News
Start of a new PhD project on the genetic conservation of the Friesian horse
Starting on the 1st of February, Marije Steensma will start a PhD project at the Animal Breeding and Genomics group were she will work towards a roadmap for genetic conservation of the Friesian horse. Within this project she will be supervised by Bart Ducro, Harmen Doekes and Martijn Derks.
Genetic diversity is essential for maintaining a healthy population. However, many breeds consist of small population sizes with high inbreeding rates, which leads to low genetic diversity. High inbreeding results in homozygosity, which, in turn, can result in decreased biological fitness and expression of genetic disorders, like in the Friesian horse breed. The Friesian horse is a closed population, has passed severe bottlenecks, and has had too high inbreeding rates (>1%) for several generations. The combined result of these developments is that there are now multiple genetic disorders that threaten the health and welfare of the Friesian horse population.
An additional problem is that selection against all genetic disorders in a population is complex, given that it may compromise genetic diversity and thereby increase the risk of novel genetic disorders. To avoid such a risk, and to provide an optimal balance of selection against multiple genetic disorders and conservation of genetic diversity, Marije will work towards a roadmap for genetic conservation of the Friesian Horse.
A roadmap for genetic conservation
Marije will start her journey by developing a breed-specific reference genome for the Friesian horse: “The current reference genome is of a Thoroughbred horse and is genetically distinct from the Friesian horse,” she says. “By developing a reference genome for the Friesian horse, it is possible to fine-map breed-specific variants.” The next step will be to assess the current genetic diversity of the Friesian horse population by obtaining 80K NSP data of all the foals from 2023 (approximately 3,500 foals) and Illumina paired-end short-read sequencing data of 50 approved stallions. She will investigate the presence of hidden lethal mutations in the breed by statistical depletion (i.e. absence of homozygous animals), using 80K SNP data of approximately 7,000 foals. She will assess the frequencies, distributions and genetic correlations of known and hidden genetic disorders in the Friesian horse. Finally, by combining all the results from the abovementioned objectives, she will design a roadmap for genetic conservation, providing an optimal balance of selection against multiple genetic disorders and
conservation of genetic diversity.