The following quote is from George Monbiot's most recent Guardian column. It's worth reading in full, but for now:
[W]hile researching my book Feral, I came to see that our perception of free-range meat has also been sanitised. The hills of Britain have been sheepwrecked – stripped of their vegetation, emptied of wildlife, shorn of their capacity to hold water and carbon – all in the cause of minuscule productivity. It is hard to think of any other industry, except scallop dredging, with a higher ratio of destruction to production. As wasteful and destructive as feeding grain to livestock is, ranching could be even worse. Meat is bad news, in almost all circumstances.
That's good stuff. He continues:
So why don't we stop? Because we don't know the facts, and because we find it difficult even if we do. A survey by the US Humane Research Council discovered that only two percent of Americans are vegetarians or vegans, and more than half give up within a year. Eventually, 84 percent lapse. One of the main reasons, the survey found, is that people want to fit in. We might know it's wrong, but we block our ears and carry on.