*sigh* last try then...
Animals are unessesary to humans now. With tech we can outdo and replace any animal on this planet, with tech we could someday cease needing this planet altogether. Therefor, logically, humans should wipe out all animal life, because such life is a possible threat to us through disease, predation, competition for resources, extra. That is the logical solution to all our problems. No animals means no reason to care about earths ecosystem, beyond allowing it to sustain plant life. So now, logically, animals deserve no rights whatsoever, because they are not human.
Was that heartless enough for ya, or do we need to enter the realm of open cruelty (if we haven't already)