developing a new animal breed. Breeders of designer crossbreds borrow the technical language from hybrid plant breeding: A first generation, 50–50 crossbred is an F1 cross. Subsequent generations may see a purebred animal crossed back on a crossbred, creating a 75/25 cross, or a BC1 or F1b "backcross." The breeding of two crossbreeds of the same combination of breeds, creating a F2 cross, an animal that is still a 50–50 cross, but it is the second filial generation of the combination. A F2 cross bred to an F2 cross creates a F3 cross. Similarly, a F2 animal bred to an F1 animal creates a F2b backcross. F3 crosses and greater are called "multi-generational" crosses. In dog breeding, three generations of reliable documented breeding can be considered a "breed" rather than a crossbreed. There are disadvantages to creating designer crossbreeds, notably the potential that the cross will be of inferior quality or that it will not produce as consistent a result as would breeding purebred animals. For example, the Poodle is a frequent breed used in creation of designer crossbreeds, due to its non-shedding coat, but that trait does not always breed true when it is part of a designer cross. Also, because breeders of crossbred animals may be less careful about genetic testing and weeding out undesirable traits, certain deleterious dominant genes may still be passed on to a crossbreed offspring. In an F2 cross, recessive genetic traits may also return if the parent animals were both carriers of an undesired trait. Crossbreeds in specific animals Cats The many newly developed and recognized breeds of domestic cat are crossbreeds between existing, well-established breeds (sometimes with limited hybridization with some wild species), to either combine selected traits from the foundation stock, or propagate a rare mutation without excessive inbreeding. However, some nascent breeds such as the Aegean cat are developed entirely from a local landrace population. Most experimental cat breeds are crossbreeds. Cattle In cattle, there are systems of crossbreeding. In many crossbreeds, one animal is larger than the other. One is used when the purebred females are particularly adapted to a specific environment, and are crossed with purebred bulls from another environment to produce a generation having traits of both parents. Sheep The large number of breeds of sheep, which vary greatly, creates an opportunity for crossbreeding to be used to tailor production of lambs to the goal of the