Participatory identification of breeding objective traits and selection criteria for indigenous goat of the pastoral communities in Ethiopia.

A structured questionnaire, own-flock ranking experiment, and group discussions were undertaken to assess goat breeding practices and to identify traits of interest for genetic improvement of indigenous goats. Four pastoral villages in Ethiopia, namely, Jarso, Mesoya, Eleweya, and Dharito were selected based on their goat production potential, accessibility, and suitability to implement community-based breeding programs. A survey and flock ranking experiment involving 70 households and 199 goats were used. In flock ranking experiment, goat owners were asked to choose the first three superior and the worst doe within their own flock. They were also asked to provide their reason for ranking the animals. In addition, data on size traits, kid growth, kid survival, reproduction traits, and milk yield were recorded for each doe. Data obtained from questionnaire, flock ranking, and measurements were subjected to both qualitative and quantitative analysis. Large variation was observed between top and last ranked does in most of the traits and price, for example, in body weight (33.6 ± 0.88 vs. 25.2 ± 0.93 kg), doe's kid survival (92.1 ± 4.01 vs. 59.6 ± 4.48%) and doe's price (1367 ± 46.5 vs. 833 ± 46.9 (US$1 = 28.4 Ethiopian Birr) Ethiopian Birr). Mobility is practiced with a defined and known pattern; therefore, recruitment of mobile enumerators for data recording would assist in implementation of breeding programs. Breeding objective should emphasize mothering ability (kid growth and survival), milk yield of does, and coat color in all areas. Due to its good correlation with other traits like kid growth and pre-weaning kid survival, considering milk yield alone as selection criteria or giving more weight for milk yield in the breeding program could generate better genetic benefit. Setting-up breeding program should be based on full participation and context of pastoralists.

Genome-wide scan reveals divergent selection among taurine and zebu cattle populations from different regions.

In this study, to identify genomic signatures of divergent selection, we genotyped 10 cattle breeds/populations (n = 275), representing eight Ethiopian cattle populations (n = 229) and two zebu populations (n = 46) adapted to tropical and sub-tropical environments, using the high-density single-nucleotide polymorphisms (SNPs) derived mainly from Bos indicus breeds, and using five reference taurine breeds (n = 212). Population genetic differentiation (FST ) values across sliding windows were estimated between zebu and reference combined taurine breeds. The most differentiated regions (FST  ≥ 0.53), representing the top 1% smoothed FST values, were considered to represent regions under diversifying selection. In total, 285 and 317 genes were identified in the comparisons of Ethiopian cattle with taurine and Asian zebu with taurine respectively. Some of these genes are involved in stress responses/thermo-tolerance and DNA damage repair (HSPA4, HSF1, CMPK1 and EIF2AK4), pigmentation (ERBB3 and MYO1A), reproduction/fertility (UBE2D3, ID3 and PSPC1), immune response (PIK3CD and AKIRIN2) and body stature and size (MBP2, LYN and NPM1). Additionally, the candidate genes were associated with functional terms (e.g. cellular response to stress, DNA repair, inflammatory response) important for physiological adaptation to environmental stresses. The results of our study may shed light on the influence of artificial and natural selection in shaping the genomic diversity of modern cattle breeds and also may serve as a basis for further genetic investigation of traits of tropical adaptation in cattle.

Detecting selection signatures between Duroc and Duroc synthetic pig populations using high-density SNP chip.

The development of high throughput genotyping techniques has facilitated the identification of selection signatures of pigs. The detection of genomic selection signals in a population subjected to differential selection pressures may provide insights into the genes associated with economically and biologically important traits. To identify genomic regions under selection, we genotyped 488 Duroc (D) pigs and 155 D × Korean native pigs (DKNPs) using the Porcine SNP70K BeadChip. By applying the FST and extended haplotype homozygosity (EHH-Rsb) methods, we detected genes under directional selection associated with growth/stature (DOCK7, PLCB4, HS2ST1, FBP2 and TG), carcass and meat quality (TG, COL14A1, FBXO5, NR3C1, SNX7, ARHGAP26 and DPYD), number of teats (LOC100153159 and LRRC1), pigmentation (MME) and ear morphology (SOX5), which are all mostly near or at fixation. These results could be a basis for investigating the underlying mutations associated with observed phenotypic variation. Validation using genome-wide association analysis would also facilitate the inclusion of some of these markers in genetic evaluation programs.

Genome-wide genetic diversity, population structure and admixture analysis in African and Asian cattle breeds.

Knowledge about genetic diversity and population structure is useful for designing effective strategies to improve the production, management and conservation of farm animal genetic resources. Here, we present a comprehensive genome-wide analysis of genetic diversity, population structure and admixture based on 244 animals sampled from 10 cattle populations in Asia and Africa and genotyped for 69,903 autosomal single-nucleotide polymorphisms (SNPs) mainly derived from the indicine breed. Principal component analysis, STRUCTURE and distance analysis from high-density SNP data clearly revealed that the largest genetic difference occurred between the two domestic lineages (taurine and indicine), whereas Ethiopian cattle populations represent a mosaic of the humped zebu and taurine. Estimation of the genetic influence of zebu and taurine revealed that Ethiopian cattle were characterized by considerable levels of introgression from South Asian zebu, whereas Bangladeshi populations shared very low taurine ancestry. The relationships among Ethiopian cattle populations reflect their history of origin and admixture rather than phenotype-based distinctions. The high within-individual genetic variability observed in Ethiopian cattle represents an untapped opportunity for adaptation to changing environments and for implementation of within-breed genetic improvement schemes. Our results provide a basis for future applications of genome-wide SNP data to exploit the unique genetic makeup of indigenous cattle breeds and to facilitate their improvement and conservation.

Linkage disequilibrium and genomic scan to detect selective loci in cattle populations adapted to different ecological conditions in Ethiopia.

Despite the wide range of observed phenotypic diversities and adaptation to different ecological conditions, little has been studied regarding the genetics of adaptation in the genome of indigenous cattle breeds of developing countries. Here, we investigated the linkage disequilibrium (LD) and identified the subset of outlier loci that are highly differentiated among cattle populations adapted to different ecological conditions in Ethiopia. Specifically, we genotyped 47 unrelated animals sampled from high- versus low-altitude environments using a Bovine 50K SNP BeadChip. Linkage disequilibrium was assessed using both D' and r(2) between adjacent SNPs. We calculated FST and heterozygosity at different significance levels as measures of genetic differentiation for each locus between high- and low-altitude populations following the hierarchical island model approach. We identified 816 loci (p < 0.01) showing selection signals and are associated with genes that might have roles in local adaptation. Some of them are associated with candidate genes that are involved in metabolism (ATP2A3, CA2, MYO18B, SIK3, INPP4A, and IREB2), hypoxia response (BDNF, TFRC, and PML) and heat stress (PRKDC, CDK1, and TFDC). Average r(2) and D' values were 0.14 ± 0.21 and 0.57 ± 0.34, respectively, for a minor allele frequency (MAF) ≥ 0.05 and were found to increase with increasing MAF value. The outlier loci identified in the studied Ethiopian cattle populations indicate the presence of genetic variation produced/shaped by adaptation to different environmental conditions and provide a basis for further validation and functional analysis using a reasonable sample size and high-density markers.