Dr. Gus Cothran, of Texas A&M School of Veterinary Medicine & Biomedical Sciences (CVM), has completed a study that determined that the Cleveland Bay breed of horse has the third-lowest genetic variation level of all domestic horse breeds. The only two breeds with less genetic diversity are the Friesian and the Clydesdale—both of which are notoriously inbred.
Horse breeds that lack genetic diversity are more at risk for a variety of health conditions and their populations are less stable. Breeds with a wider range of genetic diversity have a wider variety of traits and are more stable, mainly because the disease traits are more diluted, says Cothran.
The Cleveland Bay is native to the United Kingdom and the only native warmblood in the region; it is believed there are only about 900 Cleveland Bay horses alive. The breed is considered critically endangered by the Livestock Conservancy.
Cothran and his team took samples of hair from 90 Cleveland Bays and compared them to one another and to samples from other breeds of horse to determine the genetic diversity, which is key to securing the breed's future. Cothran determined that both the mean allele number and the heterozygosity were below average, meaning there is lower than average genetic diversity in the breed. This lack of genetic diversity could lead to inbreeding, which can causes diseases, deformities or low fertility.
The study also evaluated the diversity between the Cleveland Bay and other breeds and determined that the Cleveland Bay is genetically unique from other breeds. Cothran hopes that his study will guide conservation efforts as well as inform breeds on how they can further their horses' genetic lines.
Read more at Phys.org
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