Effect of diet on postprandial leucine, isoleucine, valine and branched-chain amino acid (BCAA) concentrations in plasma of piglets fed Control (CON), Restricted + BCAA (RBCAA), Restricted + Leu (RL), or Restricted (R) diets for 9 (n = 24) and 21 d (n = 22). Values are least square means ± SE. *P ≤ 0.05 **P ≤ 0.01 ***P ≤ 0.001.