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| HS Code | 537519 |
| Product Name | Feed Grade L-Threonine |
| Chemical Formula | C4H9NO3 |
| Cas Number | 72-19-5 |
| Molecular Weight | 119.12 g/mol |
| Appearance | White or light yellow crystalline powder |
| Assay Content | 98.5% min (on dry basis) |
| Loss On Drying | 0.5% max |
| Heavy Metals As Pb | 0.002% max |
| Arsenic As As | 0.0002% max |
| Residue On Ignition | 0.5% max |
| Solubility | Soluble in water; sparingly soluble in ethanol |
| Ph Value | 5.0 - 6.5 (1% aqueous solution) |
| Melting Point | 256 °C (decomposition) |
| Bulk Density | 0.60 - 0.80 g/mL |
As an accredited Feed Grade Threonine factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Feed Grade Threonine is packaged in 25 kg multi-layer paper bags, with moisture-proof lining for safe transport and storage. |
| Container Loading (20′ FCL) | 20′ FCL: palletized Feed Grade Threonine in 25kg bags, stowed securely, ventilated, dry, protected from moisture and contamination. |
| Shipping | Feed Grade Threonine ships as a non-hazardous, free-flowing powder in 25kg multi-layer paper bags with PE liners, or bulk bags. Keep dry, cool, and ventilated during transport to prevent caking and contamination. Avoid direct sunlight, moisture, and rough handling to preserve product quality and feed safety. |
| Storage | Store Feed Grade Threonine in a cool, dry, well-ventilated area, away from direct sunlight, heat, moisture, and strong oxidizers. Keep containers tightly sealed to prevent caking or contamination. Avoid floor contact by using pallets. Under these conditions, the product remains stable and retains its specified quality for its intended shelf life. |
| Shelf Life | Shelf life is typically 24 months when stored in a cool, dry, sealed container away from sunlight and moisture. |
In broiler grower formulas where total crude protein is reduced from 20.5% to 18.5% to control nitrogen excretion and feed cost, maize-soybean meal rations become threonine-limiting after methionine and lysine correction. Feed-grade L-threonine produced by fermentation is regulated in the European Union under Regulation (EC) No 1831/2003 as nutritional additive 3c410; in the United States it is listed in the AAFCO Official Publication as a feed-grade amino acid ingredient. Finished feed verification commonly follows ISO 13903:2005 for amino acid analysis after acid hydrolysis and HPLC separation, with sampling and homogenization procedures aligned to ISO 6497. The critical threshold is not threonine stability itself, but the point at which intact soybean meal threonine declines while breast meat accretion requires a stable digestible Threonine:Lysine ratio. Breeder nutrient specifications for modern broiler lines routinely place digestible Thr:Lys in the 0.64–0.72 range across phases, with grower and finisher targets often between 0.65 and 0.68. When crude protein falls below 19%, threonine from intact ingredients can no longer meet that ratio, and crystalline L-threonine becomes a non-negotiable correction rather than an optional economic adjustment.
| Jurisdiction | Designation | Scope | Analytical Control |
|---|---|---|---|
| European Union | Regulation (EC) No 1831/2003, ID 3c410 | Nutritional additive, amino acids | Label declaration and ISO 13903:2005 recovery |
| United States | AAFCO Official Publication | Feed-grade L-threonine ingredient definition | Certificate of analysis against AAFCO identity and purity |
| China | GB 34466-2017 | Feed additive L-threonine specification | Purity, loss on drying, heavy metal limits |
| Method | ISO 13903:2005 | Acid hydrolysis and HPLC amino acid quantification | Replicate coefficient of variation <5% |
Formulation addition in a low-protein broiler grower line typically ranges from 1.0 to 2.2 kg/MT when soybean meal is reduced by 1.5 percentage points and the diet is balanced to approximately 1.05% standardised ileal digestible lysine. At production scale, the crystalline powder is added through a micro-ingredient batching system after the primary grain and protein meal weighments, and it is blended in a horizontal ribbon mixer with a dry-mix cycle of 3–4 min. Mixer uniformity is assessed by sampling ten points across the batch and assaying threonine according to ISO 13903:2005; a coefficient of variation below 5% is the operational acceptance limit. Conditioning at 80–85°C for 35–40 s followed by pelleting through a 1:10 to 1:12 compression die does not materially reduce free threonine recovery, provided moisture is kept below 17% and reducing sugar content is controlled. The terminal products are pelleted complete broiler grower and finisher feeds, as well as crumbled starter diets where the same threonine correction is applied at the mash stage before crumbling.
Feed for weaned piglets from 21 to 42 days of age presents a structurally different threonine demand because the small intestine allocates a large proportion of systemic threonine to mucin turnover rather than whole-body protein accretion. In this nursery application, feed-grade L-threonine is included under the same EU additive identification 3c410 and is verified in finished feed by ISO 13903:2005; analytical certificates also follow the AAFCO ingredient definition for US shipments. The formulation target is expressed as standardised ileal digestible Threonine:Lysine, commonly held between 0.62 and 0.68 for piglets in the 7–12 kg bodyweight bracket. For a diet containing 1.25% SID lysine, this usually corresponds to supplemental crystalline L-threonine addition of 0.8–2.0 kg/MT, depending on whether spray-dried plasma, fishmeal, or fermented soybean protein concentrates are present. Batch-to-batch variance in soybean meal is a genuine production bottleneck in this segment: overprocessed soybean meal with low KOH protein solubility reduces available threonine below the matrix values used in least-cost formulation, and the resulting gap is not visible until feed intake or faecal consistency signals a mismatch. On manufacturing lines, the free amino acid is introduced through a micro-dispenser into a ribbon or twin-shaft mixer, with a wet-mix period of 2 min after oil or acidified water addition. Pelleting of pres-starter feeds is deliberately run at 65–75°C to protect heat-sensitive plasma fractions and organic acids, but threonine recovery remains close to feed-grade input at this range. The terminal product types are crumbling pres-starter pellets and mash starter feeds for nursery housing systems.
Layer rations differ from broiler feeds because threonine is simultaneously used for egg albumen synthesis, intestinal mucin renewal, and maintenance during fluctuating daily feed intake. For brown-egg strains in peak lay, commercial layer nutrition models commonly set digestible threonine intake between 0.42 and 0.48 g/hen/day at a 60 g egg mass output, with a digestible Thr:Lys ratio near 0.68–0.73. The corresponding crystalline L-threonine addition in a maize-soybean layer mash often ranges from 0.3 to 0.7 kg/MT, but the exact top-up depends on phase feeding, feather renewal after moult, and whether low-protein premixes or synthetic methionine dominate the formula. Regulatory compliance in this application is jurisdiction-dependent: for exports to China, GB 34466-2017 defines the feed additive L-threonine specification, while EU feed safety assurance operates under Regulation (EC) No 1831/2003 and finished feed amino acid verification under ISO 13903:2005. Post-moult flocks are especially sensitive because voluntary feed intake recovers more slowly than egg mass demand, and a fixed threonine-to-energy matrix can underestimate the supplementation required when feed intake drops below 100 g/hen/day.
Downstream production of layer feed is dominated by mash rather than pelleted output, which reduces the heat exposure of free threonine but increases segregation risk if particle size distribution is not controlled. In a 3000 kg horizontal mixer, crystalline threonine is added after limestone and poorly flowing ingredients have been preloaded, and the mixing sequence is adjusted so that the synthetic amino acid does not stratify into the upper layer of the batch. Production records from open-house and tunnel-ventilated operations show that feed intake variability of ±8% across a flock changes daily threonine intake more than a 0.02 shift in dietary Thr:Lys, which is why some feed mills apply a dynamic intake buffer for marginal amino acids in summer ration adjustments. Terminal product types include complete mash feeds for cage systems, barn systems, and breeder rearer phases where threonine is further titrated against follicle development and albumen protein deposition.
In extruded grower diets for Atlantic salmon where fishmeal has been displaced from 30% to 12% by soy protein concentrate, wheat gluten, and faba bean protein, threonine becomes a limiting amino acid before the formula cost marker indicates deficiency. The feed-grade material is authorised in the EU as 3c410 and verified after extrusion via ISO 13903:2005; Norwegian and Scottish feed assurance schemes additionally require batch-level documentation for free amino acid recovery and homogeneity. Total threonine targets for salmonid grower feeds are usually maintained between 1.1% and 1.3% of dry matter, and the crystalline L-threonine addition typically ranges from 0.5 to 2.0 kg/MT when plant protein replacement displaces fishmeal threonine. The actual inclusion is not linear with fishmeal removal because wheat gluten and soy protein concentrate have divergent threonine-to-protein profiles, and the digestible threonine pool is further modified by antinutritional factors that reduce apparent amino acid absorption.
Manufacturing these feeds on a twin-screw extruder with an L/D ratio near 25:1 creates a specific thermal conflict. The preconditioner introduces steam at 90–95°C, and barrel temperatures reach 120–130°C in the melt zone, with specific mechanical energy between 20 and 35 kWh/t. Free L-threonine added before the preconditioner can undergo Maillard-type loss if reducing sugars from wheat hydrolysis are present at high moisture; therefore production-scale salmonid lines often direct crystalline threonine into the vacuum coating step after extrusion rather than the dry mix. Vacuum coating allows the amino acid to penetrate the oil film on expanded pellets, reducing wash-off loss and avoiding the barrel residence time that would compromise recovery. The terminal products are high-energy extruded salmonid grower pellets, either floating or slow-sinking, with post-coating fat levels that also influence threonine retention during sea transfer.
Juvenile Litopenaeus vannamei feeds formulated with fishmeal below 10% and high inclusion of dehulled soybean meal, pea protein concentrate, or corn protein concentrate require explicit threonine correction because the published requirement range for this species commonly falls between 1.2% and 1.5% of dry matter depending on rearing salinity and growth stage. Crystalline L-threonine is added at 0.5–2.0 kg/MT in such low-fishmeal grower formulas, but the actual dietary free threonine retained by the pellet can be lower than the formulated matrix value after water immersion. Compliance for this aquaculture application follows the EU designation 3c410 under Regulation (EC) No 1831/2003, with finished feed amino acid distribution verified using ISO 13903:2005. Because shrimp feeds are exposed to pond water for extended periods before ingestion, the standard laboratory assay of dry mixed feed is not sufficient as a release test; post-production leach testing is required on the production floor to confirm that free threonine is not lost at a higher rate than protein-bound amino acids from intact meals.
The production process is either steam pelleting at 90–95°C through a 1:11 compression die or low-shear extrusion into sinking pellets, followed by drying and post-coating with attractants, binders, or oil. The free amino acid leaching conflict is most pronounced when crystalline threonine is added entirely into the dry mix and the pellet lacks sufficient post-coating binder. In uncoated water-stable shrimp pellets, published data for the exact threonine leaching gradient across 60–120 min immersion is limited, but production monitoring has repeatedly shown that free amino acids leach faster than intact protein-bound amino acids from the same pellet matrix. This operational boundary forces a split addition strategy: a portion of crystalline L-threonine is added into the mash to maintain the certified analytical target, and a portion is applied in the post-coating vacuum or spray unit with a binder to slow dissolution in pond water. Terminal product types are sinking shrimp grower pellets and shatter-resistant crumble formulations used in tray and pond raceway systems.
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Feed-grade L-threonine is supplied as a white to pale-yellow crystalline powder or granular material with a minimum L-threonine assay of 98.5% on a dry matter basis. The chemical identity is C4H9NO3, CAS 72-19-5, molar mass 119.12 g/mol. Unlike racemic or mixed stereoisomer products, the feed-grade material is specified as the 2S,3R enantiomer; optical rotation is controlled between −26.5° and −29.0° measured at 20°C in a 6% aqueous solution. Two product models dominate commercial supply: standard 98.5% crystalline powder and granular fractions shaped for low-dust premix handling. Some distributors also supply a diluted variant blended with silica or calcium carbonate to improve metering in low-inclusion micro-dosing stations, but the active ingredient remains crystalline L-threonine rather than fermentation biomass. Manufacturing uses industrial fermentation with Escherichia coli or Corynebacterium glutamicum, followed by ion-exchange recovery, crystallisation, and fluid-bed drying. Regulatory authorisation is generally through national feed additive registers or the European Union Register of Feed Additives under Regulation (EC) No 1831/2003; feed-grade material is not automatically interchangeable with pharmaceutical-grade threonine because release testing follows feed-additive standards such as GB/T 21979-2008 rather than pharmacopoeia monographs. The product is used as a dry amino acid supplement in least-cost formulation for poultry and swine diets, especially when intact protein is reduced or when non-corn cereals increase dietary threonine variability.
In wheat- and barley-based broiler and pig feeds, total threonine in raw materials is lower than in corn-soybean meal formulations and the standardized ileal digestibility of threonine is more variable. Formulation based solely on total threonine underestimates the risk of a deficiency when non-corn cereals exceed 30–40% of the ration. The first practical check is the SID threonine-to-lysine ratio: growing broiler starter diets are typically corrected to a ratio of 0.62–0.66, while growing pigs from 25–50 kg often require a SID Thr:Lys ratio of 0.63–0.68 depending on genotype and lean deposition rate. If the calculated ratio falls below the lower boundary, feed-grade L-threonine crystal is added at the mix step. The addition is not fixed; it is calculated by least-cost software after setting SID threonine, SID lysine, and ratio constraints. Threonine is frequently the third constraint after lysine and methionine in corn-soy diets, and the third or fourth limiting amino acid in wheat-barley diets. Without supplemental L-threonine, crude protein reduction stalls because intact soybean meal or other protein sources remain the threonine carrier even when lysine, methionine, and tryptophan constraints are already satisfied.
Because the dry powder is recovered as the free amino acid, not as a salt or hydrated form, assay and chloride content are not the same as L-lysine monohydrochloride. A typical feed-grade release includes assay, specific rotation, moisture, ash, and trace-element limits. The release profile is given in Table 1.
| Property | Boundary | Reference basis |
|---|---|---|
| L-Threonine assay | ≥98.5% on dry matter | Ion-exchange HPLC with post-column ninhydrin, GB/T 21979-2008 |
| Specific rotation [α]D20 | −26.5° to −29.0° | Polarimetry, 6% aqueous solution |
| Loss on drying | ≤1.0% | ISO 6496:1999 |
| Residue on ignition | ≤0.5% | ISO 5984:2002 |
| Lead | ≤10 mg/kg | Atomic absorption or ICP-MS, GB/T 21979-2008 |
| Arsenic | ≤2 mg/kg | Hydride-generation atomic absorption |
Dry-mix handling is not a generic operation. Crystalline L-threonine develops electrostatic surface charge under low humidity, which increases adhesion to mixer walls and raises the coefficient of variation of the premix. In a twin-shaft paddle mixer with a fill factor of 0.60–0.70, addition of the powdered amino acid after 30% of the batch dry-mix time and before added fats or oils reduces measured CV to below 5% after 180 seconds. If the batch is discharged immediately after adding the amino acid, CV can remain above 12% because the bulk-density difference between the crystal and soybean meal is large. The powder should not be assumed to distribute like bentonite or salt; it has a low bulk density and can accumulate electrostatic charge.
Feed-grade threonine as dry crystals is thermostable under conventional pelleting conditions, but thermostability in a pure assay does not equal recovery in a complete feed. During steam conditioning at 75–85°C for 30–45 seconds, recovery of added L-threonine typically remains high because the matrix moisture content is moderate and residence time is short. The main process risk is not simple thermal decomposition; it is Maillard-type reaction between the free amino group and reducing sugars in ingredients such as wheat, barley, whey permeate, or molasses. In high-shear extrusion or expansion above 120°C with moisture above 20% and reducing sugars present, free threonine loss can exceed 5%; published data for specific extruder configurations is limited. Equipment observations from single-screw extruders with L/D 25:1 and barrel temperatures around 130°C indicate that threonine recovery can remain above 90% when preconditioner moisture is controlled below 25%, but the result should not be extrapolated to twin-screw high-moisture pet food systems. The conservative processing rule is to add crystalline L-threonine through a post-pellet liquid or powder application system when thermal exposure exceeds 100°C with added sugar or when moisture at the die exceeds 22%. If post-pellet addition is not available, the formulator should verify threonine recovery by HPLC on finished feed using ISO 13903:2005 rather than relying on theoretical input values.
Threonine is hygroscopic at high relative humidity and should not be stored in open bags under RH >60%. In premixes stored with choline chloride and trace minerals, the dry blend can undergo local moisture uptake and caking. Bags should be kept sealed and protected from direct water ingress. The powder should not be mixed with strong oxidizers or concentrated acids, because the free amino group can react or degrade. For long-term storage, a stable warehouse at 15–25°C and RH <55% is the boundary typically used in feed additive warehouses. Powder bridging may occur in bulk silos if the hopper half-angle is too shallow or if the product has been exposed to humidity cycles.
The feed-grade threonine product is structurally and nutritionally distinct from other supplemental amino acids. Lysine monohydrochloride contributes chloride ion to the dietary electrolyte balance; DL-methionine provides both methionine and a methyl-donor role; L-threonine provides neither a halide anion nor a labile methyl group. Threonine’s dietary function in monogastric animals is dominated by incorporation into mucin, immunoglobulins, and tissue protein. The comparison with threonine-rich fermentation biomass is more operationally important than the difference from other amino acids. Biomass products may contain 30–60% crude protein and variable free threonine; the crystalline feed-grade product is ≥98.5% L-threonine. When a formulation uses total threonine from biomass without SID coefficients, the actual available threonine can be overestimated. Liquid threonine concentrates, which are typically 40–50% L-threonine by weight, remove dust but require heated tank systems and dosing pumps; they add water to the mixer and are not a direct dry replacement. The dry crystalline product is preferred in dry premixes and compound feed lines where micro-dosing accuracy and low moisture ingress are the limiting constraints.
| Form | L-Threonine content | Main process advantage | Main process boundary |
|---|---|---|---|
| Dry crystalline powder | ≥98.5% | High assay, dry premix compatible | Electrostatic dust; bridging in hoppers |
| Granular dry | ≥98.5% | Lower dust, better flow | Larger particle size may segregate in very fine premixes |
| Liquid concentrate | 40–50% w/w | No dust, post-pellet spray possible | Requires heated storage between 15°C and 25°C to avoid crystallisation |
| Fermentation biomass | variable, typically <65% crude protein | Lower cost per kg of protein | Variable free threonine and SID; cannot replace crystalline L-threonine as a pure amino acid source |
Laboratory and production-scale datasets show that plasma free threonine responds less sharply to dietary threonine than to lysine or methionine because a large fraction of absorbed threonine is retained by intestinal tissue for mucin synthesis and energy metabolism. Mucin MUC2 contains approximately 11–13% threonine residues, which means intestinal mucin turnover creates a high first-pass demand. In Eimeria-challenged broilers, mucin output rises and the SID threonine requirement can exceed the unchallenged ideal-protein ratio. Formulators should not adjust threonine addition based only on plasma amino acid profiles; growth, feed conversion, and ileal digestibility coefficients are more reliable. A diagnosis of threonine inadequacy based on plasma concentration alone underrepresents the effect of mucin secretion because splanchnic retention buffers peripheral plasma values. This is one reason why the product is specified and added as an ileal-digestible amino acid constraint, not as a blood metabolite marker.
In least-cost formulation, L-threonine should be declared as a SID target rather than a total amino acid target. If the total dietary threonine is supplied by multiple byproducts, use SID coefficients from a recognized feed table and verify finished feed amino acid content with ISO 13903:2005. Avoid combining threonine supplementation with high inclusion of reducing-sugar ingredients in high-temperature processes unless recovery is verified analytically. Published data for threonine recovery in specific extruder configurations is limited; therefore, equipment-specific validation should be conducted before relying on a fixed processing margin.
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