Just imagine how a lettuce feels when it is beheaded. People say plants don't feel pain but how do we really know? Perhaps in making that salad you inflicted horrible pain on a whole lot of living creatures. I worry about this and hence keep my fruit and vegetable intake to a sensible level.
I like to eat meat because it helps ensure the survival of stupid species. Sheep would be extinct were it not for the fact they are extremely tasty. All they know how to do is eat grass and follow one another. We've been helping them do these activities for over 2000 years (I didn't learn much in Sunday school but I know some of the stories involved shepherds). We keep the predators away and provide lush pastures so they can just happily much all day without having to deal with that whole survival situation. Aren't we nice?
Chickens are similar. They are slow birds that fly very poorly, yet taste very good. They'd be long gone without us.
If we really want to save the pandas we should start eating them. If pandas tasted better than lamb New Zealand would start growing bamboo in place of all that grass and we would have a sizeable panda population very quickly. It makes sense.