Isn't it more about whether or not you intentionally kill? I think to follow the precept to the extreme, you would have to be a fruitarian. And even then you would accidentally kill some living things.
I think its the kind of topic you could argue about until the cows come home, from whatever trip they've been on.
We must kill to survive, is killing a carrot not as bad as killing a sheep? One has a more sensory existence, that is certain, but does that mean the carrot has less right to life?
All things die, a sheep will die naturally after 12 years, its corpse will feed the worms, bacteria and funghi of the soil. If a man kills the sheep at, say, 1 year - that sheep will feed a maybe dozen people for 2 or 3 days.
So the issue is consciously ending an animals life, rather than letting its life end via unconscious natural processes - the death itself is inevitable and creatures of some form will consume the body.
So the next question is, is death suffering and is causing death for food causing unnecessary harm?
Well, letting a sheep die of old age or disease will surely be a prolonged and more painful death than instantly stunning it and slitting its throat - thus if death is suffering and harmful then conscious, controlled and efficient slaughter is, in a way, the quickest and least painful way to go.
I think the nature of these facts boil down the argument of whether killing for food is ethical or not to a personal conscientious choice.
Can you live with the knowledge that an animal died specifically to be eaten, and then partake in that meat? That decision, I feel, must be a personal choice that has been made after extensive contemplation, not a rule you are to obey.
My personal philosophy is (and I'm sure most other Buddhists would disagree with me on it) that if one does not cling to the idea that life
must exist for as long as possible, and realises that death and killing for food is natural - that so long as an animal is treated well during its life, quickly ending that life to sustain others is in itself not wrong, and will not hinder ones path to enlightenment.
I don't eat a lot of meat at all since I'll only eat meat from free-to-roam, organically raised "happy" animals which is both hard to find and expensive.