The stables were an area in the farm, where horses eat, and sleep at as people use them for riding in races for dozens of people to see, or take a look at them whenever the company decided to throw petting zoos at the farm. Most of your siblings have become horses, especially if their genders were swapped during the changes.
As you entered the stables, the second you see the farmhands, they checked for anything you would be holding, or wearing, because according to the sign in front of the gate you saw, clothing wasn't allowed in the stables at all. Just after you checked, you saw two horseshoes on matching cushions on two separate podiums. You weren't exactly sure why the stables have weirdly colored horseshoes on podiums, but the farmhands got ready with which horseshoe you'll decide to choose.