We should treat others as we want to be treated ourselves
All animals are conscious and they do value life as much as we do.
If we don't want to be killed, we shouldn't kill other animals (regardless of species - humans, dogs, cats, cows, chicken, etc.).
If we don't want someone else to steal our family, we shouldn't steal their family.
If we want to find our purpose in this world, we shouldn't steal others purpose.
If we don't want to be exploited and abused, we shouldn't abuse anyone else.
If we don't want to become enslaved, we shouldn't keep anyone else as a slave.
If we don't want to hurt any animals, we must become vegans (i.e. stop eating, wearing and using animal products, and in other ways do actions that are hurting and killing animals).
If we love animals, we don't kill animals. We don't kill and eat anyone that we love. If we love animals, we must support their want to not be oppressed, including not to be killed.
I recommend this lecture: http://www.youtube.com/watch?v=oLgGnP0pWzM
All kind of animal products, including eggs and milk, are causing humans and other animals terrible suffering, oppression, starvation and death. Being vegan is the only way not to participate in the oppression.