I've never hunted for deer, but why is it necessary to cut out the deer's anal membrane?
EDIT: didn't find anything about tying off the anus, but I did find a picture-filled DIY on a hunting forum. Did you know that you have to cut off the deer's testicles and penis? No...me neither (Caution- it's a wee bit graphic so don't click if you're squeamish:
http://huntingnut.com/index.php?name=News&file=article&sid=4)