Looking for an old lost erotic literature

I remember reading this (series?) years ago. I have no clue what the name was but can remember most of the plot. It may not all be correct:

The main character, a college student signs up for a bdsm castle experience over the summer holidays. Once he arrives he is told to strip off his clothing and attach himself to a post naked in front of the castle. A girl, also from his school then shows up.

The master and mistress that run the castle come out and great them, take them inside. I think they punish one of the girls and force her to be a hucow. They brand each of the prisoners with a barcode which has a number. 1 being the most important slave. They are encouraged to pee on a slave in the ground and are given the tour. the Hucow slave is put in a tiny dungeon with a special gag that makes cow noises and fed steroids to increase milk production.

That’s all i can remember so far. Does it ring any bells??? I think I might have read it on WattPad but couldn’t tell you for sure

Source: reddit.com/r/eroticliterature/comments/l1nepr/looking_for_an_old_lost_erotic_literature