Background: Phytase-based preparations are important feed additives currently authorised in the European Union (EU). The ISO standard 30024 describes a harmonised method for the determination of the phytase activity and is fit-for-purpose for official control of a group of phytase products. However, it is not suitable for the determination of the phytase activity of a new feed additive encoded as 4a16 in the European Union Register of Feed Additives, to wich a slightly different phytase activity definition has been attributed. Objective: To establish a robust conversion factor to support official control laboratories that apply the ISO method when monitoring feed products containing the 4a16. Methods: The phytase activity of test materials was determined by the participants by using the ISO and/or the 'applicant' methods. Results: Robust standard deviations for repeatability and for reproducibility of the methods applied for the determination of the phytase activity in the materials containing the 4a16 feed additive ranged from 2.4 % to 17 % (ISO method) and from 7.7 % to 39 % ('applicant' method). Conclusions: The data obtained confirmed the performance characteristics published for other phytase-based feeds in the related standard methods. These results allowed to estimate a factor of 2.68 to convert phytase activities measured with the ISO method into the enzyme activity measured with the 'applicant' method. Highlights: The obtained conversion factor will allow EU official laboratories to screen feed samples supplemented with the 4a16 phytase by applying the ISO standard 30024.

GONZALEZ DE LA HUEBRA Maria Jose;  ROBOUCH Piotr;  EMTEBORG Hakan;  BELLORINI Stefano;  CIZEK-STROH Aneta;  VON HOLST Christoph; 

2019-12-06

AOAC INT

JRC116314

1060-3271 (online),   

https://publications.jrc.ec.europa.eu/repository/handle/JRC116314,   

10.5740/jaoacint.19-0107 (online),