Can Lions and Tigers survive on a diet that does not include animal protein?

In my unending quest to determine the truth about whether humans were designed by God to "require" animal protein to live I ask this question. Can Lions, Tigers, Bears, or Alligators live(in good health) on a diet that does NOT include animal protein?

Can Lions and Tigers survive on a diet that does not include animal protein?
As for the bear, that's questionable since bears are, like humans, omnivores. Strict carnivores, especially cats like lions and tigers have a very short digestive tract which is incapable of digesting protiens and nutrients from vegetable matter. Same with alligators. Cats, and dogs, often eat grass, but they do that as a sort of digestive aid since the grass helps them go poop because it cannot be digested. Not kidding. I worked at a big cat rescue for 7 years and picked up a huge ammount of lion and tiger poop, and grass came out looking exactly the same as when it went in. The wild lions and tigers ingest a tiny ammount of vegetable protein by eating the contents of their preys stomachs. Carnivores have to eat meat and cannot survive on a vegetarian or vegan diet. As far as your ethical question, I can only provide my own personal opinion. Since our bodies are capable of digesting meat and we can get ill if we do not maintain enough protein and the only way to survive on vegetarian or vegan diets is with supplements that Adam and Eve certainly couldn't find (as there were no health food stores in the garden of Eden) I think that humans were designed to be omnivores and eat both plants and animals.
Reply:Yes, but you should pardon the expression, its' a bear. Balancing vegetable proteins in sufficient quantities and proportions to maintain their health would require serious research. Not all protiens are equal.