"So how does a badger pass TB to a cow ?"
Everyone here is talking about 'bad science' but nobody is actually describing WHY it is 'bad science'.
Someone has asked the question, and so I will answer it:
It is clearly known how this vector works. How many of you live in the countryside and know what badger shit consists of? Badgers are omnivores: therefore, their dung is remarkably similar to ours (more fibre though). Badgers make areas called 'latrines' and you will find a an area where they have dug holes and filled them.
So: what happens, is that the badgers will either visit the dairy yard because of the spilled grain fed to the cows, and sh t there, or the cows will graze the grass around the badger latrines. Either way, the cows ingest the badger sh t and become infected. Because they live in close proximity to eachother in a humid environment (cow shed), and they are already stressed by intensive lactating, they pass it on to eachother.
I do support badger culls. Not because I hate badgers or support TB cows or any other such thing. I have never ever done anything to hurt a badger. None of this is the point, in my opinion.
I support a cull because we humans have interfered so badly in the ecosystem that it is all out of balance. Badgers are at the top of the food chain (apex predators), and have been protected for years. There are simply too many of them. The impact this overpopulation has on the rest of wildlife, can no longer be ignored. Badgers have a tremendous sense of smell, and eat anything. Their over large numbers are now hurting other less sexy/cute/cuddly/fashionable species and sending them to extinction: nightingales, hedgehogs (a favourite snack), bumblebees (which nest in mouseholes, a nice little morsel of grubs and honey), ground nesting birds. I have not heard a nightingale for over 15 years, and it dawned on me the other day I haven't seen a hedgehog for some time either. We are overrun with badgers in our area (secret, and no I have never hurt them. I just observe with my eyes).
Sentimentality is not good for nature and we humans have put it out of balance. We must respect all of it, live in balance and not impose our misty eyed views on it.