What is DL-methionine 99%?
DL-methionine is produced by chemical synthesis, which yields a racemic mixture of D-methionine and L-methionine in about equal proportions. Animals convert the D-isomer to L-methionine in the body, so feed-grade DL-methionine is used as a methionine source on a 1:1 basis in most formulation systems. For the biology of methionine and its role as the first limiting amino acid in poultry diets, see our general page on methionine.
Unlike lysine HCl, DL-methionine is not a salt: the product is almost entirely methionine, so the purity figure and the methionine content are practically the same.
Typical specification items
- Assay: DL-methionine ≥99%.
- Loss on drying: low, as stated in the specification.
- Ash / residue on ignition, chloride and heavy metals within supplier and regulatory limits.
- Appearance, particle size and bulk density, relevant to flow and mixing.
- Certificate of analysis (CoA) and lot number on every delivery.
Handling and storage
DL-methionine is a stable, relatively non-hygroscopic powder and keeps well when stored in closed bags in a cool, dry place, away from direct sunlight and off the floor. It is a fine product and can form dust during tipping and conveying, so dust extraction and normal personal protective equipment should be used in the mixing area. Its stability and small particle size make it well suited to premixes, where it distributes evenly at low inclusion rates.
DL-methionine compared with MHA and L-methionine
- DL-methionine 99%: dry powder, almost pure methionine, chemically synthesised; easy to dose in premixes and dry feed.
- MHA free acid (liquid, about 88%) and MHA calcium salt (dry, about 84%): hydroxy analogues that the animal converts to L-methionine. Different relative bioefficacy values compared with DL-methionine are reported in the literature, and the value used in formulation should be based on supplier data and the nutritionist's assessment.
- L-methionine: the single natural isomer, produced by fermentation or enzymatic processes; used on an equal methionine basis by most formulators.
- Rumen-protected methionine: a separate product family for ruminants and not interchangeable with feed-grade DL-methionine.
How doses are converted between forms
Conversion is done on a methionine-equivalent basis. Between DL-methionine 99% and L-methionine of similar purity the substitution is essentially 1:1 by weight. For MHA, two factors apply: the product's active content (for example 88% for liquid MHA free acid) and the relative bioefficacy value chosen by the nutritionist.
Example: if 1 kg of DL-methionine 99% is to be replaced by an MHA product, the amount needed is 0.99 kg methionine-equivalent divided by (active content × chosen relative bioefficacy). Because this choice has a large effect on the result, it should be agreed with the nutritionist and supplier rather than taken from a generic table.
Why the choice of form matters
Besides price per unit of methionine activity, the choice depends on the mill's equipment (liquid MHA needs a liquid dosing system), on the target species and on whether the methionine goes into a premix or directly into the feed. For premixes and smaller mills that dose dry ingredients, DL-methionine 99% is usually the most practical form.
CTF Premix and DL-methionine
DL-methionine 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.