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 (FLN), Icelandic (ICE) and R ed Masai (MAS) was assessed using 10 microsatellite loci. The average numbe r of alleles per locus was 4.3 in ROM, 5.0 in MAS, and spanned a narrow ran ge (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 bre eds were the lowest in MAS, ROM and SUF (0.50 to 0.53) and the highest in N CC 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 geneti c Variability in the intensely selected breeds. The low genetic variability of ROM was probably due to a small number of animals imported to North Ame rica. The British breeds (NCC, CHE, SUF, DOR, SBF) were genetically close t o each other, as were the North European breeds (ROM, ICE, FIN). MAS was re motely related to the British breeds, but it was surprisingly close to the North European breeds. TEX was more closely related to the British breeds t han to the North European breeds. More than 90% of 1000 simulated individua ls from each breed were assigned to the correct breed, indicating that this panel of markers is useful for the identification of breed membership of i ndividual animals, and could be used to protect the integrity of registered breeds.