What do you call the male that is not neutreed and before he is mature?

The male that is not neutered and before he reaches maturity is typically referred to as a "buck" in the context of rabbits, goats, and some other animals. In general terms, for many species, he may simply be called an "intact male" or "young male." In dogs, cats, and other domestic pets, he is often referred to as a "puppy" or "kitten," respectively, until he matures.