What is lysine?
Lysine is one of the 20 amino acids that make up proteins. It has a second amino group on its side chain, which makes it a basic amino acid. Animals cannot synthesise lysine in their own tissues, so it is classed as an essential amino acid and must come from the diet.
Cereal grains such as corn, wheat and barley are low in lysine, while soybean meal and animal proteins are richer sources. Because muscle protein contains a high proportion of lysine, lysine supply is closely linked to lean tissue growth.
What does it do in animal feed?
- Pigs: usually the first limiting amino acid; it drives lean growth, daily gain and feed conversion, and sow milk production.
- Broilers: second limiting after methionine; important for breast meat yield and feed efficiency.
- Layers: supports egg mass and egg weight.
- Dairy cattle: together with methionine, one of the amino acids that most often limit milk protein synthesis.
- Ideal protein: lysine is the reference amino acid; the requirements for the other essential amino acids are commonly expressed as ratios to digestible lysine.
Forms of lysine
- L-lysine HCl (monohydrochloride): a crystalline powder, typically at least 98.5% pure, which corresponds to about 78% lysine. The most widely used form.
- L-lysine sulphate: a granular fermentation product that contains lysine together with other fermentation by-products; its lysine content is lower than that of lysine HCl (commonly around 55% or more, depending on the product) and should be taken from the supplier's specification.
- Liquid L-lysine: an aqueous solution (commonly about 50% lysine base) dosed through liquid systems at the feed mill.
- Rumen-protected lysine: coated or otherwise protected forms for ruminants, designed to pass the rumen and be absorbed in the small intestine.
- All feed-grade L-lysine is produced by bacterial fermentation; product forms differ in lysine content, so formulation must use the actual lysine value of each product.
How is the lysine requirement set?
Lysine is formulated on a standardised ileal digestible (SID) or digestible basis rather than on total content. The requirement depends on species, genetics, age, sex, production stage and energy density of the diet; for this reason it is often expressed as grams of digestible lysine per megajoule or megacalorie of energy.
Synthetic lysine covers the gap between what the raw materials supply and the target level. Using it allows lower crude protein diets, which can reduce nitrogen excretion and raw material cost while keeping the amino acid balance.
Quality criteria
- Guaranteed lysine content and purity (e.g. at least 98.5% L-lysine HCl).
- Moisture, ash, heavy metals and microbiological quality.
- Particle size and flowability: lysine HCl can absorb moisture and cake, which affects dosing accuracy and mixing.
- For lysine sulphate and liquid lysine: lysine content per batch, density (liquid) and consistency.
- Certificate of analysis (CoA) and lot traceability.
CTF Premix and lysine
Lysine can be included in CTF Premix's vitamin, mineral and custom premixes according to the customer's formulation, together with other amino acids, vitamins and trace minerals. Our premixes are produced at our Ankara facility under ISO 9001:2015 and GMP, and every lot has a certificate of analysis and full lot traceability.
This page is for general information. Inclusion rates and product choice should be decided with a nutritionist, taking into account the species, the feed formulation and the applicable regulations.