Quite true about enemies, but you used the word, 'enmity' and that isn't correct for animals, or even humans IMO. See the meaning.
There's no anger involved my friend, and that applies to both the preyed and the preyed upon.
In fact the two are working together, albeit perhaps not by choice on the part of the lamb.
There is no anger involved in any of the examples. But if we think on the human level of humans vs. humans, anger can then be a possible motive. eg. a person can lie down with his/her enemy)
Otherwise, not even anger of the cat that torments the mouse to death.
It's likely that the parable on the lion and the lamb lying down together, was invented by someone who didn't understand everything we now know and accept.
Not to suggest that it's not effective for teaching children something. I'll leave it to you to explain what is being taught.
Would the teaching have any effect on deer hunters who kill when their motive is not to eat the animal? (some) ( I did it)