Give Me A Break,
with all do respect,
if you are not allowed to kill animals you shouldnt be allowed to even if you are kind to them (or even save there lives.)
If you can it shouldnt make a diffrence if you are cruel to them if you are allowed to eat the meat unless clearly specified otherwise by the torah (such as by schita), of course there is a seperate issur to be cruel to animals, but to say the torah made the laws of schita and then commanded us to bring animals as korbonos ,very cleary states that it is okay for pepole to eat meat and then chazal proceed to tell us that we should eat meat on shabbos and yom tov but only means all that in a case were the animals owe you there lives seems to be a bit of a stretch,
besides for the point that were do you get the idea that saving somthings life should be a reason you can kill it?