Acrossbreed is an organism withpurebred parents of two different breeds, varieties, or populations. A domestic animal of unknown ancestry, where the breed status of only one parent or grandparent is known, may also be called a crossbreed though the term "mixed breed" is technically more accurate.Outcrossing is a type of crossbreeding used within a purebred breed to increase the genetic diversity within the breed, particularly when there is a need to avoidinbreeding.
In animal breeding,crossbreeds are crosses within a single species, whilehybrids are crosses between different species. In plant breeding terminology, the termcrossbreed is uncommon, and no universal term is used to distinguish hybridization or crossing within a population from those between populations, or even those between species.
Crossbreeding is the process of breeding such an organism. It can be beneficially used to maintain health and viability of organisms. However, irresponsible crossbreeding can also produce organisms of inferior quality or dilute apurebred gene pool to the point ofextinction of a givenbreed of organism.[1]
Cats: The many newly developed and recognizedbreeds of domestic cat are crossbreeds between existing, well-established breeds (sometimes with limitedhybridization with some wild species), to either combine selected traits from thefoundation stock, or propagate a raremutation without excessiveinbreeding. However, some nascent breeds such as theAegean cat are developed entirely from a locallandrace population. Mostexperimental 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.[2]
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 individual stockman.[3]
Llamas: Results of crossbreeding classic and woolly breeds of llama are unpredictable. The resulting offspring displays physical characteristics of either parent, or a mix of characteristics from both, periodically producing a fleeced llama. The results are increasingly unpredictable when both parents are crossbreeds, with possibility of the offspring displaying characteristics of a grandparent, not obvious in either parent.[4]
Dogs:
Acrossbred dog is a cross between two (sometimes more) known breeds, and is usually distinguished from amixed-breed dog, which has ancestry from many sources, some of which may not be known. Crossbreeds are popular, due to the belief that they haveincreased vigor without loss of attractiveness of the dog. Certain planned crossbreeding between purebred dogs of different breeds are now widely known as "designer dogs" and can produce puppies worth more than their purebred parents, due to a high demand.
Horses:Crossbreeding horses is often done with the intent of ultimately creating a new breed of horse. One type of modern crossbreeding in horses created many of thewarmblood breeds used in thesport horse disciplines, usually registered in anopen stud book by astudbook selection procedure that evaluates conformation, pedigree and, in some animals, a training or performance standard. Most warmblood breeds began as a cross ofdraft horse breeds onThoroughbreds, but have, in some cases, developed over the past century to the point where they are considered to be a true-breeding population and have aclosed stud book. Other types of recognized crossbreeding include that within theAmerican Quarter Horse, which will register horses with one Thoroughbred parent and one registered Quarter Horse parent in the "Appendix" registry, and allow such animals full breed registration status as Quarter Horses if they meet a certain performance standard. Another well-known crossbred horse is theAnglo-Arabian, which may be produced by a purebredArabian horse crossed on a Thoroughbred, or by various crosses of Anglo-Arabians with other Anglo-Arabians, as long as the ensuing animal never has more than 75% or less than 25% of each breed represented in its pedigree.
Ahybrid animal is one with parentage of two separate species, differentiating it from crossbred animals, which have parentage of the same species. Hybrids are usually, but not always, sterile.[5]
One of the most ancient types of hybrid animal is themule, a cross between a femalehorse and a maledonkey. Theliger is ahybrid cross between a malelion and femaletiger. Theyattle is a cross between acow and ayak. Other crosses include thetigon (between a male tiger and female lion) andyakalo (between a yak and anAmerican bison). The Incas recognized that hybrids ofLama glama (llama) andVicugna pacos (alpaca) resulted in a hybrid with none of the advantages of either parent.[6]
At one time it was thought that dogs and wolves were separate species, and thecrosses between dogs and wolves were called wolf hybrids. Today wolves and dogs are both recognized asCanis lupus, but the old term "wolf hybrid" is still used.
A mixed-breed animal is defined as having undocumented or unknown parentage, while a crossbreed generally has known, usuallypurebred parents of two distinct breeds or varieties. A dog of unknown parentage is often called a mixed-breed dog, "mutt" or "mongrel." A cat of unknown parentage is often referred to as adomestic short-haired ordomestic long-haired cat generically, and in some dialects is often called a "moggie". A horse of unknown bloodlines is called agrade horse.
A designer crossbreed or designer breed is a crossbred animal withpurebred parents, usually registered with abreed registry, but from two differentbreeds. These animals are the result of a deliberate decision to create a specific crossbred animal.[7] Less often, the animal may have more than two pure breeds in its ancestry, but unlike a mutt or amongrel, its entirepedigree is known to descend from specific known animals. While the term is best known when applied to certaindog crossbreeds, other animals such as cattle, horses, birds[8] and cats may also be bred in this fashion. Some crossbred breeders start a freestanding breed registry to record designer crossbreds, other crossbreds may be included in an "appendix" to an existing purebred registry. either form of registration may be the first step in recording and trackingpedigrees in order to develop a new breed.
The purpose of creating designer crossbreds is usually one or more of the following reasons:
Breeders of designer crossbreds borrow thetechnical language fromhybrid plant breeding: A first generation, 50–50 crossbred is anF1 cross.[7] Subsequent generations may see a purebred animal crossed back on a crossbred, creating a 75/25 cross,[7] or a BC1 or F1b "backcross."[citation needed] The breeding of two crossbreeds of the same combination of breeds, creating an F2 cross, an animal that is still a 50–50 cross, but it is the secondfilial generation of the combination.[10] An F2 cross bred to an F2 cross creates an F3 cross. Similarly, an F2 animal bred to an F1 animal creates an F2b backcross. F3 crosses and greater are called "multi-generational" crosses.[citation needed] In dog breeding, three generations of reliable documented breeding can be considered a "breed" rather than a crossbreed.[11]
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, thePoodle 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.[7] Also, because breeders of crossbred animals may be less careful aboutgenetic testing and weeding out undesirable traits,[11] certain deleteriousdominant 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.
