I'm currently unconvinced either way on this matter. However, enough arguments have been raised that I think this is worth the time of every reader to think a good deal about.
http://nothingismere.com/2014/11/12/inhuman-altruism-inferential-gap-or-motivational-gap/
Well... the example ran away like this: "If there was a fire and I was given the option of saving just the cow or just the person, I would save the cow". Presumably it would be the same with a pig or a dog.
This is a trasposed version of the trolley situation: 'I would not actively kill any human, but given the choice, I consider a cow to be more valuable'.
The motivating reason was something on the line of "humans are inherently evil, while animals are incapable of evil".