Improving N efficiency can be achieved in dairy cows by more precisely supplying amino acids (AA) relative to requirements which necessitates accurate supply estimates of individual amino acids from feedstuffs. This study was conducted to determine absorption of individual AA from various feedstuffs. Seven heifers (258 ± 28 kg BW) were assigned to 8 treatment sequences in a 7 × 8, incomplete, Latin square design. Treatments were a control base diet (BD) plus 10% (DM basis) corn silage (CS), grass hay (GH), alfalfa hay (AH), soybean hulls (SH), dried distiller grains (DDGS), wet brewer grains (BG), or corn grain (CG)). Each period was 10 d. The base diet contained a mix of corn silage, dry hay, and soybean meal. The crude protein content for AH, BD, BG, CG, CS, DDGS, GH, and SH diets were 22.5, 23.1, 23.3, 21.8, 21.8, 23.5, 22.0, and 22.1% respectively. Blood AA entry rates were estimated for each AA by fitting a 4-pool dynamic model to blood ¹³C AA enrichment over the course of a 2h ¹³C algal AA infusion. Dry matter intake tended to be lower for BG diet (P = 0.072) and N intake was lower for CG, CS and GH diets (P < 0.01). Apparent total-tract N digestibility was 64.7 ± 4.6%, without significant difference among treatments. The plasma entry rates of Ile, Leu, Lys, Met, Phe, Thr, and Val were 5.61, 5.99, 5.90, 5.74, 5.61, 5.83, 5.76, and 5.87 mmol/min for AH, BD, BG, CG, CS, DDGS, GH, and SH, respectively, and no significant difference was detected among treatments. For nonessential AA (Ala, Asp, Pro, Tyr, Glu, Gly), the plasma entry rates were 14.00, 14.84, 15.18, 15.25, 14.31, 17.51, 13.56, and 14.20 mmol/min for AH, BD, BG, CG, CS, DDGS, GH, and SH respectively, and DDGS had trend to be higher (P = 0.075). Given the derived AA plasma entry rates, the individual AA supply by ingredient can be determined by regression in future work.