Studbook selection is a process used in certain breeds of horses to select breeding stock. It allows a breed registry to direct the evolution of the breed towards the ideal by eliminating unhealthy or undesirable animals from the population. The removal of individuals from a population is called culling, and does not suggest killing the animal in question. Typically, culls are castrated or they and their offspring are unable to be registered.

The Oldenburg or Oldenburger is a warmblood horse from the north-western corner of Lower Saxony, what was formerly the Grand Duchy of Oldenburg. The breed was built on a mare base of all-purpose farm and carriage horses, today called the Alt-Oldenburger. The modern Oldenburg is managed by the Association of Breeders of the Oldenburger Horse, which enacts strict selection of breeding stock to ensure that each generation is better than the last. Oldenburgers are tall sport horses with excellent gaits and jumping ability. The breeding of Oldenburg horses is characterized by very liberal pedigree requirements and the exclusive use of privately owned stallions rather than restriction to a state-owned stud farm.