To breed with your own racehorse still requires you to place your horse in the stud farm, set a
minimum price, and select the duration of your stay. If you choose to breed within your own
stable, the minimum breeding price you have set will be automatically discounted by 35%
You can also read our article here for a detailed explanation about breeding
https://medium.com/@zed_run/breeder-owner-bonus-301656d4591