Please help me choose the right career?

Well it sounds like a degree in Animal Sciences would put you in the right direction. To do the work you want to do though will require higher degrees. To work with large animals you probably will want to intern at a zoo or seek a specialized graduate degree for the field. If you choose the field of stress on animals in captivity you'll probably want a PhD in Animal Physiology or a related field. To work in the field about trafficking you'll probably want to study international relations and possibly earn a JD to open doors into the non-profit world.