After castration, the bull's behavior may become calmer, and it may gain weight more easily due to the hormonal changes. It is no longer driven by the desire to mate and its aggression may decrease, making it potentially safer to handle. Castrated bulls are often referred to as "steers" or "oxen" and may be used for various purposes, such as draft work (pulling carts or plows) or meat production.
As for the breeding bulls that are no longer suitable for breeding purposes but are still relatively young and healthy, they may be sold to other farmers or ranchers who are interested in using them for natural mating or as a source of semen for artificial insemination. This practice is less common compared to castration, but it depends on the individual circumstances, breed, and the market for breeding bulls.