The objective of the study was to determine whether non-essential amino acids (NEAA) in the form of wheat gluten (WG) have a threonine (Thr)-sparing effect in young pigs and to assess the response of hepatic and pancreatic Thr dehydrogenase (TDG) on the increase of Thr and NEAA supply. In Experiment 1, the standardized ileal digestibility (SID) of protein and amino acids (AA) in three low-Thr diets containing 20.4, 40.4, or 60.4 g of WG protein per kilogram of respective WG20, WG40 and WG60 diets, were determined on male pigs with an initial body weight (BW) of 20 kg. In Experiment 2, the effects of four Thr levels (5.1, 5.7, 6.3 and 6.9 g SID Thr per kg) and three WG levels in diets covering requirements for other SID essential AA, on nitrogen retention and TDG activity in the liver and pancreas were studied. The experiment was performed over 20 days on 72 male pigs with an initial BW of 12.5 kg, six pigs per treatment. Nitrogen retention was not affected by either the Thr level or by interaction of Thr and WG levels. It was greater in pigs fed the WG40 and WG60 than WG20 diets. TDG activity in the liver was not influenced by the dietary Thr level and in the pancreas it was the lowest in pigs fed the diet with the lowest Thr concentration, but this was not dose dependent. The WG level influenced TDG activity in both organs differently: in the liver TDG was the greatest in pigs fed the WG60 diet, while in the pancreas it was greater in pigs fed WG20 than WG40, but not WG60. The results do not evidence a sparing effect of NEAA provided by WG on Thr utilization for protein deposition and do not support the hypothesis on TDG activity as a potential unequivocal indicator of the Thr oxidation rate.