@Ox I would disagree on that. While I do believe that we've perhaps gone a bit overboard on meat production and consumption the truth is we evolved to eat at least some animal protean. The ability to completely cut meat out of the diet is a very modern invention- and I mean less than 100 years style modern.
Only the global market, with it's ability to draw produce from many different growing regions allows the nutritional balance required to eat healthfully. And, that's really only in countries where such a global economy has really taken route. Even then, there are areas that are less developed and require more local agriculture to feed their people.
Eating healthfully within that global market can also be quite expensive- far more than some of the less fortunate within even first world nations can afford.
There is truth, however, in how we treat animals being a reflection of our humanity. This should absolutely extend to how we treat and raise livestock. There should be no suffering for those we will be eating and when it comes time to slaughter the animal it should be done in the most humane, painless, and quick way possible.