New developments in classical microscopy; what can be expected for the official control?

The official control of animal proteins in feed is focused on the prevention of Bovine Spongiform Encephalopathy (mad cow disease). The current legislation of the European Union is planned to avoid the feeding of animal by-products to the same species as its origin (ban of cannibalism, or species-to-species ban). With respect to the official control, the circumscription of the term species in legislation should be defined, and species-specific markers should be available. Markers will include primer sets, antibodies, near-infrared profiles or visual characteristics. The method of classical light microscopy is currently the only accepted method in the framework of the official detection of animal proteins. Besides the necessary development of complementary methods, either as stand alone methods or in combination, the visual characteristics used for a microscopic examination of meat and bone meal particles should be fully explored. Multivariate analysis of a range of characteristics of lacunae in bone fragments revealed that discrimination is possible between mammalian and avian bone fragments. Translation to features for every day practical use should be carried out very carefully, and only comprehensively collected information on a range of features will give a first indication of the source. Characteristics of hairs and feather filaments can be used to identify the origin of animal particles. An in situ identification method has been developed for antibody conjugation with troponin I in muscle fibers on a microscopic slide. A proof of principle is presented. Interlaboratory transferability and validation have still to be achieved. The development and testing of light microscopy markers in the framework of the SAFEED-PAP project revealed that a fine tuning of existing microscopic characteristics appears to be possible. Keywords. Microscopic method, feed, marker, hair, feather, bone, meat and bone meal.