Stud work...its the same as entering to a degree..pardon the pun..but early success can make all the difference..using a 14 month dog to mate a bitch isnt exactly going to strain tendons, break bones or put hips out..in some cases it speeds up the mental maturity, settling them down, and as far as producing too many pups, its his dog, he can do what the f**k he likes with it,