If you missed the recent announcement, the KFPS revealed that the kinship percentage for all living Friesians is now available in the My KFPS database and will be updated annually in the fall around the November timeframe. Previously, kinship data was only published for Studbook stallions and mares aged three years and older. In recent years, there have been growing calls for the kinship of all horses to be published, particularly for foalbook stallions used for breeding outside of the Netherlands. Now, kinship percentages are accessible for all horses, including foals, geldings, and foal book stallions. This development represents a significant milestone in assisting current and future owners in making more informed purchasing and breeding decisions based on calculations that impact the population's health.
What Is Kinship?
Kinship serves as a means to determine the genetic relatedness of a horse to the rest of the population. It also assists the Studbook in monitoring and managing inbreeding across generations by offering insights into population statistics and trends. Currently, the average kinship among KFPS Friesians is about 17.8%. It's crucial to understand that as the population evolves, kinship does, too, especially for Studbook stallions. The more offspring a stallion has, the more related he becomes to the rest of the population.
Why is Kinship Important?
High kinship, meaning a high degree of genetic relatedness between individuals in a population, can lead to health problems. It increases the likelihood of inheriting recessive genetic disorders, where both parents must carry the defective gene for a disease to manifest in the offspring. When individuals within a close family reproduce, the chance of inheriting these harmful recessive genes becomes higher, potentially causing genetic diseases that might be rare in a wider population.
One major way that genetic diversity is lost from domestic animal breeds is through artificial selection. In wild animal populations, most animals, regardless of sex, produce offspring at some point in their lives and pass their genes to a new generation. The progeny that inherit the best combinations of genes have an advantage at surviving and reproducing themselves, while those that are not as lucky are culled by natural selection. Thus, natural selection favors behaviors and traits that benefit an animal’s survival and reproduction, whereas artificial selection favors traits or characteristics that humans define as desirable.
Artificial selection can occur in both open and closed populations of animals. Open populations allow individuals to move in and out of the population, leading to greater genetic diversity. Conversely, a closed animal population does not experience movement and is, therefore, less genetically diverse. In a closed population managed by artificial selection, such as KFPS Friesians, kinship and inbreeding are extremely important tools to help the Studbook and its members preserve and encourage genetic diversity.
How Can Kinship Be Used Effectively?
To address the rising issue of inbreeding, the KFPS recommends utilizing stallions with low kinship for breeding purposes. Low kinship is thus regarded as a valuable trait for prospective breeding stallions. Although stallions must demonstrate their suitability for a breeding license in all other areas, those with low kinship are afforded more opportunities to prove themselves during the stallion selection process.
Breeders aiming to produce noteworthy colts or those aspiring to breed a stallion eligible for a breeding license should consider the emphasis on kinship when selecting a stallion for their mare. The kinship level in potential breeding mares is even more critical, as it poses a greater limitation for breeders who have a wide range of stallions to choose from when pairing with their individual mare.
The KFPS advises breeders to initially select stallions that, when paired with their mares, result in no more than a 5% inbreeding coefficient over six generations. Subsequently, stallions with a lower kinship percentage should be prioritized over those with higher kinship in breeding selections to preserve genetic diversity within the population.
It’s Up to the Breeders and the Buyers
Ultimately, the value of kinship is determined by breeders and buyers. Breeders are responsible for the market supply, while buyers drive the market demand. Although the Studbook can offer guidance on prioritizing low kinship, its success depends on breeders adhering to this advice. Additionally, buyers, especially those unfamiliar with the breed, need to be informed about the importance of low kinship and possibly be prepared to invest more in these horses if they recognize their value.
Despite a growing demand among members to address health concerns within the breed, especially regarding genetic diseases, the market has not yet adapated to prioritize low kinship on a broad scale. Unless there are changes that incentivize genetic diversity in the inspection process, particularly for mares, or new Studbook polices that emphasize low kinship, for now, it appears the majority of breeders and buyers are willing to hedge their bets in favor of predicates and premiums over genetic diversity. Only time will tell if that will change.
References
Updated in MyKFPS: relationship percentage. The Phryso. December 2nd, 2024. Online
The Friesian Horse. Koninklijke Vereninging Het Friesch Paarden-Stamboek. 2019.
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Thank you for this incredibly informative article - easy to understand and educational!