There are various breeding methods, such as crossbreeding, selective breeding, inbreeding, and line breeding. Most livestock breeds are maintained in purebred lines. Examples of purebred animals include the Thoroughbred and the Arabian horse, which do not tolerate any further crossbreeding. Most other breeds allow for occasional crossbreeding with foreign breeds to improve certain traits, such as the Fleckvieh from Red-Holstein. The transition from refinement crossbreeding to displacement crossbreeding can be gradual, as seen in the development of the German Holstein population. Use of crossbreeding is common among all livestock to produce high-quality animals. In cattle breeding, purebred populations are maintained by individual breeders and crossed with other breeds as needed. This is particularly important in dairy farming.