I would like to add that there is a reason we banned feeding cattle with animal by-products rather than solely relying on screening slaughtered animals. There are limitations in screening animals. False negatives, especially in young, early stage, asymptomatic cases of disease (they are still transmitting abnormal proteins). Screening every slaughtered individual would be very costly.

You want a combination of preventative measures. But best to break the food chain transmission vector. Cannibals have a circular food chain. That is an issue.