Pure vs Mixed Breeds

The argument of pure vs mixed breeds is complicated and debatable, further information is provided below.

Summary

At the root, pure breeds can be defined as an insistency on genetic predictability and consistency that arises from a careful consideration of the breeds that are interbred or rather, not. Sometimes a pure breed is defined by the status of their studbook, stating that a breed is only pure if they have a closed studbook, although there are degrees to this as well. Despite the prestige that comes with purebred horses, it is important to consider that there are many advantages to a mixed breed. Mixed breeds are defined usually by an open herd book a crossing between two or more distinct breeds. Like with pure breeds, there are degrees to the openness of the stud book, which can influence your decision when choosing whether or not to cross two horses.

• Pure breeds are defined as being highly genetically predictable and having a closed studbook
• Mixed breeds have a large genetic pool and open studbooks
• A consideration of the advantages and disadvantages of both should be considered

Pure Breeds

The definition for whether or not a breed is pure is not as simple as looking back at the history of the horse. Horses have been interbreeding, with and without human intervention for millennia and while there is a certain prestige associated with a pure bred horse, sometimes that is all it is, prestige. If a pure bred horse is based on the status of the studbook for that breed, then only breeds with closed studbooks would be considered pure. A closed studbook means that only foals with registered parents can register, and depending on the degree that the studbook is closed, the foal might only need one parent registered, or multiple tests to ensure that they carry certain characteristics that also qualify them for registration.However, some breeds that have a closed studbook are technically crosses between two horses, in a way that eventually led to a separate breed and thus, registry.

Other arguments for the definition of a pure breed would be based on the predictability and consistency of the genetic transfer and the characteristics of the foal. Having closed studbook and consistent genetics does have its advantages, in that the foal’s characteristics and phenotypes are almost guaranteed, however it does close the gene pool and increase the risk genetic mutations or inbreeding. Arguably the oldest breed is the Arabian, whose genetic make-up can be found in nearly all of the current horse breeds that we have today. Another well known pure breed is the Thoroughbred who is defined by not only a tightly regulated studbook but also a link back to three foundational sires, the Darley Arabian, the Godolphin Arabian and the Byerly Turk.

Other arguments for the definition of a pure breed would be based on the predictability and consistency of the genetic transfer and the characteristics of the foal. Having closed studbook and consistent genetics does have its advantages, in that the foal’s characteristics and phenotypes are almost guaranteed, however it does close the gene pool and increase the risk genetic mutations or inbreeding. Arguably the oldest breed is the Arabian, whose genetic make-up can be found in nearly all of the current horse breeds that we have today. Another well known pure breed is the Thoroughbred who is defined by not only a tightly regulated studbook but also a link back to three foundational sires, the Darley Arabian, the Godolphin Arabian and the Byerly Turk.

Some other well-known pure breeds

• The Icelandic Horse --> it was isolated geographically and thus developed separately
• Friesans --> they have one of the most tightly closed studbooks and strict requirements for registration

Mixed Breeds

Almost all horses that you will have encountered in your day to day life will have been mixed breeds, crossed with two different breeds in order to create a foal that will fill the desired niche. Riding school horses, show jumpers and dressage horses all have mixed breeds competing at the highest levels.

Generally they are defined as having an open studbook, unlike pure breeds and which can, like pure breeds can have varying degrees of openness. A wide open studbook would be based on a general characteristic, such as colour or movement. Breeds with open studbooks in include the Hanoverian, where mares eligible for entry into the breeding program include Thoroughbreds, registered Arabs and Anglo-Arabs. Mares with excellent movement would also be considered to be register into the breeding program, as movement is a key aspect of the breeds characteristics.

There are many benefits to a mixed breed horse, you have more options to choose from and a wider genetic pool that reduces the risk of inbreeding. However, it should be noted that the results can sometimes be less predictable, precisely because the gene pool is so wide. However, many mixed breeds also have standards for registration and genetic testing can help determine the likelihood of certain genetic diseases and phenotypes in the foal.

Genetic Testing: Practical Horse Genetics

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