One Hundred Years of Coat Colour Influences on Genetic Diversity in the Process of Development of a Composite Horse Breed.

This research article examines the impact of coat color preferences over the last hundred years on the genetic diversity of the Hispano-Arabian horse breed, using records of 207,100 horses born from 1884 to 2019.

Study Objectives and Methodology

• The researchers wanted to investigate the historical influence of coat color segregation on the genetic diversity in the development of Hispano-Arabian horses, a composite breed.
• They used pedigree records from 207,100 Hispano-Arabian horses, born between 1884 and 2019, to analyze diversity and demographic parameters.
• Although coat color doesn’t impact a horse’s breeding eligibility, the study considered it an important factor due to its potential to shed light on the gene contribution of Spanish Purebred horses (PRE).
• The lack of coat color inheritance consideration during horse registration and breeders’ dodge of historical banning policies was also assessed as potential factors influencing diversity in the breed.

Findings of the Study

• Analysis showed a relatively low diversity loss, less than 8%, possibly due to the disregarded coat color inheritance during registration and the breeders’ avoidance behavior.
• Various levels of inbreeding were detected, ranging from 1.81% in Smokey Cream horses to 8.80% in white horses.
• The study found that crossbreeding increased the likelihood of double-dilute combinations, as evidenced by an increased number of Hispano-Arabian horses displaying Pearl coats compared to Spanish and Arabian purebreds.

Historical Influence and Future Implications

• Policies that disallowed certain coat colors may have indirectly influenced a proper registration of genealogical information.
• Such bans may have led to longer generation intervals over decades, due to hiding of lineage information for unapproved coat colors.
• The study suggests that breeders’ tastes may cyclically return to officially recognized coat colors (Grey, Bay, and Chestnut/Sorrel) over time.
• Therefore, the influence of coat color on breed development should be evaluated for specific durations, rather than an accumulated long-term period.

The study highlights the complexity of breed development in horses, and the need for better understanding and managing the impact of breeders’ preferences on genetic diversity.