There's no reason to believe that single cells can't be conscious too.
You'd have to eat organic molecule synthesized through a non-biological, industrial process that feeds on energy harvested in space, so that all solar energy on earth can be given back to the wilderness.
Yes, using terrestrial solar and wind energy deprives geologic, atmospheric, marine and wild biological processes from the energy they're naturally due, and it is not ethical to use it anymore than it is to eat animal flesh.
More seriously, we're dissipative structures, and we can't survive (i.e. keep our inner entropy low) without raising the entropy in our surrounding. So there's gonna be some environmental disruption if we want to survive, and it's going to be at the expense of other organisms, be they cute, plain or disgusting.
Edit: with all that said, I think our current meat consumption rate is suicidal for environmental reasons. I do think we should limit the amount of meat we eat, but not out of compassion for non-human animals. I may have another opinion if I didn't have kids, but since they're there I'd rather limit as much as possible the cataclysm that's unfolding before our very eyes.