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An attempt to balance selection intensity and conservation of genetic diversity was made in the national program for breeding for scrapie resistance in the Netherlands. The ARR allele is associated with resistance to scrapie. In the Netherlands a breeding program was started on a voluntary basis in 2001 and starting 2004 the use of ARR/ARR rams was obligatory. In some rare breeds there were so few ARR/ARR rams that the risk of high inbreeding and associated loss of genetic diversity would be unacceptably high. Based on computer simulations predicting the inbreeding rates for several breeds exemptions on the obligatory breeding program were allowed. In this paper the ARR frequencies and associated inbreeding rates are analyzed as an indication of loss in genetic diversity during the years of scrapie selection in two breeds: the “Zwartbles schaap” (Black-blazed sheep) and the “Melkschaap” (Friesian-Zealand Milksheep).

An attempt to balance selection intensity and conservation of genetic diversity was made in the national program for breeding for scrapie resistance in the Netherlands. The ARR allele is associated with resistance to scrapie. In the Netherlands a breeding program was started on a voluntary basis in 2001 and starting 2004 the use of ARR/ARR rams was obligatory. In some rare breeds there were so few ARR/ARR rams that the risk of high inbreeding and associated loss of genetic diversity would be unacceptably high. Based on computer simulations predicting the inbreeding rates for several breeds exemptions on the obligatory breeding program were allowed. In this paper the ARR frequencies and associated inbreeding rates are analyzed as an indication of loss in genetic diversity during the years of scrapie selection in two breeds: the “Zwartbles schaap” (Black-blazed sheep) and the “Melkschaap” (Friesian-Zealand Milksheep).

National legislation to breed for scrapie resistence was changed in 2007. The obligatory use of ARR/ARR rams was suspended in that year. Breeding for scrapie resistance is, however, still stimulated and not suspended. In this report a general advice on how to continue breeding for scrapie resistance is presented. A one day meeting on breeding in small breeds of sheep and goats provided further information and attracted much interest. A specific analysis was carried out for 2 small Dutch sheep breeds, the Black blazed sheep (Zwartbles) and the Dutch Milksheep (Melkschaap) In 2007 is de nationale regelgeving, gericht op selectie tegen scrapie gevoeligheid, gewijzigd. De verplichte inzet van ARR/ARR rammen is beëindigd. In dit rapport geven we een algemeen advies hoe het beste tegen scrapiegevoeligheid kan worden geselecteerd. In dit kader is ook een themadag over fokkerij inteelt in kleine populaties georganiseerd. Daarnaast zijn 2 Nederlandse rassen, Zwartbles en Friese/Zeeuwse Melkschaap, nader geanalyseerd en is een advies voor deze stamboeken opgesteld om inteelt te beheersen

National legislation to breed for scrapie resistence was changed in 2007. The obligatory use of ARR/ARR rams was suspended in that year. Breeding for scrapie resistance is, however, still stimulated and not suspended. In this report a general advice on how to continue breeding for scrapie resistance is presented. A one day meeting on breeding in small breeds of sheep and goats provided further information and attracted much interest. A specific analysis was carried out for 2 small Dutch sheep breeds, the Black blazed sheep (Zwartbles) and the Dutch Milksheep (Melkschaap)