Senior pygmy bucks are the herd sires, and are the foundation of the herd. The traits that they pass on can make or break the herd. The key to a nice buck is not how he performs in the show ring but rather, the traits that he passes on to his offspring.
Junior bucks are those under 12 months of age. A pygmy buck is capable of breeding at 4-5 months of age, and so should be separated from the does by this time. Generally, a young buck is ready for breeding, at around 7 months old. At this time they are very active and interested in the does.
Pygmy wethers are bucks that have been fixed (castrated) and can no longer reproduce. Once castrated, they lose their breeding instinct, buck masculinity and habits, plus that distinct smell of a buck goat. These boys make wonderful pets. They can also be shown. In fact, large wether classes exist at NPGA shows. Wethers compete against the breed standard, but a large percentage of the score is determined by behavior in the show ring, since they are considered pets.