The limiting amino‐acids in groundnut meal provided at optimal and suboptimal protein levels to growing chickens

When groundnut meal, providing 12 and 24% protein levels in the diet of growing chickens, was supplemented with lysine, methionine and threonine, lysine was the first limiting amino‐acid at both protein levels. At the 12% protein level, threonine was the second and methionine the third limiting amino‐acid; at the 24% protein level, methionine was the second limiting amino‐acid and threonine was not limiting. Groundnut meal at a suboptimal protein level (12%), supplemented with the three limiting amino‐acids, gave a NPU value essentially equal to those obtained with good‐quality fish meal. Methionine, added in combination with lysine and in the absence of threonine, depressed growth below that obtained with lysine as the sole amino‐acid supplement.