1.   Mad cow disease is believed to spread through recycled meat and bones from infected animals used in cattle feed.

2.   Mad cow disease is believed to spread through cattle feed using recycled meat and bones from infected animals.

3.   Mad cow disease or BSE, which affects animals, is believed to spread through recycled meat and bones from infected animals used in cattle feed.

4.   Mad cow disease, or bovine spongiform encephalopathy, is believed to spread through recycled meat and bones from infected animals used in cattle feed.

5.   Mad cow disease, also called bovine spongiform encephalopathy or BSE, is believed to spread through recycled meat and bones from infected animals used in cattle feed.