Every year more than 10 billion mammals, birds are slaughtered in the United States for their flesh and their skin. Approximately around hundred and thirty four millions of these creatures were killed in the name of sport and in the field of science and research, another twenty to seventy million animals were killed. Animal rights activists have become more violent on this issue of using the animals for testing medicine and other experiments. This is otherwise called as animal liberation and their basic demand is that even animals should be treated and considered as the interests of humans and they should not be used for food, clothing or for any entertainment purpose and in scientific research.