Comparison of SNP Variation and Distribution in Indigenous Ethiopian and Korean Cattle (Hanwoo) Populations

Although a large number of single nucleotide polymorphisms (SNPs) have been identified from the bovine genome-sequencing project, few of these have been validated at large in Bos indicus breeds. We have genotyped 192 animals, representing 5 cattle populations of Ethiopia, with the Illumina Bovine 8K SNP BeadChip. These include 1 Sanga (Danakil), 3 zebu (Borana, Arsi and Ambo), and 1 zebu x Sanga intermediate (Horro) breeds. The Hanwoo (Bos taurus) was included for comparison purposes. Analysis of 7,045 SNP markers revealed that the mean minor allele frequency (MAF) was 0.23, 0.22, 0.21, 0.21, 0.23, and 0.29 for Ambo, Arsi, Borana, Danakil, Horro, and Hanwoo, respectively. Significant differences of MAF were observed between the indigenous Ethiopian cattle populations and Hanwoo breed (p or =0.10 and < or =0.5) accounted for an overall estimated 73.79% of the 7,045 SNPs. The Hanwoo displayed a higher proportion of common variant SNPs (90%). Investigation within Ethiopian cattle populations showed that on average, 16.64% of the markers were monomorphic, but in the Hanwoo breed, only 6% of the markers were monomorphic. Across the sampled Ethiopian cattle populations, the mean observed and expected heterozygosities were 0.314 and 0.313, respectively. The level of SNP variation identified in this particular study highlights that these markers can be potentially used for genetic studies in African cattle breeds.

Identification of Genomic Differences between Hanwoo and Holstein Breeds Using the Illumina Bovine SNP50 BeadChip

The use of genomic information in genomic selection programs for dairy and beef cattle breeds has become a reality in recent years. In this investigation, we analyzed single-nucleotide polymorphisms (SNPs) for Hanwoo (n=50) and Holstein (n=50) breeds using the Illumina Bovine SNP50 BeadChip to facilitate genomic selection and utilization of the Hanwoo breed in Korea. Analysis of the entire genomes showed different spectra of SNP frequencies for Hanwoo and Holstein cattle. The study revealed a highly significant (p<0.001) difference between Hanwoo and Holstein cattle in minor allele frequency (MAF). The average MAFs were 0.19+/-0.16 and 0.22+/-0.16 for Hanwoo and Holstein, respectively. From the total of 52,337 SNPs that were successfully identified, about 72% and 79% were polymorphic in Hanwoos and Holsteins, respectively. Polymorphic and fixed SNPs were not distributed uniformly across the chromosomes within breeds or between the two breeds. The number of fixed SNPs on all chromosomes was higher in Hanwoo cattle, reflecting the genetic uniqueness of the Hanwoo breed. In general, the rate of polymorphisms detected in these two breeds suggests that the SNPs can be used for different applications, such as whole-genome association and comparative genetic studies, and are a helpful tool in developing breed identification genetic markers.