
Article 1 
The substance specified in the Annex, belonging to the additive category ‘nutritional additives’ and to the functional group ‘amino acids, their salts and analogues’, is authorised as an additive in animal nutrition subject to the conditions laid down in that Annex.
Article 2 
This Regulation shall enter into force on the twentieth day following that of its publication in the Official Journal of the European Union.
This Regulation shall be binding in its entirety and directly applicable in all Member States.Done at Brussels, 18 October 2013.
For the Commission
The President
José Manuel BARROSO
ANNEX

Identification number of the additive Name of the holder of authorisation Additive Composition, chemical formula, description, analytical method Species or category of animal Maximum age Minimum content Maximum content Other provisions End of period of authorisation
mg/kg of complete feed with a moisture content of 12 %
Category of nutritional additives. Functional group: amino acids, their salts and analogues
3c391 — L-cystine 
 Additive composition
Crystalline powder produced by hydrolysis of natural keratin from poultry feathers with a minimum L-cystine content of 98,5 %
 Characterisation of the active substance
IUPAC name: (2R)-2-amino-3-[(2R)-2-amino-3-hydroxy-3-oxopropyl] disulfanyl-propanoic acid
CAS number: 56-89-3
Chemical formula: C6H12N2O4S2
 Analytical methods
For the determination of L-cystine in the feed additive:
Titrimetry, European Pharmacopoeia (Ph. Eur. 6.0, method 01/2008-0998).
For the determination of cystine in premixtures, compound feed and feed materials:
Ion exchange chromatography method with post-column derivatisation and photometric detection: Commission Regulation (EC) No 152/2009 (Annex III, F). All animal species — — — 
1. For user safety: Breathing protection, safety glasses and gloves should be worn during handling.

2. 

— Processing stability and storage conditions.
— Supplementation with L-cystine shall depend on the requirements of the target animals for sulphur-containing amino acids and the level of other sulphur-containing amino acids in the ration.
 8 November 2023

