Muslims/Islam, vegetarian/vegan, peace, love, compassion, mercy ?

Muslims claim Islam is about Peace, love, compassion and mercy, also in our treatment of animals.
I would like everyone who think peace and compassion is important, and still chooses to consume animal foods to consider this:

We all claim to care about animals and to regard them as having at least some moral value. We all claim to agree that it’s wrong to inflict “unnecessary” suffering and death on animals and--whatever disagreement we may have about when animal use is necessary—we all agree that the suffering and death of animals cannot be justified by human pleasure, amusement, or convenience. We condemn Michael Vick for dog fighting precisely because we feel strongly that any pleasure that Vick got from this activity could not possibly justify what he did.

So how can we justify the fact that we kill many billions of land animals and fish every year for food? However “humanely” we treat and kill these animals, the amount of animal suffering we cause is staggering. Yet no one maintains that animal foods are necessary for optimal health. Indeed, mounting empirical evidence points to animal foods being detrimental for human health. But however you evaluate that evidence, there can be no serious doubt that we can have excellent health with a vegan diet. There is also broad consensus that animal agriculture is an ecological disaster. Animal agriculture is responsible for water pollution, air pollution, deforestation, soil erosion, inefficient use of plant protein and water, and all sorts of other environmental harms.

The best justification we have for the unimaginable amount of suffering and death that we impose on animals is that they taste good. We enjoy the taste of animal foods. But how is this any different from Michal Vick claiming that his dog fighting operation was justifiable because he enjoyed watching dogs fight? Vick liked sitting around a pit watching animals fight. We enjoy sitting around the summer barbecue pit roasting the corpses of animals who have had lives and deaths that are as bad, if not worse than, Vick’s dogs. What is the difference between Michael Vick and those of us who eat animal foods?

This book shows that there is no difference, or at least not any difference that matters morally.
Quote from a book that I recommend alot: http://www.eatlikeyoucarebook.com/
And it is very clear that animals do have an interest to live and not to be raised, killed and used by us humans for food: http://bloganders.blogspot.no/2013/07/why-painlessly-killing-animal-for-food.html
So how can you claim that love, peace, compassion and mercy can be combined with killing a sentient being despite the lack of any necessity at all, with an interest to live, who don't want to be slaughtered, exploited and killed by humans?