You're not wrong but it's worth considering that life wouldn't exist otherwise. The choices are not kill or let live, the choices are kill or do not breed at all. They breed these animals specifically to kill them.
You're reasoning isn't sound here. Same logic can be applied to other things: breeding dogs to dog fight, breeding humans for organ harvest, etc. And presumably you wouldn't think those justify things.
I would also ask you to consider if you'd like to be born as a creature that will be mutilated, abused and ultimately painfully killed and if you would consider that preferable to never existing.
