Southdown sheep smaller scale breeders of sheep. It has been split into two sub-breeds. The Southdown raised by commercial growers today, is larger than the "traditional" Southdown of years past. North American Southdowns are also taller than their English counterparts. The original blood line of the English Southdowns are the "Baby Doll" Southdowns in the US. They have been selected specifically for their smaller size of the original blood lines and a focus on wool and hobby breeding rather than commercial meat production. In California and New Zealand, they are placed in vineyards to graze weeds because they are too short to
Breed registry stud book is a stud book or breed registry that does not accept any outside blood. The registered animals and all subsequent offspring trace back to the foundation stock. This ensures that the animal is a purebred member of the breed. In horses, an example of a closed stud book is that of the Thoroughbred, with a stud book tracing to 1791. The American Kennel Club is an example of a kennel club with primarily closed books for dogs; it allows new breeds to develop under its Foundation Stock Service, but such dogs are not eligible for competition in AKC