Metabolic utilisation of amino acids (AA) regarding animal status and feed AA profile can be assessed from postprandial blood profiles. The objective of the experiment was to compare the postprandial plasma AA profile of pigs with contrasting potential for protein deposition (adult Yucatan minipigs vs growing crossbred pigs) after feeding diets either unbalanced (UNB) or balanced (BAL) in AA. For the two diets, the protein source is derived from the extensive hydrolysis of feathers, for which the resulting AA are used in different value chains. The UNB diet had a low Lys content but ratios of Met, Tyr, and His to Lys are close to the ideal profile. The ratios of the other essential AA (Cys, Thr, Val, Ile, Leu, and Phe) were unbalanced. The BAL diet was supplemented with Lys, Met, Ile, and His (plus Tyr in growing pigs) to get AA:Lys near the ideal AA profile. Experimental diets were formulated to provide the same amount of total AA by supplementing non-essential AA (Ala, Asp, Glu, Gly). Four adult and four growing pigs were fitted with a jugular catheter for serial blood collection. After an overnight fast, pigs were fed 75% of their meal allowance and blood was collected during 6 h after the meal. Each pig received each diet three times. In both stages, feeding either diet did not affect (P>0.05) total plasma AA average concentrations. Supplementation with essential AA in BAL resulted in greater (P>0.05) average plasma concentrations of Lys, Met, Ile and His, and of Tyr in growing pigs. However, supplementation of non-essential AA to both diets resulted in lower (P<0.05) plasma concentrations of Ala, Glu, and Gly (and Ser, which was not supplemented) in BAL compared to UNB. Lower Ser and Gly may be due to the use of these AA for Cys synthesis. The concentrations of Thr, Trp, and Val did not differ between diets (P>0.05). With the exception of Arg, Asp, and Tyr, growing and adult pigs responded in a similar way to balancing of the diet. In conclusion, AA supplementation to balance a diet may result in changes in plasma AA profile in growing and adult pigs. Changes in non-essential AA may be due to their roles in carbon and nitrogen metabolism.