Genetic diversity and effective population sizes of thirteen Indian cattle breeds.

The genetic structure of a diverse set of 15 Indian indigenous breeds and non-descript indigenous cattle sampled from eight states was examined, based on 777 k single nucleotide polymorphism (SNP) genotypes obtained on 699 animals, with sample sizes ranging from 17 to 140 animals per breed. To date, this is the largest and most detailed assessment of the genetic diversity of Indian cattle breeds. Admixture analyses revealed that 109 of the indigenous animals analyzed had more than 1% Bos taurus admixture of relatively recent origin. Pure indigenous animals were defined as having more than 99% Bos indicus ancestry. Assessment of the genetic diversity within and between breeds using principal component analyses, F statistics, runs of homozygosity, the genomic relationship matrix, and maximum likelihood clustering based on allele frequencies revealed a low level of genetic diversity among the indigenous breeds compared to that of Bos taurus breeds. Correlations of SNP allele frequencies between breeds indicated that the genetic variation among the Bos indicus breeds was remarkably low. In addition, the variance in allele frequencies represented less than 1.5% between the Indian indigenous breeds compared to about 40% between Bos taurus dairy breeds. Effective population sizes (N) increased during a period post-domestication, notably for Ongole cattle, and then declined during the last 100 generations. Although we found that most of the identified runs of homozygosity are short in the Indian indigenous breeds, indicating no recent inbreeding, the high F coefficients and low F values point towards small population sizes. Nonetheless, the N of the Indian indigenous breeds is currently still larger than that of Bos taurus dairy breeds. The changes in the estimates of effective population size are consistent with domestication from a large native population followed by consolidation into breeds with a more limited population size. The surprisingly low genetic diversity among Indian indigenous cattle breeds might be due to their large N since their domestication, which started to decline only 100 generations ago, compared to approximately 250 to 500 generations for Bos taurus dairy cattle.

Strucken EM ，Gebrehiwot NZ ，Swaminathan M ，Joshi S ，Al Kalaldeh M ，Gibson JP ... -  《-》

The patterns of admixture, divergence, and ancestry of African cattle populations determined from genome-wide SNP data.

Humpless Bos taurus cattle are one of the earliest domestic cattle in Africa, followed by the arrival of humped Bos indicus cattle. The diverse indigenous cattle breeds of Africa are derived from these migrations, with most appearing to be hybrids between Bos taurus and Bos indicus. The present study examines the patterns of admixture, diversity, and relationships among African cattle breeds. Data for ~ 40 k SNPs was obtained from previous projects for 4089 animals representing 35 African indigenous, 6 European Bos taurus, 4 Bos indicus, and 5 African crossbred cattle populations. Genetic diversity and population structure were assessed using principal component analyses (PCA), admixture analyses, and Wright's F statistic. The linkage disequilibrium and effective population size (Ne) were estimated for the pure cattle populations. The first two principal components differentiated Bos indicus from European Bos taurus, and African Bos taurus from other breeds. PCA and admixture analyses showed that, except for recently admixed cattle, all indigenous breeds are either pure African Bos taurus or admixtures of African Bos taurus and Bos indicus. The African zebu breeds had highest proportions of Bos indicus ancestry ranging from 70 to 90% or 60 to 75%, depending on the admixture model. Other indigenous breeds that were not 100% African Bos taurus, ranged from 42 to 70% or 23 to 61% Bos indicus ancestry. The African Bos taurus populations showed substantial genetic diversity, and other indigenous breeds show evidence of having more than one African taurine ancestor. Ne estimates based on r and r showed a decline in Ne from a large population at 2000 generations ago, which is surprising for the indigenous breeds given the expected increase in cattle populations over that period and the lack of structured breeding programs. African indigenous cattle breeds have a large genetic diversity and are either pure African Bos taurus or admixtures of African Bos taurus and Bos indicus. This provides a rich resource of potentially valuable genetic variation, particularly for adaptation traits, and to support conservation programs. It also provides challenges for the development of genomic assays and tools for use in African populations.

Gebrehiwot NZ ，Strucken EM ，Aliloo H ，Marshall K ，Gibson JP ... -  《BMC GENOMICS》

Genetic diversity and population genetic analysis of bovine MHC class II DRB3.2 locus in three Bos indicus cattle breeds of Southern India.

The present study was performed to evaluate the genetic polymorphism of BoLA-DRB3.2 locus in Malnad Gidda, Hallikar and Ongole South Indian Bos indicus cattle breeds, employing the PCR-RFLP technique. In Malnad Gidda population, 37 BoLA-DRB3.2 alleles were detected, including one novel allele DRB3*2503 (GenBank: HM031389) that was observed in the frequency of 1.87%. In Hallikar and Ongole populations, 29 and 21 BoLA-DRB3.2 alleles were identified, respectively. The frequencies of the most common BoLA-DRB3.2 alleles (with allele frequency > 5%), in Malnad Gidda population, were DRB3.2*15 (10.30%), DRB3*5702 (9.35%), DRB3.2*16 (8.41%), DRB3.2*23 (7.01%) and DRB3.2*09 (5.61%). In Hallikar population, the most common alleles were DRB3.2*11 (13.00%), DRB3.2*44 (11.60%), DRB3.2*31 (10.30%), DRB3.2*28 (5.48%) and DRB3.2*51 (5.48%). The most common alleles in Ongole population were DRB3.2*15 (22.50%), DRB3.2*06 (20.00%), DRB3.2*13 (13.30%), DRB3.2*12 (9.17%) and DRB3.2*23 (7.50%). A high degree of heterozygosity observed in Malnad Gidda (H(O) = 0.934, H(E) = 0.955), Hallikar (H(O) = 0.931, H(E) = 0.943) and Ongole (H(O) = 0.800, H(E) = 0.878) populations, along with F(IS) values close to F(IS) zero (Malnad Gidda: F(IS) = 0.0221, Hallikar: F(IS) = 0.0127 and Ongole: F(IS) = 0.0903), yielded nonsignificant P-values with respect to Hardy-Weinberg equilibrium probabilities revealing, no perceptible inbreeding, greater genetic diversity and characteristic population structure being preserved in the three studied cattle populations. The phylogenetic tree constructed based on the frequencies of BoLA-DRB3.2 alleles observed in 10 Bos indicus and Bos taurus cattle breeds revealed distinct clustering of specific Bos indicus cattle breeds, along with unique genetic differentiation observed among them. The results of this study demonstrated that the BoLA-DRB3.2 is a highly polymorphic locus, with significant breed-specific genetic diversities being present amongst the three studied cattle breeds. The population genetics and phylogenetic analysis have revealed pivotal information about the population structure and importance of the presently studied three Bos indicus cattle breeds as unique animal genetic resources, which have to be conserved for maintaining native cattle genetic diversity.

Das DN ，Sri Hari VG ，Hatkar DN ，Rengarajan K ，Saravanan R ，Suryanarayana VV ，Murthy LK ... -  《-》

Exploring haplotype block structure, runs of homozygosity, and effective population size among dairy cattle breeds of India.

The present study aimed to explore haplotype structure, runs of homozygosity (ROH), effective population size and persistence of gametic phase among three indigenous dairy cattle breeds, viz., Sahiwal (n = 19), Tharparkar (n = 17), and Gir (n = 16) by using BovineHD single nucleotide polymorphism (SNP) genotyping assay. The filtered SNPs after quality control ranged from 44% in Sahiwal to 53% in Gir. The highest number of haplotype blocks was observed in Tharparkar (15,640) and the lowest in Sahiwal (8027) spanning 17.3% and 7.8% of genome, respectively. The average block length was found close to 26 kb which suggests that multiple recombination events fragmented the ancestral haplotypes into smaller sizes. Gir cattle had the largest number of runs of homozygosity (ROH) regions (1762) followed by Tharparkar (1528) and Sahiwal (1138). Without pedigree information, inbreeding coefficients estimated from ROH (F) revealed that Gir had the highest F (0.099) proposing more inbreeding rate in this population. Effective population size (N) decreased slowly over the last 60 generations and at 13 generations ago; N was estimated as 70 for all the three dairy breeds. The highest gametic phase correlation (r = 0.78) was observed for Sahiwal and Tharparkar breed pair suggesting formulation of multi-breed reference population for successful implementation of genomic selection among dairy breeds. The decline in effective population size among native Indian cattle breeds may help in formulating strategies for conservation and genetic improvement of native germplasm for future use.

Dash S ，Singh A ，Dixit SP ，Kumar A ，Behera R ... -  《-》

ddRAD sequencing based genotyping of six indigenous dairy cattle breeds of India to infer existing genetic diversity and population structure.

The present investigation aimed to identify genome wide SNPs and to carry out diversity and population structure study using ddRAD-seq based genotyping of 58 individuals of six indigenous milch cattle breeds (Bos indicus) such as Sahiwal, Gir, Rathi, Tharparkar, Red Sindhi and Kankrej of India. A high percentage of reads (94.53%) were mapped to the Bos taurus (ARS-UCD1.2) reference genome assembly. Following filtration criteria, a total of 84,027 high quality SNPs were identified across the genome of 6 cattle breeds with the highest number of SNPs observed in Gir (34,743), followed by Red Sindhi (13,092), Kankrej (12,812), Sahiwal (8956), Tharparkar (7356) and Rathi (7068). Most of these SNPs were distributed in the intronic regions (53.87%) followed by intergenic regions (34.94%) while only 1.23% were located in the exonic regions. Together with analysis of nucleotide diversity (π = 0.373), Tajima's D (D value ranging from - 0.295 to 0.214), observed heterozygosity (H ranging from 0.464 to 0.551), inbreeding coefficient (F ranging from - 0.253 to 0.0513) suggested for the presence of sufficient within breed diversity in the 6 major milch breeds of India. The phylogenetic based structuring, principal component and admixture analysis revealed genetic distinctness as well as purity of almost all of the 6 cattle breeds. Overall, our strategy has successfully identified thousands of high-quality genome wide SNPs that will further enrich the Bos indicus representation basic information about genetic diversity and structure of 6 major Indian milch cattle breeds which should have implications for better management and conservation of valuable indicine cattle diversity.

Masharing N ，Sodhi M ，Chanda D ，Singh I ，Vivek P ，Tiwari M ，Kumari P ，Mukesh M ... -  《Scientific Reports》