what's the point of doing that? There is only two reasons for sex.
1. It feels good
2. Reproduction
Humans can only reproduce by mating with other humans, and evolution removes those that enjoy sex with other animals because it is less likely that their genome will pass on. Now I know someone will say homosexuality. Well, homosexuality isn't that simple since many gays until recently married the opposite sex since homosexuality was seen as a sinful act so their genome will continue. Homosexuality can range. Some may only want to have sex with the same sex while some can tolerate both. Bisexuals can still pass on their genes.
So in a long run, there is nothing reproductively beneficial by having sex with animals, but if that doesn't concern you, then there isn't much I can say though most animals have sex with humans against their will which is why animal sex is much different than homosexuality because homosexuality is a mutual love for each other. It's hard to exchange information with an animal.
