Okay, so I have seen many threads about people's farm animals disappearing. This might be the solution for those kinds of problems. Give me your feedback if it worked or not because I tried it on a small scaled farm and it worked.
http://www.youtube.com/watch?v=BWj0LaQcedg&list=UUChaPGDM0d6YQv2yyVoVfGg&index=1&feature=plcp
http://www.youtube.com/watch?v=BWj0LaQcedg&list=UUChaPGDM0d6YQv2yyVoVfGg&index=1&feature=plcp