Doesn't this fly right in the face of the Libertarian concept of Property Right's though?
I mean, hey.. your animal.. Who is Government to tell you how to use it?
Not really. Bestiality is an initiated act of aggression that has no beneficial purpose. If I raise sheep and slaughter the lambs, I am providing sustainence for others while rightfully receiving remuneration for my hard work and care.
If I commit an act of bestiality in public I am neither providing life to my fellow man (meat) or treating the animal with respect. I have committed a crime and should be punished.