2 Nephi 21

2 Nephi 21:6-8 The wolf also shall dwell with the lamb, and the leopard shall lie down with the kid, and the calf and the young lion and fatling together; and a little child shall lead them. And the cow and the bear shall feed; their young ones shall lie down together; and the lion shall eat straw like the ox. The sucking child shall play on the hole of the asp, and the weaned child shall put his hand on the cockatrice's den. They shall not hurt nor destroy in all my holy mountain for the earth shall be full of the knowledge of the Lord. Isaiah is using animals here as an allegory for people, indicated by the preceding verses about judging the poor and the meek. The animals represented are of two classes, the one, by nature, defenseless and the other, predatory and seemingly designed to prey on the first. The theme of judging righteously, in a way that does not inappropriately punish the poor is common throughout the Old Testament, indicating that it was as great a problem 3,000 years ago as it is today, where people who can afford to are not punished by the law to the same degree as those who can not afford to buy their way out.
Can we also understand from these verses that in the millennial day, these types of animals will also literally change their nature and cease to prey on one another? Sickness, death, corruption all entered the world by virtue of the fall, and the world started to bring forth thistles, thorns, briars and noxious weeds instead of fruits and flowers, but how much of that was already there, just not in the Garden of Eden? And if you take away a leopard's deadly grace, what is its purpose? If it doesn't need to run to eat, why would it do so? Would God make a creature so marvelously suited to pursuit and then change it in its paradisiacal state to be mild-mannered? Although, to that point, mankind seems uniquely adapted to violence and we are certainly hoping that will go away when Christ comes.