@Spinoza
And if the humans were given free reign to live their lives as they wish, not being deprived of anything they require, up until a certain point when they are given a pain-free death. What if they were even raised in such a manner that they were taught their purpose was to fulfil some end that their parents/masters want of them, and consequently they enjoy fulfilling it...
It's a remote possibility, and involves coercion all the way. Besides that, I'm not sure that there is a human that is so psychologically sub-par that they would be indifferent to such a thing. Such a life would be one of confinement and regulation, and I suspect few humans would have no inclination to resist it. Therefore, it cannot be said that it doesn't result in the suffering of the individuals concerned and so, it may as such be held to remain morally impermissible.
But maybe you think that's not an entirely decisive response on my part. Maybe it's not, but on the subject of moral questions, things are frequently indecisive. We just have to appeal to the best arguments, not necessarily the absolutely conclusive ones. I believe that what I wrote above does constitute, at least in part, an adequate response to your hypothetical.
(though it does remind me of stories of children willingly being sacrificed)
Where and when did this happen?
I guess I'm just uneasy with the whole idea of forcibly using a sentient being as a means to an end
I'd say also that the element of coercion in raising cattle is far less than what it would be in rearing humans for the same purpose. If a human were placed in such a situation then they would definitely need to be forced to do certain things, to adopt a certain way of living, to allow their captors to shape their way of life entirely. In the case of livestock, the use of force is comparatively minimal, and the animals are essentially living the same life they would in the wild, free of external influence.
Slightly off topic but...if there is high demand for artificial meat, how long would it take to produce something as tasty as chicken wings?
Sorry, I'm not really knowledgeable on the subject of artificial meat. Not being a vegetarian, I prefer the real thing.

Even so though, I suppose such substitutes would be useful, especially for getting people off of eating meat. It would be much easier to do if people didn't have to go from eating real food to rabbit food. And I think people simply will have to start eating less of it anyway, due to the environmental impact of rearing cattle, in addition to the often objectionable practices involved with raising livestock.
Just to clarify, I'm not opposed to vegetarianism, and I think people should start moving towards being vegetarians ultimately, given that meat consumption isn't really necessary and it's also arguably becoming increasingly unsustainable. I myself don't even eat meat as much nowadays, and I certainly don't feel the need to. Even so, I think that the option to eat the stuff should be retained. I'm not for forcing people to stop, but I think we could do well to eat less of it.