Target cattle age of post-slaughter testing for bovine spongiform encephalopathy and infectivity entering the human food chain in Japan

A model of possible outcomes of bovine spongiform encephalopathy (BSE)-infected cattle in Japan was constructed, and the expected proportion of BSE-infected cattle entering the human food chain and the expected infectivity remaining in edible meat per capita by breed variety and sex were calculated, while changing target ages of BSE testing. As widely accepted, BSE testing for all ages could reduce the proportion of infected cattle entering the human food chain and their infectivity. It was especially effective among female dairy cattle, but the resulting reduction was quite limited. The effectiveness of BSE testing on food safety hardly differs between the target age of ⩾21 months and all ages.