and the fine young woman who raised it, the woman having won a prize for her efforts bringing up the cow. Beside her is the a stack of barrels of oil that went into raising the cow. ("The End of Cheap Oil," National Geographic June 2004, the picture of the girl, the cow, and the six barrels of oil is on pages 98-99.) It is immediately evident that the mass of oil consumed in raising the cow is pretty much equal to the mass of the cow itself. Thus, it is doubtful, given that much of the cow will end up on backyard grills and in Big Macs and Whoppers, that making biodiesel out of cows is a rather expensive way of making fuel and certainly is a net energy loser.
The United States consumes 155,000,000 barrels of oil each year to grow cattle.
http://www.harpers.org/Oil.html This means that 2% of our total oil consumption (7.1 billion barrels in 2002) goes to raising cattle. I'm quite sure that the situation is not appreciably different in Europe. It's very nice that you can recover a small fraction of the energy cost of a cow by making some of the destructive and noxious waste of the whole wasteful enterprise into biodiesel, but as an energy solution, this has all the dubious features of other perpetual motion machines: It sounds good to the credulous, but it's otherwise useless.
I think a better way to avoid the spread of BSE or CJD would simply be not raising the cow, killing it and eating it in the first place.