Gelding
A gelding (/ˈɡɛldɪŋ/) is a castrated male horse or other equine, such as a pony, donkey or a mule. The term is also used with certain other animals and livestock, such as domesticated camels. By comparison, the equivalent term for castrated male cattle would be steer (or bullock), and wether for sheep and goats.
Castration allows a male animal to be more calm, better-behaved, less sexually aggressive, and more responsive to training efforts. This makes the animal generally more suitable as an everyday working animal, or as a pet in the case of companion animals. The gerund and participle "gelding" and the infinitive "to geld" refer to the castration procedure itself.