The objective of this experiment was to determine the effects of feeding different combinations of true protein (TP) and non-protein nitrogen (NPN) when forage to concentrate (F:C) is manipulated on nutrient utilization in precision-fed dairy heifers. Eight ruminally fistulated Holstein heifers (386 ± 9.1 kg BW) were randomly assigned to 2 concentrate levels: HC (25% forage) and LC (75% forage) and to a combination of TP and NPN sequence [U:C; 0% from urea U, 100% casein C (0% U, 100% C; 33% U, 67% C; 67% U, 33% C; 100% U, 0% C)] within concentrate level administered according to a split-plot, 4 × 4 Latin square design (21 d periods). Data were analyzed using the PROC Mixed procedure from SAS. Intake of N was similar and use U and C to provide 1.80 g N/kg BW 0.75. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) apparent digestibility (AD) were positively affected in HC diets (P ≤ 0.05). ADF AD linearly increased (P < 0.01) in HC, and the opposite occurred in the LC group. Fecal N, urine N, and total excreted N were reduced (P ≤ 0.05) in the HC treatment (TRT) which resulted in an increased retained N. No U:C effects were observed in AD of DM, OM, and NDF, but N AD, N (% of intake), N (% of digested) decreased linearly as U level increased (P < 0.05). A quadratic interaction (P < 0.01) was observed; decreasing total excreted N and retained N (g/d) in the HC and the opposite in LC. Total purine derivatives (PD) were positively affected by the HC group (P = 0.04) but did not affect microbial protein flow. There was a positive quadratic (P < 0.01) response in total PD as U increased in both F:C TRT. Protozoa numbers were higher in the HC diets (3.3 × 105 vs. 2.8 × 103; P < 0.01) and increase quadratically (P < 0.01) with U inclusion. No effects for ruminal NH3N between F:C TRT was observed, but there was a linear increase (P < 0.01) as U level increased. Ruminal pH was lower for HC diets (6.3 vs. 6.6) and there was a quadratic interaction as U increased. Nutrient utilization was significantly affected by manipulation of F:C and U:C.