https://www.dominionmovement.com/watch
Watch any consecutive 10 minutes of that, and let me know if that seems like it doesn't hurt animals. The evidence that industrial scale animal farming is harmful to animals is overwhelming. There should really be no debate about that fact at this point.
There is an incentive to raise them quick, raise them huge, and move them along the whole process as quickly as possible. Those things are generally not conducive with providing a humane life for them.
I agree the ideal killing is instantaneous, but the killing moment is not the only source of pain, and the ideal killing may not be very common. Sometimes we can't even kill humans quickly and painlessly, for example with the several botched lethal injections that took place a few years ago.
