There are objections one can make if Christians insist that humans can eat animals because God has made the animals for us to eat, or that the purpose of animals is human use. These are objections that either come from within Christian thought, can fit into Christian thought, or do not contradict Christian thought.
According to the Book of Genesis, in God's perfect plan for creation, humans did not eat animals.At the creation of the world in the book of Genesis, God gives man dominion over the earth and all the animals. He says in 1:26 "let them have dominion over the fish of the sea, and over the birds of the air, and over the cattle, and over all the earth, and over every creeping thing that creeps upon the earth" and in 1:28 "have dominion over the fish of the sea and over the birds of the air and over every living thing that moves upon the earth."
Interestingly, in 1:29, God says "Behold, I have given you every plant yielding seed which is upon the face of the earth, and every tree with seed in its fruit; you shall have them for food." Even after giving man "dominion" over the animals, God specifies that man can have the plants for food. The text repeats the point. Again in 2:9, "And out of the ground the Lord God made to grow every tree that is pleasant to the sight and good for food..." And then before prohibiting man from eating from one particular tree, God says in 2:16, "You may freely eat of every tree of the garden." Again, God explicitly tells people they can eat the plants He created, but there is no explicit mention of whether the animals are available for food.
So before the Fall, there is no mention that people eat animals. I find this absense striking. God commanded man to have dominion over the animals, AND God explicitly commanded man to eat plants. With such explicit mention of dominion over animals AND explicit mention of what people are supposed to eat, it seems like a loud silence on animal consumption. It would seem perfectly within context to mention eating animals at this spot, but it doesn't happen.
It seems that the permission to eat meat was a later accommodation for sinful humans. This all makes theological sense, too: it was humanity's sin that tainted creation and brought death into the world.
And the fact that according to Genesis, God made the animals first suggests that they have his special concern and consideration. It is not that God made humans and then gave them food: they existed for some purpose other than the benefit of humans when they were first made.
So did God create animals for the purpose of humans to eat them? In the perfect plan for creation, God didn't tell people they could or should eat animals, and in fact the text makes explicit that plants are meant for human consumption.
Simpler: what is an animal made for?
What did God create animals for? I don't know. But I think it is hard to argue that God, say, made a chicken so that it could have its beak cut off and spend its entire life in an extremely small cage. There are all sorts of ways that humans have manipulated and limited animals in ways that run contrary to any biological understanding of what the animal was designed for.
Even if at a fundamental level, a Christian understanding of animals is that they are ours to use, that would not justify the extreme cruelty and suffering of current animal agriculture.