ABSTRACT. Since high levels of prions, the causative agent of bovine spongiform encephalopathy (BSE), accumulate in the brain and spinal cord, contamination of beef carcasses with central nervous system tissue (CNST) may occur at post-slaughter process. In this study, we investigated CNST contamination on the surface of beef carcasses using glial fibrillary acidic protein as a marker after splitting and evaluated the effects of washing procedures on contamination removal. High levels of CNST contamination was detected immediately after splitting, especially in the area close to the spinal column. This suggests that spinal cord fragments are attached to carcasses at the time of splitting even though the spinal cords have been removed by vacuum before splitting. Steam cleaning or manually washing with normal pressure water around the spinal column, performed prior to washing with high-pressure water, was found to be effective for reducing the level of CNST contamination. Furthermore, manually washing with high-pressure water could reduce CNST contamination to almost negligible levels. These results are useful for preparation of appropriate sanitation standard operating procedures to reduce the risk of CNST contamination of carcasses for prevention of exposure to BSE prion via the food chain.
ABSTRACT. The tonsils of cattle, including palatine tonsils, pharyngeal tonsils, tubal tonsils and lingual tonsils, are designated as specified risk materials (SRM). However, the detailed distribution of lingual tonsils in cattle is unknown. We therefore histologically examined their distribution in 198 tongue specimens from cattle. The examinations confirmed that the presence of lingual tonsils was limited to the tissue of the lamina propria on the dorsal and lateral aspects of the tongue, not reaching the muscular layer below. More than 90% of the lingual tonsils were located between the distribution center of the vallate papillae and the radix linguae (root of the tongue). However, they were also found in the area extending from the lingual torus to the rostral-most vallate papilla in an individual, suggesting that the complete removal of the lingual tonsils requires elimination of the lamina propria extending from the lingual torus to the radix linguae. KEY WORDS: BSE, cattle, lingual tonsils, specified risk materials (SRM), tongue.
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