KFPS Proposes Major Breeding Reforms: Will They Be Enough to Protect the Friesian Horse’s Genetic Future?
The Royal Friesian Horse Studbook is proposing significant changes to stallion selection, breeding limits, and health reporting. While the reforms reflect a growing commitment to genetic diversity and long-term breed health, important questions remain about whether they will achieve their intended goals.
The Royal Friesian Horse Studbook (KFPS) has introduced a comprehensive proposal to revise its breeding and stallion selection policies, placing greater emphasis on genetic diversity, inherited health, and the long-term sustainability of the Friesian horse. The proposal, titled One Breeding Goal, One Direction, Shared Responsibility, outlines eight principal changes intended to broaden stallion participation, reduce the rate of inbreeding, and incorporate more comprehensive genetic and health information into breeding decisions.
Perhaps most significantly, the KFPS openly acknowledges that its historically strict stallion selection procedures, combined with the disproportionate use of popular breeding stallions, have contributed to declining genetic diversity. The proposed reforms reflect a recognition that preserving the qualities of the Friesian horse requires not only selecting desirable individuals but also managing the genetic health of the population as a whole. However, the supporting documentation reveals that the proposed measures represent a compromise between what genetic research suggests may be most effective and what the organization considers practical and economically sustainable.
Why the KFPS Is Reconsidering Its Breeding Policy
According to the KFPS, the current rate of inbreeding increase is approximately 0.7% per generation, with a stated objective of reducing that rate to less than 0.5%. This figure should not be confused with an individual horse's inbreeding coefficient. Rather, it measures how quickly additional inbreeding is accumulating across generations within the population. Although the Friesian breed has made considerable progress in reducing this rate from historical levels, continued accumulation remains a concern because it can diminish genetic diversity, increase the expression of harmful recessive variants, and negatively affect characteristics such as fertility and overall health.
One of the primary contributors is the popular sire effect, in which a relatively small number of stallions produce a disproportionately large share of the next generation. In a closed population such as the Friesian breed, repeated use of the same stallions and their descendants increases the representation of certain ancestral lines while others become progressively less common. Over time, this reduces the genetic options available to future generations.
Research published in 2024 by Marije Steensma and colleagues at Wageningen University & Research and the KFPS illustrates the problem. In 1980, the ten most frequently used stallions accounted for approximately 75% of Friesian foals born that year. By 2022, that figure had declined to approximately 35%, representing considerable improvement. However, the researchers found that much of this reduction resulted from an increase in the number of approved stallions rather than a more equal distribution of breeding contributions.
This distinction was also central to our recent article, More Stallions, Same Gene Pool: What a Brazilian Friesian Study Reveals About Breeding Diversity. That study examined pedigrees from 411 registered Friesians in Brazil and found that just three stallions had sired approximately 36% of the horses represented in the analysis. Although the Brazilian population cannot be directly equated with the worldwide KFPS population, the findings illustrate an important principle: having more horses or breeding stallions available does not necessarily mean more genetic diversity is being preserved. What matters is how broadly breeding contributions are distributed and how closely related those contributing horses are to the population.
Reducing the Influence of Popular Stallions
One of the most consequential changes proposed by the KFPS is a gradual reduction in the number of annual coverings permitted per approved stallion. Beginning in 2027, the maximum would be 180 coverings, declining to 160 in 2028, 140 in 2029, and 120 annually beginning in 2030. These limits would apply to all approved stallions throughout their breeding careers, rather than primarily restricting stallions during their initial years of approval.
The objective is straightforward. By limiting the influence of individual popular stallions, additional breeding opportunities should become available to other approved stallions, encouraging broader genetic contributions to the next generation. The proposed limit of 120 coverings also reflects the decline in annual Friesian foal production, from approximately 6,000 when the original restrictions were introduced in 2003 to roughly 4,000 today.
The KFPS intends to monitor the number of coverings and foals produced, using a maximum contribution of approximately 3% of annual foal births per stallion as a guideline. The limits may also be reconsidered if the number of foals born changes substantially over several consecutive years.
Reducing the concentration of breedings among popular stallions is an important step, but its effectiveness depends on a critical consideration: where will those breeding opportunities go? If breeders simply move from one popular stallion to his son, half-brother, or another closely related stallion, much of the same ancestry may continue to dominate the population. The number of contributing stallions may increase without producing a comparable improvement in genetic diversity.
The Role of Mean Kinship: What Does the Research Tell Us?
This is where mean kinship becomes particularly important. Mean kinship estimates how closely related an individual horse is, on average, to a defined reference population. Stallions with lower mean kinship generally represent ancestry that is less common within the current breeding population and may therefore offer greater value for preserving genetic diversity. The KFPS already calculates stallion relatedness using the population of female foals born during the preceding three years, providing an established means of identifying stallions whose ancestry is comparatively underrepresented.
The 2024 research by Steensma and colleagues provides compelling evidence that managing breeding contributions according to kinship can be substantially more effective than simply applying uniform breeding limits. Using computer simulations based on the Friesian population, the researchers found that a uniform limit of 90 offspring per stallion annually resulted in a projected inbreeding increase of 0.55% per generation. When limits were stratified according to mean kinship, allowing between 60 and 120 offspring depending on each stallion's population relatedness, the projected rate declined to 0.43%. An even more restrictive strategy, selecting only stallions with below-average mean kinship, reduced the projected rate to 0.33%.
These figures represent simulated outcomes under specific assumptions, not direct predictions for the newly proposed KFPS policy. The simulations also measured offspring rather than coverings, making direct numerical comparisons inappropriate. Nevertheless, the findings demonstrate that directing breeding contributions toward genetically underrepresented stallions can be considerably more effective than applying identical numerical restrictions to every stallion.
Interestingly, the KFPS project group does not dispute these findings. Its supporting documentation explicitly acknowledges that kinship-stratified limits are scientifically more effective and that more restrictive limits may be necessary to achieve the desired rate of less than 0.5% per generation under certain modeled conditions. Yet the group ultimately recommends a uniform limit of 120 coverings.
The reasoning reflects several practical concerns. Kinship-based limits would require regular recalculation as population relationships change, potentially complicating decisions for breeders and stallion owners. Stricter restrictions on highly related stallions could also influence stud fees, reduce breeding flexibility, and introduce economic uncertainty. More broadly, the KFPS recognizes that excessively restrictive policies could discourage breeding activity, potentially creating additional challenges for an already limited population.
These concerns are legitimate. A breeding strategy must be sufficiently practical for breeders and stallion owners to participate in it, and maintaining an adequate number of foals is itself important to the population's future. However, the decision raises an important scientific question: if uniform breeding limits are less effective than kinship-stratified restrictions, will the additional measures proposed by KFPS be sufficient to achieve its stated goal?
The answer will depend largely on whether breeders actually redirect meaningful breeding opportunities toward genetically underrepresented stallions. Making those stallions available is an important first step, but their contribution to the next generation ultimately determines whether the population benefits.
Broadening Stallion Selection While Maintaining Breed Standards
The KFPS recognizes that preserving genetic diversity requires reconsidering how stallions are selected for breeding. One important proposal is the introduction of a second annual Central Examination, beginning in 2028, that would provide an alternative selection pathway for stallions with particular genetic value or demonstrated sporting ability. This would create additional opportunities for stallions with less-common bloodlines or lower population relatedness, alongside horses whose performance achievements demonstrate desirable functional qualities.
The proposal also challenges whether certain traditional exclusion criteria remain justified, particularly when those characteristics have little demonstrated relationship to health or functionality. In a closed breeding population, excluding an otherwise suitable stallion for a relatively minor physical characteristic may mean losing access to valuable ancestry that is already underrepresented.
One of the more interesting proposed changes involves white markings, which have historically been tightly restricted within Friesian breeding. The KFPS would permit white markings on the soles of the hooves and allow white hairs or markings on the head above the lower eye line without the current three-centimeter maximum diameter. These markings would be documented, while other restrictions would remain in place. The supporting documentation explains that white markings are genetically influenced but have no demonstrated negative relationship with health in the breed. The reasoning is that excluding otherwise valuable stallions because of certain markings may unnecessarily restrict genetic diversity without providing a corresponding health benefit.
Other proposed changes involve mild hoof cartilage ossification and mane crest instability. Stallions with mild ossification of the hoof's collateral cartilage would no longer automatically be excluded, provided follow-up radiographs demonstrate that the condition remains stable. Moderate or severe ossification would continue to be disqualifying. Similarly, a mild, one-sided curvature of the mane crest, classified as a C-line, would be permitted, while more pronounced S-shaped or falling crests would remain grounds for exclusion.
These changes are not intended to abandon breed standards. Rather, they reflect an effort to distinguish between characteristics that may represent meaningful health or functional concerns and those that primarily affect appearance or have limited demonstrated clinical significance. The KFPS also acknowledges that future research could identify previously unrecognized health associations, making continued monitoring and a willingness to reconsider selection criteria important.
The underlying question is whether a selection standard provides enough benefit to justify excluding genetic contributions from an already limited population. For a breed facing continued loss of genetic diversity, that distinction deserves careful consideration.
Bringing Genetic Expertise Into Breeding Decisions
Another promising element is the proposed appointment of an independent breeding advisor who would evaluate ancestry, kinship, breeding values, fertility, health information, and each stallion's potential contribution to population diversity. This advisor would provide documented recommendations to the Stallion Inspection Committee, helping ensure that genetic and population-level considerations receive consistent attention alongside traditional selection criteria.
Although the advisor would not have authority to approve or reject stallions, the proposal requires the committee to document and justify decisions that depart from those recommendations. This is an important safeguard because it establishes a formal means of incorporating genetic information into the selection process while retaining accountability for the decisions made.
The KFPS also proposes an independent audit committee to oversee whether stallion selection procedures are followed appropriately, along with a rotation system for selection committee members intended to balance experience with new perspectives.
Beyond stallion approval, a breeding advisory program being developed with Wageningen University & Research could help breeders make more informed mating decisions. The proposed system would consider population relatedness, genetic diversity, health risks, ancestry, and desirable characteristics. The project group has also discussed possible financial incentives to encourage responsible breeding choices, although those measures have not yet been developed.
These initiatives could prove particularly valuable if they encourage breeders to consider not only whether a proposed mating has an acceptable individual inbreeding coefficient, but also whether that mating contributes positively to the genetic diversity of the population. Those are related, but fundamentally different, questions.
Strengthening Health Reporting and Offspring Evaluations
The KFPS proposal also places greater emphasis on collecting and using health information, with plans to develop a more accessible reporting system in 2027. Breeders, stallion owners, and members would be encouraged to report relevant health conditions, while the studbook would establish clearer procedures for recording, evaluating, and incorporating that information into breeding decisions.
For the Fenway Foundation for Friesian Horses, this is a particularly important development. Our ongoing research into megaesophagus and associated esophageal disorders has demonstrated how challenging it can be to identify and characterize inherited conditions, especially when affected horses exhibit different clinical presentations or develop symptoms at different ages. Many inherited disorders cannot currently be identified through a single DNA test, and understanding their genetic basis requires accurate clinical diagnoses, consistent disease classification, reliable health histories, appropriate controls, and comprehensive genetic information.
Improving health reporting could provide valuable opportunities to recognize disease patterns within families and bloodlines. However, collecting reports is only the beginning. Meaningful research also requires distinguishing suspected conditions from clinically supported diagnoses and understanding how findings vary across individuals and generations. The quality and completeness of the information collected will ultimately determine its usefulness.
The proposal also revises offspring evaluations to accommodate a larger number of contributing stallions. Among the changes is a reduction from 40 to 20 in the minimum number of offspring required for certain exterior evaluations, with KFPS citing scientific support for the reliability of the smaller groups for their intended purpose. Although this may make evaluations more practical and affordable, it is important to recognize that relatively small groups cannot reliably identify uncommon inherited conditions, particularly those that develop later in life. Performance and conformation evaluations provide valuable breeding information, but they cannot independently establish that a stallion's offspring are free from inherited health risks.
Preserving genetic diversity and reducing inherited disease should therefore remain complementary objectives. Greater diversity may help reduce some risks associated with inbreeding, but it does not automatically eliminate harmful variants already present within the population. Conversely, selecting too aggressively against a particular disease, especially when its inheritance is incompletely understood, could further restrict the gene pool. Continued research, accurate health information, and carefully considered breeding decisions will remain essential.
International Breeding: Questions That Remain
For breeders outside Europe, the proposal contains provisions that deserve particular attention. The new breeding limits would not include coverings outside the European Union, and mandatory offspring evaluations would be suspended while approved stallions are stationed outside the EU. Those evaluations would resume if the stallions returned to Europe.
The KFPS explains that the current proposal focuses primarily on the European stallion selection process and that international breeding policy will require additional development. These distinctions may reflect practical challenges associated with administering breeding programs across multiple countries, but they also raise questions about how international breeding contributions will be incorporated into assessments of genetic diversity and inherited health risks.
The genetic influence of a breeding stallion is not limited by national boundaries. Through imported horses, transported semen, and shared ancestry, Friesian populations worldwide remain genetically connected. A stallion whose offspring are produced across several countries may make a substantial contribution to the broader population, even when portions of that contribution fall outside the European breeding limits.
For North American breeders, it will therefore be important to understand how the KFPS intends to monitor international breeding activity and whether future policies will address genetic contributions across the worldwide Friesian population.
Measuring Success and Looking Ahead
Perhaps one of the strongest elements of the KFPS proposal is its commitment to monitoring and evaluating results. The organization intends to publish annual information on the rate of inbreeding increase, the number of stallions actually producing offspring, the distribution of breeding contributions, population relatedness, and inherited health conditions. The proposed policy also allows for adjustments as breeding numbers change or new scientific evidence becomes available.
This commitment is important because the genetic consequences of breeding decisions take time to become apparent. A new breeding limit may immediately change how many mares a popular stallion can cover, but its effect on the population's genetic diversity cannot be fully evaluated within a single breeding season.
Ultimately, success should not be measured simply by the number of stallions approved or the number of breeders complying with the new restrictions. More meaningful indicators will include whether breeding contributions become less concentrated, whether genetically underrepresented ancestry is being preserved, and whether the rate of inbreeding increase demonstrates a sustained decline toward the established target.
The proposed changes remain subject to approval. KFPS information meetings are scheduled for October 26 and 28, followed by regional meetings where members can express their views. The Members' Council is scheduled to consider the proposals on November 26, 2026, with further amendments possible before a final decision.
Taken as a whole, the reforms represent a meaningful acknowledgment of the genetic challenges facing the Friesian horse and an effort to address them through a more comprehensive breeding strategy. The increased attention to population relatedness, broader selection opportunities, inherited health information, and long-term monitoring is encouraging. Equally important is the recognition that responsible breeding must balance genetic conservation with health, functionality, breed characteristics, and the practical realities facing breeders.
Nevertheless, the available research makes clear that preserving genetic diversity requires more than approving additional stallions or restricting the use of popular sires. It requires breeding decisions that meaningfully preserve less-common ancestry and prevent the continued concentration of genetic contributions among closely related families. The KFPS has proposed several measures intended to encourage that outcome, but whether they will be sufficient remains to be demonstrated.
For the Fenway Foundation, the central consideration is the long-term health and genetic sustainability of the Friesian horse. The proposed reforms provide an opportunity to move toward more scientifically informed breeding decisions while acknowledging the challenges involved in implementing meaningful change. The question is not simply whether these proposals represent progress, but whether they will produce the measurable and lasting improvements necessary to preserve the breed's genetic future.
Read the full English version of the new KFPS Breeding & Selection proposal:
References
Royal Friesian Horse Studbook (KFPS). (2026). Eén fokdoel, één koers, gezamenlijke verantwoordelijkheid. Additional details reviewed from the KFPS member-accessible breeding and selection policy proposal and supporting appendices.
Steensma, M. J., Doekes, H. P., Pook, T., Derks, M. F. L., Bakker, N., & Ducro, B. J. (2024). Evaluation of breeding strategies to reduce the inbreeding rate in the Friesian horse population: Looking back and moving forward. Journal of Animal Breeding and Genetics, 141, 668–684.
Botelho Rocha, I. A., Araujo, F., & Patterson Rosa, L. (2026). Pedigree-based assessment of genetic structure and disease-associated variants in Friesian horses in Brazil. Journal of Equine Veterinary Science, 160, 105860.
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