http://www.equineboard.com/which-pro...orses-584.html
The search function is your friend, although we really didn't get to the bottom of it in that thread either it seems.
Here's Snopes take on J-ello:
http://www.snopes.com/food/ingredient/jello.asp
Here's a nice one about glues:
http://www.answers.com/topic/glue?cat=technology
Not much info about how much glue is still made from animal parts and not synthetics though.