i don't think your connection of animals rights with relating a lion to a sheep in the food cycle is a very sound arguement. lions, for whatever reason, don't seem to take anymore from the lamb than what is needed for thier survival.
we on the other hand, who can understand the difference between neccessary and unessecary evil are the ones causing the debate.
we interpet the suffering of the animals in question as such, and we choose to inflict pain on them anyway.
everyone knows this is wrong, but there are some heartless bastards that don't care.
so you have some issues with the word "right", and can't quite grasp the meaning or origin of the word. that's okay. if you just imagine that the experiment being conducted on a colony of mice is instead being performed under the exact same conditions on a group of actuall humans, i think you will understand that the procedure is unpleasent for them, and that we should not continue to do it, unless the people want to go through with it.
None.