crossbreed

A crossbreed or crossbred usually refers to an animal with purebred parents of two different breeds, varieties, or populations. Crossbreeding refers to the process of breeding such an animal, often with the intention of creating offspring that share the traits of both parent lineages, or producing an animal with hybrid vigor. While crossbreeding is used in livestock breeding to maintain health and viability of the animals, irresponsible crossbreeding can also produce animals of inferior quality or dilute a purebred gene pool to the point of extinction of a given breed of animal.

In general use, the term hybrid is more often used to refer to plant breeding, such as that of Maize (corn), whereas crossbred is more often used to refer to animal breeding. Crossbreed also is used at times to refer to a domestic animal where the breed status of only one parent or grandparent is known, though the term "mixed breeding" is technically more accurate. The term outcross is used to describe a type of crossbreeding used within a purebred breed to increase the genetic diversity within the breed, particularly when there is a need to avoid inbreeding.

Crossbreeds in specific animals

Cattle

In cattle, there are systems of crossbreeding. 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 of superior animals.^[1]

Sheep

The large number of breeds of sheep, which vary greatly, creates an opportunity for cross breeding to be used to tailor production of lambs to the goal of the individual stockman.^[2]

Llamas

Crossbreeds of classic and wooly breeds of llama may not result in the desired type, and "Results are worst when crosses are bred to crosses ."^[3]

Dogs

In dogs, crossbreeding between two breeds has become very popular, due to the belief that doing so increases hybrid vigor without any loss of attractiveness of the dog.

The general public sometimes confused the term crossbred when actually referring to a mixed-breed dog (also known as a mongrel or mutt), which are less desirable and less valuable than certain planned crossbreeds. In order eliminate confusion and to enhance the marketability of crossbred puppies, breeders of crossbreds sometimes refer to them as "hybrid", reflecting a secondary meaning of hybrid that refers to breeding two different populations within a single species, similar to the terminology used to describe "hybrid corn."

Horses

Crossbreeding in horses is often done with the intent of ultimately creating a new breed of horse. One type of modern crossbreeding in horses is used to create many of the warmblood breeds. Warmbloods are a type of horse used in the sport horse disciplines, usually registered in an open stud book by a studbook selection procedure that evaluates conformation, pedigree and, in some animals, a training or performance standard. Most warmblood breeds began as a cross of draft horse breeds on Thoroughbreds, 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 a closed stud book. Other types of recognized crossbreeding include that within the American 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 the Anglo-Arabian, which may be produced by a purebred Arabian 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.

Hybrid animals

A hybrid 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.^[4]

One of the most ancient types of hybird animal is the mule, a cross between a female horse and a male donkey or ass. The liger is a hybrid cross between a male lion and female tiger. The yattle is a cross between a cow and a yak. Other crosses include the tigon (between a female lion and male tiger) and yakalo (between a yak and buffalo). The Incas recognized that hybrids of Lama glama (llama) and Lama pacos (alpaca) resulted in a hybrid with none of the advantages of either parent.^[5]

At one time it was thought that dogs and wolves were separate species, and the crosses between dogs and wolves were called wolf hybrids. Today wolves and dogs are both recognized as Canis lupus, but the old term "wolf hybrid" is still used.

Mixed Breeds

A mixed breed animal is defined as having undocumented or unknown parentage, while a crossbreed, as a rule has known, usually purebred 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 a moggy. A horse of unknown bloodlines is a grade horse.

See also

• Artificial selection
• Dog hybrids and crossbreeds
• Heterosis
• Purebred
• Selective breeding
• Outcross

References

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