Popular sexual mores have been put on the pedestal of popular morality for such a long time that they have gained an almost teflon-like resistance to stones cast at the irregularities in the logic of their proponents. If you try to argue them down, you end up hitting the brick wall of social acceptability. This problem makes it very difficult to claim validity for any of the arguments presented here. Animals can consent to sex with a human partner. I have been able to demonstrate this as far as it is possible to demonstrate such an abstract thing.
Animals can also actively seek out and request sexual release from a human partner.
On many occasions I have been on the receiving end of these requests. One final word on consent, before I close. The question of whether animals can consent to inter-species sex is not easy to answer. There are many cases where animals are used solely for human benefit. I am certain none of the animals involved consented to the treatment they receive.