What is methionine?
Methionine is one of the 20 amino acids that make up proteins, and it contains sulfur. Because animals cannot synthesise it, it is classed as an essential amino acid.
Methionine is also the precursor of other sulfur compounds such as cysteine and taurine, and through S-adenosylmethionine (SAM) it serves as a methyl donor in many metabolic reactions.
What does it do in animal feed?
- Growth and meat yield: needed for protein synthesis; a shortage reduces weight gain and feed efficiency.
- Feather growth: feather protein is rich in sulfur amino acids, so methionine directly affects feather quality in poultry.
- Egg production: in layers it is a key factor for egg weight and output.
- Milk protein: in dairy cows it is, together with lysine, one of the amino acids that limit milk protein synthesis.
- Metabolism: as a methyl donor it supports liver metabolism and antioxidant defence (glutathione).
Forms of methionine
- DL-methionine: a powder, usually at least 99% pure; the most widely used form.
- Methionine hydroxy analogue (MHA): available as a liquid free acid (about 88%) or a calcium salt (about 84%). Different values are reported for its bioefficacy relative to DL-methionine; the value used in formulation should be based on supplier data and the nutritionist's assessment.
- L-methionine: the natural isomer, produced by fermentation or enzymatic processes.
- Rumen-protected methionine: coated or chemically protected forms for ruminants, which pass the rumen intact and are absorbed in the small intestine.
How is the methionine requirement set?
In formulation, methionine is usually assessed together with cysteine (total sulfur amino acids, TSAA) and on a digestible amino acid basis. Requirements vary with species, age, production stage and target performance. Synthetic methionine is added to cover the shortfall left by methionine from the raw materials.
Quality criteria
- Purity / active content (for example at least 99% for DL-methionine).
- Moisture, heavy metals and foreign matter.
- Particle size and flowability: important for even distribution in premixes and feed.
- Certificate of analysis (CoA) and lot traceability.
CTF Premix and methionine
CTF Premix can prepare premix solutions that combine amino acids with vitamins and trace minerals according to the customer's formulation. Requests for custom premixes containing methionine are evaluated with our technical team, taking the target species and inclusion rate into account.
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.