The BVD scheme isn't going that well, in our area at least - it depends on who you talk to.
The problem with Johnes is that the blood test is unreliable. False negatives are bad because you may have an infected cow and not know it, but false positives are worse because if you sign the Health plan you will be told you have to cull the cow AND ITS OFFSPRING! This is a belt and braces approach which may work in a commercial herd (except the infected cow may have already infected a whole lot of others by the time she is identified). However with a rare breed herd you risk destroying an entire precious female family - justifiable perhaps if the test is correct but if it is a false positive, you will have done irreparable damage to your breed.
If you decide to do it and you have rare breed cattle NEVER agree to cull the cow without a faecal test, preferably a culture, and NEVER have the blood tests done within 3-6 months of a TB test as there can be cross reactions.
I really hope the Government doesn't go through with this - at least not yet. Maybe in the future the tests will be better but at the moment it is a minefield.