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ABSTRACT. Scattered SRM residues from BSE-infected cattle are possible to contaminate sewage during the slaughtering process in slaughterhouses. A proportion of the sludge discharged from wastewater treatment facilities at slaughterhouses has historically been processed into fertilizer. We therefore investigated the associated risk of BSE infection to cattle via sludge-derived fertilizer. Each stage of the process associated with BSE exposure was qualitatively evaluated and quantitative evaluations were subsequently performed using infectious dose as a unit of concern. Results of these qualitative evaluations indicated that installation of filter(s) at the drains to the wastewater treatment facilities has been undertaken by many slaughterhouses and has decreased the likelihood of SRM contamination of sewage. The level of sludge-derived fertilizer ingested by cattle was considered to be very low since the fertilizer is mixed with the ground soil, and the amount of soil ingested by cattle is likely to be small. Results from the quantitative analysis indicated the total infectious dose ingested by cattle in Japan from an infected cow has been estimated to be 5.5 × 10 -3 ID 50 . Preventing scattering of SRM during the slaughtering process, installing filters to the drains with the removal of residues from the drain water and preventing the application of sludge-derived fertilizer to pasturelands would be effective to reduce the risk. Although the limited extent of available information, this study should provide useful indication for the development of an inclusive risk assessment for slaughterhouse sludge in the future.

Milk Replacers and Bovine Spongiform Encephalopathy in Calves, Japan

As sources of the BSE infection in Japan, meat-bone-meal contaminated into cattle concentrates at feed plants and replacement milk containing animal fat imported from a BSE affected country are suspected. However, none of them has so far been specified conclusively. Geographical analysis using geographical information system was conducted to examine the possible relationship between the distribution of those suspected feed and birth places of BSE infected cattle in Hokkaido. As a result, there was no clear relationship found, because those feed were widely distributed within Hokkaido. However, the possible geographical linkage was suggested between the birth places and the replacement milk shipped in a specific period. Further investigations will be needed to clarify these possible linkages. Geographical analysis using GIS can assist the detection of risk factors of diseases by visualization of data. GIS becomes effective tools for epidemiological analysis of various diseases like BSE.

Diarrhea of pre-weaning calf seriously affects the management of cattle farms. Awareness and hygienic measures against this diarrhea vary between cattle farming systems, as faming practices vary. To understand these differences, we analyzed results of the nationwide questionnaire survey for diarrhea, which was carried out in the fiscal year of . Analysis was conducted using data of cattle farms, which kept pre-weaning calf at the time of the survey. For comparison, beef farms were classified into three types of farming systems, namely breeding farms, grower and finisher farms, and farms containing all stage of cattle. Dairy farms were also divided into two types by farm size. As a result, all types of beef farms showed relatively higher awareness and took hygienic measures against the diarrhea than dairy farms. On the other hand, farmers' notice to the diarrhea and incidence rates of rotavirus infection and coccidiosis, indicated that pre-weaning calf diarrhea occurred more often in beef farms than dairy farms. From these results, we considered that pre-weaning calf diarrhea caused problems in beef farms than dairy farms. Efficient and effective measures against this disease should be considered according to the type of farming system. Kruskal Wallis p < . Mann-Whitney U Microsoft Excel Microsoft corp. SPSS version SPSS inc.