In poultry nutrition, which essential amino acid is commonly limiting in corn-soybean meal diets?

• A. Methionine.
• B. Lysine.
• C. Valine.
• D. Threonine.

Answer: (B)

In poultry nutrition, growth depends on having all essential amino acids available in the right amounts, and the one present in the smallest relative amount to the bird’s needs is the limiting amino acid. In a corn–soybean meal diet, corn supplies energy but is low in lysine, the amino acid needed in relatively large amounts for rapid growth. Soybean meal adds lysine, but even with standard inclusion, the diet often falls short of the birds’ lysine requirement. Because lysine is the essential amino acid most limiting in this common mix, it largely dictates how well the birds can grow and convert feed into body tissue. When lysine is adequately supplied, other amino acids can support growth more fully, though methionine or others may then become limiting, which is why lysine is typically the first to be addressed with supplementation.