Abstract Due to the actuality of spongiform encephalopathies and their proven spreading by means of animal feed containing meat and bone meal, the description and measurement of osteocytic lacunae contributes to more easily distinguish bone fragments in meat and bone meal. Transmissible spongiform encephalopathies (TSEs) have attracted a lot of attention, especially after 1986, when the first case of BSE (bovine spongiform encephalopathy) was detected. Since the outbreak of spongiform encephalopathy (BSE), the use of animal protein including bone meal as an ingredient in animal feed has been controlled by several regulations including Regulation (EC) 999/2001, Regulation (EC) 1774/2002, and Regulation (EC) 1234/2003. The classical microscopic method is the only official method for detecting animal protein in animal feed in the European Union (Commission Regulation (EC) 152/2009). By applying the microscopic method to the animal feed samples, we performed detection in order to determine the presence of animal proteins that originate from mammals and fish. The microscopic analysis of all 421 samples, of which 115 were raw materials for the production of animal feed, 230 were concentrates for ruminant nutrition and 76 were concentrates for non-ruminant nutrition (32 concentrates for laying hens and 44 concentrates for pigs), did not provide positive results, that is, no remains of animal tissues of mammalian origin were found in any specimen. Whereas in 10 out of 32 (31.25%) concentrates intended for non-ruminant nutrition (laying hens), pieces of fish tissue were found. In these samples, we usually detected the presence of fish bones, gills and scales.
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