What's your definition of "consent"? For example, if you own a dog, you generally have no problems seeing what your dog agrees to do (="consents") and what it doesn't.

It has to have some idea of what's going on. A dog is operating entirely on instinct. Humans still use a lot of instinct, but that's hardly a reason for one human to make a decision for another.

True, but it seems to me the intervention bar is much higher in this case.

Why?

If you have some a priori reason to believe that a life is worth living, then it would take a lot of evidence to prove otherwise. If the opportunity cost of not living a life worth living is substantially higher than the direct cost of a life not worth living, caution would be appropriate. But these don't seem to apply.

If you're not certain, it's easier to reverse a choice of life than a choice of death. That applies to the wild, but I don't think it's likely we'll find reason to believe that factory farmed animals' lives really are worth living any time soon.

If you just consider action generally more dangerous than inaction, that would apply for destroying wildlife, but factory farming is action. Avoiding it is inaction. It's a point against factory farming.