EU Proposes New Testing Rules for L-Threonine in Animal Feed Additives

A new authorisation request has been submitted for L-threonine, an amino acid used in animal feed. The additive, produced through fermentation with Escherichia coli CCTCC M 202447, is intended for all animal species. Regulators have now outlined recommended testing methods for its identification and measurement in different feed types.

The European Union Reference Laboratory (EURL) has provided guidance on how to verify its purity and concentration in various applications. The authorisation falls under Article 4 of feed additive regulations, classifying L-threonine as a nutritional additive within the amino acids, their salts, and analogues group. The product must meet a minimum purity of 98% to comply with standards.

For identification, the EURL recommends using the Food Chemical Codex 'L-threonine monograph'. When testing premixtures and feed additives containing over 10% threonine, the EN ISO 17180 method (based on IEC-VIS/FLD) is advised. Meanwhile, compound feed and water should be analysed using the Commission Regulation (EC) No 152/2009 method (IEC-VIS).

For water samples, two additional methods—AOAC 999.13 and VDLUFA 4.11.6—are suggested, both relying on IEC-VIS/FLD techniques. The limits of quantification (LOQ) have also been set: 0.03 g/kg for free threonine and 0.2 g/kg for total threonine in feedingstuffs.

The additive can be incorporated in multiple ways: mixed into premixtures, added to complementary feed, or directly included in compound feed or drinking water. The proposed testing methods ensure accurate measurement of L-threonine across different feed applications. With clear guidelines for purity, identification, and quantification, the authorisation process aims to standardise its safe and effective use in animal nutrition. The next steps depend on regulatory approval under the specified category and conditions.