Genetic analysis of ten sheep breeds using microsatellite markers

The genetic variability of 257 sheep from 10 breeds; North Country Cheviot (NCC), Cheviot (CHE), Dorset (DOR), Suffolk (SUF), Scottish Blackface (SBF), Texel (TEX), Romanov (ROM), Finnish Landrace (FIN), Icelandic (ICE) and Red Masai (MAS) was assessed using 10 microsatellite loci. The average number of alleles per locus was 4.3 in ROM, 5.0 in MAS, and spanned a narrow range (5.4 to 6.0) in the other breeds. Estimates of expected heterozygosity (H E ) of the breeds varied within 0.05 point of each other (0.62 in FIN to 0.67 in CHE), except for ROM (0.53) which was lower (P < 0.05) than those of the other breeds, and in MAS (0.57), which was lower (P < 0.05) than those of NCC, CHE and SBF. Estimates of observed heterozygosity (H O ) of the breeds were the lowest in MAS, ROM and SUF (0.50 to 0.53) and the highest in NCC and CHE (0.64 and 0.67). The H E was greater (P < 0.01) than H O only in SUF. The results suggest that there have not been drastic losses of genetic variability in the intensely selected breeds. The low genetic variability of ROM was probably due to a small number of animals imported to North America. The British breeds (NCC, CHE, SUF, DOR, SBF) were genetically close to each other, as were the North European breeds (ROM, ICE, FIN). MAS was remotely related to the British breeds, but it was surprisingly close to the North European breeds. TEX was more closely related to the British breeds than to the North European breeds. More than 90% of 1000 simulated individuals from each breed were assigned to the correct breed, indicating that this panel of markers is useful for the identification of breed membership of individual animals, and could be used to protect the integrity of registered breeds. Key words: Sheep, genetic variability, genetic distance, microsatellites