Mr. Sean Coughlan:

That is correct and there is a reason for that. One component of the reason is genetic.

In the 1980s, a high-profile dairy bull was used extensively in herds that were exposed to TB. If that bull's daughters were in that herd, 95% of his daughters went down with TB. There were daughters of other bulls in those herds and 5% of their daughters went down. It would be ridiculous to say they will not get TB. What we are trying to do is to give another little indicator to tilt the balance in favour of the farmer, so that if his or her animals are exposed to TB, maybe a few less will go down with it.