Microscopic method in processed animal proteins identification in feed: applications of image analysis

Following the outbreak of BSE, processed animal proteins (PAP) were banned in animal feedstuffs in the EU and each individual member state was required to implement a feed quality programme to enforce this ban. An essential aspect of these programmes was the adoption of EU-approved methods for detecting PAP in feed. The official analytical method for the detection of processed animal proteins in feedstuffs is the microscopic examination technique described in Commission Directive 98/88/EC. At the present, however, a simple PAP detection in feedstuff is not enough, and an improvement of the microscopic method is required (Gizzi et al., 2003; Moretti et al., 2003; Pinotti et al., 2003). PAP differentiation, not only between classes of vertebrates, but also at higher taxonomy levels, in fact, has become mandatory with Regulation 2002/1774/EC. This Regulation does not relax the total ban on feeding PAPto ruminant species, but for other livestock simply prohibits the use of feed containing processed proteins from the same species (prohibition of cannibalism). Therefore, while the microscopic method may be adequate for enforcing the EU’s total ban on MBM in ruminant feeds, and it is usually able to distinguish fish from land animal material, it is often unable to distinguish between land (terrestrial) animals (i.e. poultry and mammals). Origin of animal material in feed is based on the observation of bone fragments and their morphological features. Thus, although it is usually possible to identify the animal class from bone fragments characteristics, several of these features in land animals materials (i.e. poultry and mammals) are not always distinguishable. Starting from these assumptions the aim of this study was to evaluate the potential application of image analysis for distinguish among land animals in PA P identification and characterization.