The overwhelming majority of these animals have spent their entire lives confined inside sheds, never going outdoors for a single hour. Their suffering isn’t just for a few hours or days, but for all their lives.
Factory farms breed diseases which are resistant to medicine and can affect humans, posing a substantial health risk. A super virus that originates from the food supply has a large chance of driving human extinction.
Domesticated animals need to be heavily inoculated to meet consumer demands.
The fact that humans (in modern societies) can now have a healthy and fulfilling diet without the need to kill animals for their protein, makes it immoral to continue killing sentient beings just for their taste. If we can avoid killing it is our moral duty to do so.
This argument appeals to the belief that any living creature(animal) is sentient while sentience itself is a heavily debated subject to which there never will be an answer(due to it's subjective nature)
They are moral in my moral framework, because in it, 'me getting a lot less expensive meat' is a supreme cause to 'animal well being'. I still consider 'animal well being' a good cause, just subordinate.
If both causes can be consolidated, then it is immoral to support clinging to factory farms.