Populatie analyse van de Schoonebeeker en het Drents heideschaap: Inzicht in de genetische gezondheid van de Schoonebeeker en Drents heideschaap populaties en adviezen voor de toekomst

The Drenthe heath sheep and the Schoonebeeker are two of the rare native livestock breeds in the Netherlands. Monitoring trends in the number of breeding animals and the rate of inbreeding is essential for the conservation of rare breeds. In 2024, the Center for Genetic Resources, the Netherlands (CGN) carried out a population genetic analysis for the Drenthe heath sheep and the Schoonebeekers. The results show a downward trend in the number of breeding stock and lambs born per year for both breeds and a disproportionate share from the most commonly used rams. Unfortunately, the inbreeding rate could not be reliably determined due to the large amount of missing data in the studbook for both breeds. The advice is therefore to first focus on developing a studbook file that is as complete as possible with as many pedigrees as possible. In the second part of the study, various measures were compared using computer simulations to determine how a reduction in the expected rate of inbreeding could be achieved. The studbook already uses a breeding restriction for the rams and the simulations showed that this breeding restriction indeed has a beneficial effect on reducing the inbreeding rate. Stricter breeding restrictions and breeding circles have only a very limited effect. The selection of breeding animals with the lowest mean kinship will result in the lowest expected rate of inbreeding. However, this method is only possible with a complete and reliable pedigree registration. A combination of measures, such as maintaining the breeding restriction and, in the future, possibly selecting for low mean kinships, will have the most desired effect.