Earlier quoted context omitted.
If we could genetically engineer animals to be intelligent enough to have conscious desires, and also have an overwhelming desire to be killed and eaten, would it still be morally wrong to eat them? (This dilemma assumes that you share my belief that the demand for meat products causes a net increase in suffering.)
That would be hilarious. Taken to an extreme, we could have those animals be humans that are somehow born masochists, desperate to get consumed by cannibals. Hmm. I think it's morally dubious to make them in the first place. Past that, we're talking about fulfilling their desires. If someone wants to die (say they're suffering from some slow, terminal illness or maybe incurable depression), is it ethical to keep them…
The cow in question repeatedly assures the protagonist that the entire process is very humane and that it desires nothing more than to be eaten and enjoyed by others. It's actually quite offended when Arthur only orders a salad.