Maybe you may think it obvious that you hurt animals by eating meat, but you still think you are justified in doing so. Or maybe you don't think such harm is justified, and so are a vegetarian. But I want to argue that, all things considered, you are not hurting animals; you are helping them.
First, notice that the cow or pig that once was the meat in front of you is already dead. So you can't hurt that animal much, except perhaps by violating its last wishes. But what about other cows and pigs? Doesn't buying more meat increase the overall demand for meat, and won't farms out there respond to this increased demand by killing more animals to send to grocery stores? So aren't you responsible for the killing of those animals?
Well not really. Farmers are going to kill pretty much all their grown animals no matter what the demand; they really don't have much else to do with the animals they raise for meat. But farmers will respond to changes in demand by changing the number of new animals they raise to kill later. So by buying more meat from the grocery store, you are responsible for more deaths of future farm animals.
But the alternative to those future animal lives cut short by butchery is not longer future animal lives. The alternative is that those animals will never have existed. People who buy less meat don't really spend less money on food overall, they mainly just spend more money on other non-meat food. This results in fewer pig farms and more asparagus farms, and pretty much the same overall amount of land devoted to farming. Creating more asparagus farms does not create more wilderness where wild animals can range free; this is not what asparagus farms do. So the real choice here is between creating pigs who live for a while and then are killed, and creating more asparagus plants.
If asparagus plants have little moral worth per se, our question then comes down to this: is it good or bad to create pigs who live for a while and then die? Well, is it good to create people that will eventually die? We usually say yes, if their lives are "worth living" overall. That is, if they get value out of being alive, and are not in a situation like severe torture, where they would rather be dead than alive. So are pigs lives worth living?
We might well agree that wild pigs have lives more worth living, per day at least, just as humans may be happier in the wild instead of fighting traffic to work in a cubical all day. But even these human lives are worth living, and it is my judgment that most farm animal's lives are worth living too. Most farm animals prefer living to dying; they do not want to commit suicide.
If so, the consequence to others of buying that meat in the grocery store, rather than asparagus, is good; you create farm animals whose lives are worth living. And thus the consequence of buying asparagus rather than meat is, by comparison, bad. So if you, like me, think your actions are more moral when you do more good for others, you should agree with me that meat is moral, and veggies are immoral.
There are two standard responses to the argument I've just given. The first response says that killing is just wrong, even when the consequences to others of doing so are good. The second response claims that in fact most farm animals live as if in torture, and so the animals would rather be dead than alive. By this account I guess killing existing farm animals is a kind merciful act, while creating new farm animals is cruel. If you have doubts on this point, I suggest you visit a farm.
Now it might make sense to be picky about how the farm animals that you eat were raised. It would be kind of you to pay a little more for your meat to improve the lives of the animals that become your meat. Just don't confuse a lack of extra kindness with cruelty; people already do more good by buying ordinary meat than by buying veggies.
How kind would it be to animals to spend more or less of your income on food? Changing your food budget might change the amount of land that is farmed, though this effect is weak because farmland can be used to produce non-food products. Corn, for example, may be used to produce ethanol. And if you do manage to induce less farmland and more wild land, you'll have to realize that, per land area, farms are more efficient at producing "higher" animals like pigs and cows. So there is a tradeoff between producing more farm animals with worse lives, or fewer wild animals with better lives, if in fact wild animals live better lives.