Things I reckon
Jeff Robinson and I would agree on:
Lots of animals other than humans are sentient, have a point of view, a mind, emotions, emotional attachment, the capacity to feel pleasure and pain. How wide this sentience spreads is a tricky question: sheep, certainly; snakes, probably; frogs, possibly; nematode worms, probably not. Also, it is probably possible for a form of awareness to be present without a unified sense of self: this may well be the case with frogs. This isn't well understood, but the important point here would be that we both agree that the majority of farm animals are sentient beings capable of suffering.
We also agree that sometimes there is a need for us to kill other sentient beings, and I can add here that I don't approve of the idea of killing other animals without a good reason to do so (hence dealing with ddraig's pet-bashing objection). But this takes us to the sticking point: what constitutes a good reason?
I'm conflicted over animal experimentation, which involves not merely killing animals but also intentionally inflicting suffering on them. Both of my siblings would be long dead without a treatment developed by testing on sentient animals. In some ways, I can see using animals for testing as more justifiable than using them for meat.
Over meat and dairy, I'm less conflicted in the sense that I do see 'for food' as a decent reason for killing animals. Here we meet a point of sharp disagreement. I acknowledge the suffering that modern farming causes, and would like to see it reformed, but I don't in principle have a problem with keeping animals for food if the animals are kept well during their lives, something that I probably see as more possible to do than Jeff does.
While I agree with Jeff over the horrific nature of many slaughter practices, I don't have a sticking point with the actual act of killing per se: in theory at least, a bolt to the brain should knock out consciousness before the brain has even had the time to experience any suffering. This particular animal is only alive in the first place because it is going to be killed. I can see how that may sound harsh. I'm not demanding that others agree.
I don't expect to change opinions here, but we can reach a point where we understand each other's position at least, where we are not simply talking past one another.