Eighty-four high- and moderate-yielding Friesland/Holstein cows were divided into four groups and fed ad libitum complete diets with crude protein levels of: Treatment 1, 16% (4 – 33 weeks postpartum), positive control; Treatment 2, 16% (4 – 17 weeks), 12% (1,4% urea) (18 – 33 weeks); Treatment 3, 16% (4 – 17 weeks), 12% (18 – 33 weeks); and Treatment 4,12% (1,4% urea) (4-33 weeks), negative control. Milk yields for the high producers on Treatments 1, 2 and 3 were 26,7; 26,8 and 26,1 kg/day respectively, differences being not significant. However, these cows produced significantly (P < 0,01) more milk than those on Treatment 4. Milk yield declined at a rate of 1,8% per week after reaching peak production for high producers on Treatments 1, 2 and 3, and 1,4% for cows on Treatment 4. Milk production for moderate producers showed the same tendency towards dietary treatment as the results obtained with the high producers. High-producing cows on the 16% crude protein diets had a significantly (P < 0,05) higher feed intake between 4 -17 weeks postpartum than cows on the 12% crude protein (1,4% urea) diet. During the 18- 33-week period differences in dry matter intake were not significant between dietary treatments. Results indicate that 1,4% urea can be included in complete diets for high-producing cows from the 18th week postpartum with great economic advantages.