When we observe the animal world, it appears that there is a great degree of meanness and viciousness. A predator tears and mutilates its prey. How can a compassionate G‑d sanction this? And if it is nevertheless acceptable to G‑d, why is this behavior not condoned in mankind. Contrarily, if G‑d demands compassion within human interactions, why did He not create the animal kingdom accordingly?
Your question assumes that terminating life is mean and vicious in all instances. But this is not so. G‑d, in His infinite wisdom, imparts life and terminates life. It is G‑d’s will that living things not live forever. But while alive, they thrive on life. Therefore, the food chain, which is such an integral, vital process of the world, subsists on one organism sustaining its life via the life of another.
Accordingly, living things preserve their lives by consuming others not as a moral decision, nor even out of a conscious decision to terminate life. They simply act upon divinely-designed instinct to eat. In this respect, a lion’s feeding on its prey is no more “mean and vicious” than a grazing cow’s tearing away and cutting up living grass in its jaws. Actually, the lion is less vicious than humans insofar as it will never kill indiscriminately and only kills for food what it needs in order to survive.
Thus, it is we, as humans, with free will and an innate sense of morality, who incorrectly transpose our sensibilities to the behavior of the animals, and thus perceive the lion as vicious and the cow as peaceful. But while an animal’s decision to take life is instinctual and not moral (i.e., not mean and vicious), our free will and moral potential makes our decision to eat, or how to interact with our surroundings, not only instinctual but also moral. Since humans can choose to kill, G‑d imposes moral judgments, restrictions, and punishments on killing, in order to ensure that it will be justified by G‑d and therefore not mean and vicious.
Regarding killing for food, G‑d initially designed that man should not subsist by killing animals, but rather that he sustain his life through consuming the life force of vegetation. This is not necessarily because taking the lives of animals is more “vicious” than doing so to plants, but because plants are a lower life form and preserving the life of animals shows a greater respect for life.
However, even if it is because eating plants is more merciful, as we see is a major reason behind many of the laws governing eating animals such as not eating from the animal while alive, taking its life with a minimum of pain, eating only herbivores and not carnivores, etc. that’s only because G‑d wants to sensitize us to making the right choices about killing in order to preserve life. But animals’ lack of free will and resultant divinely-instilled instinct removes any element of meanness or viciousness and thereby precludes the need for any moral judgment or restrictions on what, when, and how much animals kill to eat since they do so only according to G‑d’s will and plan for Creation.
As such, the prophecy of Isaiah (11:6), “And a wolf shall live with a lamb, and a leopard shall lie with a kid, and a calf and a lion cub and a fatling shall lie together, and a small child shall lead them,” is not necessarily to be understood literally that carnivores will change their diet. Rather, the verse is a metaphor regarding the End of Days conveying the idea that the strong will no longer harm, exploit, and kill the weak, but rather all individuals, peoples and nations, large or small, powerful or feeble, rich or poor, will follow the lead of the Jewish People, the child of G‑d, to serve Him in peaceful unison and harmony.