Abstract. In 1999, the European Union (EU) approved 3 rapid methods for the testing of bovine brain samples for the presence of bovine spongiform encephalopathy (BSE). The evaluation that led to the approval did not include an analysis of autolyzed material. Member states of the EU have active surveillance programs for BSE, which target fallen stock as well as other categories of cattle. Autolysis is a common feature of fallen stock samples because there can be a considerable delay between death and collection of samples. Therefore, it is important to know whether these tests perform optimally on autolyzed samples. The Veterinary Laboratories Agency (VLA) selected 250 positive fallen stock samples. These had been detected during routine testing using the Prionics-Check Western blot and confirmed as BSE cases by immunohistochemistry or electron microscopy. Samples were graded according to the degree of autolysis and then tested by the 3 methods: PrionicsCheck Western blot, Platelia test, and Enfer test. All 3 methods correctly classified the samples as positive BSE cases, therefore alleviating doubt about their ability to do so. Subsequent EU validation exercises, such as those conducted in [2002][2003], have included the testing of autolyzed material. It is important that all new methods be evaluated on autolyzed tissue before approval for official use.
A method for the separation of 17 different polynuclear aromatic hydrocarbons (PAHs) has been developed. After separation by thin-layer chromatography, the PAHs are examined by high-performance liquid chromatography using ODS and PPS stationary phases. The elution times of all 17 compounds relative to benzo[a]pyrene have been computed. Six representative compounds have been added to bierwurst and to water to check recovery values. Work on stubble smoke has been confined to benzo[a]pyrene only.The method of extraction and clean-up varies with the substrate but the method of determination of the P A H compounds in the final extract is the same in all three cases. Confirmation of identity is obtained by measuring the peak-height ratios for each P A H a t two different excitation and emission wavelength combinations. The limit of detection of benzo[a]pyrene is 0.02 pg kg-1 in food, 0.3 ng 1-1 in water and 150pg per filter in smoke.Recoveries of the six representative compounds are generally in the range 75-100% a t levels approaching the limit of detection.
The stability of several medicinal additives in cattle, pig and poultry feeds has been monitored. The feeds were stored at various temperatures under different conditions; processes such as freeze-drying, gamma-irradiation and pelletization were also applied. The medicinal additives appeared to be more stable in the feeds stored at reduced temperatures and under conditions that totally exclude light. Processing of feeds and storage at elevated temperature appeared to reduce the content of the medicinal additives examined.
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