KFPS thematic meeting: working on genetic management plan for Friesian horse


November 18, 2022

Together with Wageningen University & Research and the Dr. van Haeringen Laboratory the KFPS seeks to set up a data base with DNA information and status of hereditary defects in the population for the purpose of a genetic management plan. The objective of this plan is to select based on the phase-out of hereditary defects, to prevent new defects and at the same time to preserve genetic diversity, is what the first thematic meeting in Leeuwarden on Thursday the 17th of November made clear.

DNA testing of next year’s foals

Roughly 150 KFPS members came to Leeuwarden, where extra seats had to be brought in to accommodate all the members interested in the clarification of the research programme ‘Preservation of the Friesian Horse’. ‘We have the same goal, the same good cause: the Friesian horse’, is how KFPS Chairwoman Tineke Schokker opened the evening. ‘We hope to take the first step in this process this evening.’ This first thematic meeting started with the presentation of the research the KFPS is planning to launch next year by conducting extensive DNA testing on the estimated 3500 foals to be born next year.

Genetic bottleneck: loss of variation

Wageningen UR researchers Bart Ducro and Marije Steensma unfolded the plans and background information. ‘In the past the Friesian horse has gone through several periods of a drastic decrease in population which was then followed by a period of growth. This is what we call genetic bottlenecks which caused a decline in genetic variation’, Marije Steensma explains, who herself owns a Friesian broodmare together with her father. ‘So this research concerning the Friesian horse is of personal interest to us too.’

In combination with the closed character of the Studbook and intensive use of a limited number of popular stallions in the past as well as in the present, a surge in inbreeding and the risk of hereditary defects are lurking in the background. ‘Right now inbreeding increase lies between 0.5 and 1%, which is lower than the threshold value of 1% considered as ‘dangerous’ by the FAO. Nevertheless, that figure for inbreeding is still too high and presents the inherent risk of hereditary defects’, says Marije, mentioning examples such as aortic rupture and oesophageal paralysis, but also stomach rupture and reduced fertility. ‘Every human as well as animal has ~3% flaws in the genes. That is no problem as long as the parents are not related, but as soon as related individuals are paired to each other then this increases inbreeding and there is a risk the same flaws will be passed on. This can lead to the occurrence of hereditary defects.’

Research in America

Some hereditary issues appear to be related to the connective tissues, in other words a collagen problem.’ This is the subject of research carried out by the Fenway Foundation and the University of Kentucky in America. The research underway in Wageningen UR focuses on constructing a ‘genetic map’ of the Friesian horse. This should help to get a clear idea of the current status of genetic diversity as well as the frequency and relatedness of hereditary defects. Devising ‘simple’ DNA tests such as for hydrocephaly and dwarfism is by far not straightforward, Marije pointed out. ‘Those DNA tests help us to avoid risky matches whilst horses with carrier status can still be used for breeding.’ Research into the genetic background for other hereditary defects such as oesophageal dilation are still in full swing at the Fenway Foundation and the University of Kentucky. ‘This might prove to be more difficult because we still don’t know whether they are passed down via a single gene or whether multiple genes play a role.’

Unique research worldwide

The KFPS is going to ask its members to approve the inclusion of this DNA test for all foals from 2023 onwards. The research breaks down into four steps. The so-called 80K SNP test involves the recording of 80,000 base pairs on the genome in order to define the genetic diversity, followed by the development of a breed-specific reference genome. ‘The Friesian horse is unlike any other horse’, Marije explains. It is important to have our own ‘template’ that can be used to measure up against other genomes of individual Friesian horses. ‘This research is unique in the world. There are more breeds battling against hereditary defects, but those have as yet not embarked on research to solve the problem and preserve their genetic diversity.’

Step number three of the research programme is aimed at detecting potentially lethal, hidden mutations, in other words defects that result in non-viable animals, resulting in for example dropped/slipped foals. ‘The more animals that can be genotyped with the 80K SNP test, the more likely it is we are going to find something’, Marije added, pointing out that all these data make it possible to map out the frequency and relatedness of known as well as hidden defects. ‘Then we can prioritise on the basis of seriousness and frequency whilst preserving genetic diversity.’ So is a pure-bred breed still feasible? This is the question that’s on the table now. ‘It certainly is the objective, but we also ask ourselves what the effect of cross-breeding would be, it is an option.’

Three Dutch and three foreign meetings

After the first meeting in Leeuwarden subsequent meetings will follow in Zwolle and Eindhoven next week. English as well as German translations will be presented via livestream for the members in foreign countries. The final approval of these plans hinges on the approval of the Member Council on Friday the 25th of November.

Meetings in Zwolle and Eindhoven are still open for people who wish to join. Please sign up via the office (0512 523888) or email: evelinevankooten@kfps.nl

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