Don't feel bad about being zoo -- as I said, there is nothing wrong with being sexually attracted to animals, and it is not wrong to have sex with an animal. People have been conditioned by society to think it is "wrong", and people need to "break out" of that conditioning.
The reasons society give for why it is "wrong" are not rational, especially when people eat meat without giving it a second thought (i.e. they are OK with animals being killed in slaughterhouses, something far worse than sex with animals).
If your conscience tells you that you are zoo, then you should accept and embrace that aspect of yourself. Do not feel "worthless" for being a zoo. In fact, being zoo is what makes life meaningful for a lot of zoos.
I am with Zoo50 here. I think the primary reason that some people feel guilt is due to social and religious brainwashing, and even the social brainwashing I think stems from religious brainwashing. Even people that are not religious are drawn into the brainwashing that sex with animals is bad. Because society as a whole was mostly religious in the past, (even if not still so today), the religious morals are still an integral part of how most people think.
There are countries where christian, muslum, Jewish, catholic etc., never existed, and those countries as a whole do not have the setback about sex with animals the way the countries that have or once had those religious do.
I myself do not come from a religious family, and never had religious friends. I suspect it may be partially due to this reason that I never even once had any feeling of guilt over having desires or outright sex with animals. I started when I was 11. I hid it from everyone because I did realize that it was not normal behavior, and I did not want anyone to know, but I was neither ashamed of it, nor did I feel guilt.
That said, I also hid the fact that I masturbated, both from my parents and my friends until I was in my 20's. Not due to the feeling of guilt, shame or remorse, but simply because I was shy about it at the time.
My basic feeling is like many others here.
So long as you are not hurting an animal, I do not personally think there is anything to feel guilty about.
Show me a stallion that feels guilty about shoving his penis into a human and having an orgasm from it. Show me a mare that feels guilt about shoving her wet and winking vulva in someone's face! A male dog that feels guilt about humping and getting himself knotted to a human.
I feel that if the animal does not feel guilty, then why should I?