Lysine is the first limiting amino acid in most cereal-based animal diets. That single fact drives one of the largest fermentation industries in the world – and it explains why there are two commercial forms of the same molecule: the purified hydrochloride and the concentrated fermentation product known as L-lysine sulphate (CAS 60343-69-3).
This guide covers what L-lysine sulphate is, how it is made, what the specification numbers mean in a feed mill, how it compares with the hydrochloride on cost and handling, and how formulators actually use it to reduce crude protein without losing performance.
What Is L-Lysine Sulphate?
L-Lysine sulphate is what you get when you do not purify the fermentation broth. The fermentation produces L-lysine; instead of isolating and crystallising it as the hydrochloride, the broth is concentrated, adjusted and dried, leaving a granular product that contains:
- L-lysine at 55% or more on a dry matter basis
- Sulphate from the neutralisation step
- Other fermentation-derived nutrients – residual amino acids, organic acids and biomass solids
- Moisture at 4% or less
That composition is the whole commercial argument: the producer skips ion exchange and crystallisation, so the product costs less per kilogram of lysine, and the feed mill gets a granular, low-dust material with a slightly broader nutrient profile.
Chemical Identity and Specification
| Item | Detail |
|---|---|
| Product name | L-Lysine sulphate, feed grade |
| CAS number | 60343-69-3 |
| Production route | Fermentation with Corynebacterium glutamicum; broth concentrated and dried |
| Lysine content | Min 55.0% on dry matter basis |
| Loss on drying | Max 4.0% |
| Appearance | Light brown to brown granular powder |
| Grade | Feed grade |
Two specification points deserve attention because they are routinely misread:
| Specification | What it really means |
|---|---|
| Lysine on dry matter basis, min 55% | The assay is corrected for moisture. A lot at 4% moisture delivers about 52.8% lysine as delivered; a lot at 2% delivers about 53.9%. Comparing two suppliers on the nominal 55% without checking moisture is comparing nothing. |
| Loss on drying max 4.0% | Both a quality and a handling parameter: higher moisture means less lysine per tonne, more caking risk, and faster mould growth in warm warehouses. |
How It Is Produced
- Fermentation. A high-yield strain of Corynebacterium glutamicum is grown on a carbohydrate source (glucose, molasses or hydrolysed starch) with nitrogen and mineral salts. Strain selection and fermentation control determine the lysine titre.
- Broth treatment. Biomass is separated or retained depending on the product route; the liquor is concentrated by evaporation.
- Neutralisation and formulation. The concentrate is standardised to the target lysine content, typically neutralised with sulphuric acid – hence “sulphate”.
- Drying and granulation. Spray drying or drum drying followed by granulation gives the granular product with low dust and good flow.
The absence of ion-exchange purification is the defining difference from the hydrochloride route. It also means the sulphate product carries the fermentation’s other soluble components, which is a nutritional bonus at a feed mill and a specification complication for anyone expecting a pure salt.
The Amino Acid Context: Why Lysine Matters
In maize-soybean meal diets for pigs and poultry, lysine is usually the first limiting amino acid – the one that runs out first relative to the animal’s requirement. Supplementing it lets the formulator:
| Effect | Mechanism |
|---|---|
| Reduce crude protein | Less soybean meal is needed once lysine is supplied; the remaining amino acids are balanced with other crystalline amino acids |
| Reduce nitrogen excretion | Lower protein intake means less nitrogen in manure – an environmental and regulatory benefit |
| Improve consistency | Lysine becomes a controlled variable rather than a function of ingredient variability |
| Lower feed cost | Soybean meal is usually the most expensive macro-ingredient; every kilogram avoided is a saving |
This is the “ideal protein” concept in practice: supply amino acids in the ratio the animal needs, with lysine as the reference.
Applications by Species
| Species | Typical inclusion (as product) | Notes |
|---|---|---|
| Swine (grow-finish) | 0.2-0.8% | Largest single use; lysine requirement falls with body weight |
| Poultry (broiler) | 0.2-0.6% | Higher lysine demand per unit feed; wheat-based diets especially |
| Aquatic (fish, shrimp) | 0.5-1.5% | High protein demand and high lysine requirement relative to terrestrial species |
| Ruminants | Rumen-protected only | Unprotected lysine is degraded in the rumen; only protected forms reach the small intestine |
Inclusion rates are indicative – the correct figure comes from the formulation matrix and the animal’s requirement, not from a supplier chart.
L-Lysine Sulphate Versus L-Lysine HCl
| Item | L-Lysine sulphate | L-Lysine HCl |
|---|---|---|
| Lysine content | 55% min (dry basis) | 78.5-78.8% lysine (98.5% HCl salt) |
| Production | Broth dried directly | Purified and crystallised |
| Cost per kg lysine | Lower | Higher |
| Handling | Granular, low dust, less caking | Fine crystalline, hygroscopic |
| Other nutrients | Contains fermentation co-products | None |
| Best fit | Cost-driven compound feed, high-volume swine and poultry | Premixes, low-inclusion applications, precise formulation |
The comparison that matters is cost per kilogram of available lysine, not cost per tonne of product. A full worked comparison is in L-lysine sulphate vs L-lysine HCl.
Formulation Notes for Feed Mills
| Point | Guidance |
|---|---|
| Convert on lysine, not on weight | Use the COA assay and moisture to calculate available lysine per tonne; do not assume 55% as delivered |
| Adjust the sulphur budget | The product carries sulphate; in diets with tight sulphur limits (some formulations target total sulphur), account for it |
| Balance the other amino acids | Reducing crude protein requires methionine, threonine, tryptophan and valine to be checked together – lysine alone is not enough |
| Storage | Keep dry and sealed; the product cakes when it absorbs moisture, and wet material is prone to mould |
| Pellet durability | Granular sulphate material generally handles pelleting well; check the inclusion rate against the durability test in your own mill |
Quality Control and Feed Compliance
| Check | What it confirms |
|---|---|
| Lysine assay (dry matter basis) | The specification value; must be normalised for moisture |
| Loss on drying | Storage quality and true delivered lysine per tonne |
| Appearance and flowability | Drying/granulation quality; caking indicates moisture pick-up |
| Heavy metals and microbiological limits | Feed safety; request the figures for your market |
| Registration status | L-Lysine sulphate is listed in national feed additive catalogues in many markets; confirm the specific rules for your destination |
Packaging and Documentation
| Item | Detail |
|---|---|
| Standard pack | 25 kg net bag with inner liner |
| Bulk pack | 1000 kg jumbo bag on request |
| Documents | COA per batch (appearance, lysine on dry basis, loss on drying), product specification sheet, SDS where applicable |
| Samples | Available for formulation and pelleting trials |
Frequently Asked Questions
Is L-lysine sulphate a pure chemical? No. It is a dried fermentation product containing lysine, sulphate and other fermentation-derived nutrients; the specification is defined by lysine content and moisture, not by purity.
Can I use it in premixes? It is used in compound feed more than in premixes because of the higher inclusion rate required; premixes usually favour the hydrochloride for its higher lysine concentration.
Does the sulphate affect the diet? It contributes sulphur. In most diets this is not limiting, but formulations with strict total-sulphur limits should account for it.
How do I compare quotes from two suppliers? Convert both to cost per kilogram of lysine on a dry matter basis, then add the handling and storage cost difference. A cheaper product with higher moisture is sometimes more expensive per unit of lysine.
Is it suitable for organic feed? Depends on the certification scheme; confirm with your certifier and request the production documentation.
Contact PolyBlueChem for specifications, samples and quotation.