Animals all over the planet kill each other for food. It's part of life. Farm animals are not people and never will be. It's silly to think they deserve the rights of people or to be on the same moral high grounds as people.
When we harm or show an incorrect appreciation for other sentient beings, it shows not only disrespect and lack of understanding and compassion, but it diminishes human dignity.
[1] http://m.livescience.com/22178-parrots-reason-three-year-old...
[2] http://www.cosmosmagazine.com/news/researchers-say-mice-feel...
[3] http://www.popsci.com/science/article/2010-07/squint-if-it-h...
[4] http://www.tor.com/blogs/2013/06/when-doves-cry-scientific-a...
[5] http://news.discovery.com/animals/birds-hold-avian-funerals-...
Agreed. But the least you can (and should) do is spare them the suffering and kill them instantly.
Animals deserve, at the very least, the right to not be put through unnecessary suffering.
They're not people, that's correct. Humans are the highly evolved species of the planet. In fact, we're so evolved that we've come to realize that taking pleasure in others' pain (animals included), just like the lack of ability to feel remorse or empathy, are potential indicators of serious mental illness (http://en.wikipedia.org/wiki/Dark_triad).
It's precisely because we're more advanced that we should show some humanity (I think this is a common sense definition) and not harm sentient beings without a clear need to do so.
Or we can just treat anything and everything like expendable resources. Sounds a tad inhuman to me.