ecological balance/equilibrium - eg: Animals need to be treated with a humane attitude as they are essential to the ecological balance.;

　　alternative method - eg: Computer stimulation is a great alternative method of animal testing.

　　barbaric - eg: It is, of course, unethical and barbaric to abuse animals.;

　　outlaw-eg: Hunting and sales of leather should be outlawed for protecting animal rights.;

　　brainwash-eg: brainwash sb into believing sty.

　　captivity-eg: The different reasons behind keeping animals in captivity may be education, research, recreation and conservation.;

　　poach-eg: Poaching of wild species for skins, ivory supposed medical purposes should be punished.