Suitability of microsatellites BM1329 and OarAElOl as markers for the introgression of the Fec^B locus into different sheep breeds

Abstract. Litter size in sheep can be improved by introgression of the Fec^B gene. Genetic markers closely linked to the Fec^B locus can be used to detect gene carriers. The efficiency of introgression can be increased by using marker assisted selection. Individuals of the prolific breeds Tyrolean Mountain sheep (n = 41), Romanov (n = 43), East Friesian Milksheep (n = 35) and Merinoland sheep (n = 265) were genotyped with the microsatellite markers OarAElOl and BMI 329 linked to the Fec^B gene to estimate allele frequencies of both microsatellites in these breeds. The frequencies of the microsatellite alleles linked to the Fec^B gene in Merinoland sheep were 0.07 and 0.1 respectively. The alleles occured also in the other breeds (Tyrolean Mountain sheep, Romanov and East Friesian Milksheep) but with mostly higher frequencies. Furthermore the segregation of the microsatellite alleles was studied in families produced by mating Merinoland sheep ewes (Fec+/Fec+) with two heterozygous Booroola Merino rams (Fec+/Fec^B) in order to use these markers within an indirect gene test. The recombination rate between BM 1329 and OarAElOl was 13 cM (LOD score 14.6).