤0;01). The N balance as a percentage of the N intake of sheep fed maize residues fertilized with 40 kg N/ha was negative (-59,8%), but those fed maize residues fertilized with 120 or200 kg N/ha had a positive (P ≤0,01) N balance (3,2 and 14,9% respectively). Fertilization increased (P≤ 0,05) the apparent digestible energy content (43,0; 45,6 and 49,5%), The apparent digestible protein (-3,3; 9,2 and 16,2 g/day) and energy intake (4,4; 6,5 and 7,9 MJ/day) increased (P≤0,01) with increasing N level per ha.