Earthlings (available on YouTube), for me, was a game changer. If you do watch it, I will pre-warn you that it's VERY DIFFICULT to watch all the way through due to its violent nature.
Passio is a powerhouse! I've consumed so much of his content over the years, and he has opened my eyes to so many things I was previously unaware of. His understanding of the psychology of order following is unparalleled, in my opinion.
To answer your question about rearing cows for food, if I was given the choice of incarnating into a physical body knowing that I was going to be enslaved by a higher race of beings, I would choose not to. Regardless of how well they may treat me in the days leading up to my death, I could never choose to be someone else's slave knowing that I was pre-destined for slaughter. I would rather not exist.
To gain an appreciation for just how much these creatures value freedom (as we all do), check this out :-)