Markers for microscopic detection

A range of markers can be used to detect or to identify animal proteins in animal feed. The presence of hairs and teeth, of feather fi laments, and of scales, gills and otoliths will point to the presence of material of the vertebrate classes of mammals and birds, and to the superclass of fi sh, respectively. The structure of bone fragments of different groups of the class of ray-fi nned fi sh is clearly distinguishable, and an identifi cation on the level of ray-fi nned fi sh orders can be achieved. The difference between mammalian and avian bone fragments is more complicated. The collection of information on a range of markers of bone fragments might give a fi rst indication of the source of the material. It is important to synthesize all available information; the application of a single marker, especially used for discriminating between mammalian and avian material should be discouraged. The use of programs such ARIES allows to interpret the collected information in a reliable way. A range of confusing particles in a feed complicates the correct detection and identifi cation. This range includes material of invertebrate animals, minerals, plant hairs and certain plant structures (seed epidermis).