Innovative methods for the determination of the taxonomic origin of processed animal proteins in feed.

The use of animal by-products in feed depends on their nature defined by the type of tissue or body parts and the species of origin. Currently, the detection of unauthorised processed animal proteins (PAPs) is based on light microscopy and PCR methods. Light microscopy identifies structures on the basis of their morphology and enables identification of particles (such as bones, cartilages, muscle fibres,…) while PCR is able to detect and identify the presence of specific animal DNA in feed. Nevertheless, for some scenarios, even combined, these methods do not succeed in determining the taxonomic origin of the PAPs. A typical example is that of an aquafeed containing authorised porcine PAP together with dairy products: the analysis will conclude of the potential presence of ruminant PAP.
Therefore, there is a need for developing methods allowing a taxonomic characterisation of visual structures such as bones fragments and muscle fibres. For the characterisation of bones, NIRM has yet demonstrated its potential. However the limitation of NIRM is when the presence of bones is reduced or absent. This study investigated the potential of NIRM for the determination of the taxonomic origin of muscle fibres.
The NIRM was experimented on 2 porcine PAPs vs. 6 ruminant PAPs and 7 fishmeals all of industrial origin. Results showed that NIRM allows differentiating muscle fibres from different taxonomic origins: fish, ruminant and pig. In addition to this taxonomic classification, results also reveal differences inside taxonomic clusters of PAPs (e.g among different ruminant PAPs and porcine PAPs).
The results obtained on this type of meals are promising and offer new perspectives. Tests on adulterated feeds need to be performed by NIRM prior to validation.