Ferric tyrosine chelate

In the current application authorisation is sought under article 4(1) for ferric tyrosine chelate under the category/ functional group (4 b, d) "zootechnical additives"/ "gut flora stabilisers", "other zootechnical additives", according to the classification system of Annex I of Regulation (EC) No 1831/2003. Specifically, authorisation is sought for the use of the feed additive for all avian species and categories. The feed additive (ferric tyrosine chelate) is a light brown powder containing a minimum of 8.4 % iron (w/w) and 75 to 79 % (w/w) tyrosine.

The feed additive is intended to be incorporated into feedingstuffs through premixtures with a proposed minimum ferric tyrosine chelate content of 20 mg /kg feedingstuffs.

For the quantification of total iron content in the ferric tyrosine chelate (feed additive) the Applicant submitted a single-laboratory validated method derived from the official method AOAC 993.14, based on inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion. In the frame of the iron group dossiers the EURL evaluated and recommended for official control three CEN ring-trial validated methods for the quantification of total iron in feed additives: method EN 15510 based on inductively coupled plasma atomic emission spectrometry (ICP-AES); method EN 15621 based on ICP-AES after pressure digestion; and method EN ISO 6869 based on atomic absorption spectrometry (AAS).

For the quantification of tyrosine in the feed additive the Applicant submitted the ring-trial validated method EN ISO 13903, based on ion exchange chromatography coupled with post-column derivatisation and photometric detection. This method is derived from the ring-trial validated Community method, for the determination of free (synthetic and natural) and of total (peptide-bound and free) amino acids, including L-tyrosine. Based on the performance characteristics available, the EURL recommends for official control the ring-trial validated Community method, to quantify tyrosine in the feed additive.

The Applicant is aware that due to the presence of endogenous iron in feedingstuffs the direct determination of the ferric tyrosine chelate content added to premixtures or feedingstuffs is not achievable by analysis. The Applicant proposed instead an indirect single-laboratory validated and verified method, based on the enumeration of the colour coated graphite marker particles added to the feed additive for the quantification of added ferric tyrosine chelate content in premixtures and feedingstuffs. Precision ranging from 8.1 % to 17.4 % and a recovery rate (Rrec) ranging from 97 % to 113 % were reported. Based on these performance characteristics, the EURL recommends for official control this indirect method for the quantification of the added content of ferric tyrosine chelate in premixtures and feedingstuffs only if the marker added to the feed additive is clearly characterised and the inclusion content to the additive, expressed as number of graphite particles per mass of the feed additive, is specified.

Further testing or validation of the methods to be performed through the consortium of National Reference Laboratories as specified by Article 10 (Commission Regulation (EC) No 378/2005, as last amended by Regulation (EU) 2015/1761) is not considered necessary.

Recommended Method

as of:

- Commission Implementing Regulation (EU) 2024/3162

For the quantification of total iron in the feed additive:

• Inductively coupled plasma-atomic emission spectrometry, ICP-AES (EN 15510);

  or

• Inductively coupled plasma-atomic emission spectrometry, ICP-AES (EN 15621) with pressure digestion;

  or

• Atomic absorption spectrometry, AAS (EN ISO 6869)

For the determination of tyrosine in the feed additive: 

• Ion exchange chromatography method with post-column derivatisation and photometric detection (Commission Regulation (EC) No 152/2009)

For the determination of the added content of ferric tyrosine chelate in premixtures and compound feed: 

• Enumeration of colour coated particles of the graphite coloured microtracer present at fixed mass ratio in the feed additive