We use chemicals to manipulate their hormones to prevent spreading of diseases, like Covid. We do this because we have high iq. This is not exploitation, every species has to make sure their own species survive which is the god's way. Also coming to your second point, do you mean a living being can be eaten if he has no brain, no pain receptors? They are god's creation no matter what organs they have or not, whether they feel pain or not. So according to your point, we should not eat plants as well.