Both grades deliver the same essential amino acid â but purity, physical form, price and application differ. Here is how feed formulators actually decide.
What is lysine and why does it matter?
Lysine is the first limiting amino acid in typical corn-soybean diets for pigs and the second for poultry. If lysine is deficient, protein deposition stalls regardless of how much total protein the feed contains. Supplementing purified lysine lets nutritionists lower crude protein, cut soybean meal inclusion and reduce nitrogen excretion â without sacrificing growth.
Commercially, lysine reaches feed mills in two dominant forms: L-Lysine Hydrochloride (HCL), standardized at 98.5% purity, and L-Lysine Sulfate, usually standardized to a 70% lysine-base equivalent.
L-Lysine HCL 98.5%: the reference standard
L-Lysine HCL (CAS 657-27-2) is a white to light yellow crystalline powder containing approximately 78.8% available lysine. Its advantages are high purity, consistent assay, low impurities and predictable formulation tables. It is the default choice for precise least-cost formulation, premixes, and customers requiring tight specification windows.
Because of its purity, HCL contributes very little non-lysine material, which keeps mineral and chloride balancing straightforward.
L-Lysine Sulfate 70%: cost-efficient granular option
L-Lysine Sulfate (CAS 60343-69-3) is a fermentation-derived granulated product containing about 55% lysine in the 70% standardized grade, plus fermentation by-products and sulfate. It is typically cheaper per unit of lysine, nearly dust-free and flows exceptionally well in bulk-blend plants.
Large integrated operations in China and Southeast Asia widely prefer sulfate for grow-finisher pig and broiler feeds where formulation tolerances accommodate the lower concentration and accompanying residues.