Indicine Breeds Research Articles

Evaluating efficiency of customized medium density INDUSCHIP for genotyping of Indicine cattle breeds

To initiate genomic selection programme for indicine cattle breeds and their crosses in India, National Dairy Development Board designed a medium-density (52K) customized chip on Illumina platform named as “INDUSCHIP”. The present study was conducted to examine the efficiency of INDUSCHIP SNP panel for genotyping indicine cattle breeds. Total of 500 animals belonging to 14 different indicine breeds were genotyped with Illumina Bovine HD chip. A subset of SNPs was taken for evaluating the performance of selected SNPs in different indicine breeds. The average minor allele frequency (MAF) was found to vary between 0.20–0.29 for different indicine breeds. However, for important milk breeds like Sahiwal, Gir, Red Sindhi and Kankrej the average MAF was found to be 0.27 and above. Mean Linkage Disequilibrium (LD) at 50–60 kbp distance was found to be around 0.21. There was considerable LD decay with increasing distance between SNPs. Around 0.06% SNPs were found to be significantly deviating from Hardy-Weinberg equilibrium. From the Principal component analysis (PCA) it was found that the first three Principal Components i.e. PC1, PC2 and PC3) could separate different indicine breeds. The present study indicated that due to the presence of highly polymorphic SNPs for the breeds of indicine origin, INDUSCHIP panel was found to be effective and informative in genotyping indicine breeds.

Introgression, admixture, and selection facilitate genetic adaptation to high-altitude environments in cattle

Domestication and subsequent selection of cattle to form breeds and biological types that can adapt to different environments partitioned ancestral genetic diversity into distinct modern lineages. Genome-wide selection particularly for adaptation to extreme environments left detectable signatures genome-wide. We used high-density genotype data for 42 cattle breeds and identified the influence of Bos grunniens and Bos javanicus on the formation of Chinese indicine breeds that led to their divergence from India-origin zebu. We also found evidence for introgression, admixture, and migration in most of the Chinese breeds. Selection signature analyses between high-altitude (≥1800 m) and low-altitude adapted breeds (<1500 m) revealed candidate genes (ACSS2, ALDOC, EPAS1, EGLN1, NUCB2) and pathways that are putatively involved in hypoxia adaptation. Immunohistochemical, real-time PCR and CRISPR/cas9 ACSS2-knockout analyses suggest that the up-regulation of ACSS2 expression in the liver promotes the metabolic adaptation of cells to hypoxia via the hypoxia-inducible factor pathway. High altitude adaptation involved the introgression of alleles from high-altitude adapted yaks into Chinese Bos taurus taurus prior to their formation into recognized breeds and followed by selection. In addition to selection, adaptation to high altitude environments has been facilitated by admixture and introgression with locally adapted cattle populations.

A conserved haplotype in Wagyu cattle contains RAB4A whose encoded protein regulates glucose trafficking in muscle and fat cells

The Wagyu breed of taurine cattle possess favourable genetics for intramuscular fat (IMF) but genomic loci associated with the trait remain under characterised. Here, we report the identification of a previously unidentified genomic region possessing a particular haplotype structure in Wagyu. Through deployment of a genome-wide haplotype detection analysis that captures regions conserved in a target population but not other populations we screened 100 individual Wagyu and contrasted them with 100 individuals from two independent comparison breeds, Charolais and Angus, using high-density SNPs. An extreme level of Wagyu conservation was assigned to a single genomic window (spanning genomic coordinates BTA28:41088-300265bp). In fact, a five-SNP region spanning 27096bp is almost perfectly conserved among the 100 Wagyu individuals assayed and partially overlaps RAB4A. Focussing in, two consecutive SNPs (genomic coordinates 236949 and 239950) are apparently fixed within the Wagyu (BB and AA respectively), but at mixed frequencies in the other two breeds. These SNPs are located in the two introns straddling exon 7. In a separate analysis using the 1000 Bulls database, we found that, coincident with exon 7 of RAB4A first allele frequencies were highest in the high IMF Japanese Native (Wagyu) breeds (0.78) and lowest in the low IMF indicine breeds (Nelore and Brahman), with intermediate marbling breeds (Angus and Charolais) assigned intermediate rankings (0.42). RAB4A is known to encode a protein that regulates intracellular trafficking of the insulin-regulated glucose transporter GLUT4. RAB4A can be considered an attractive new positional candidate for IMF development.

Small SNP panels for breed proportion estimation in Indian crossbred dairy cattle.

Reliably identifying breed proportions in crossbred cattle in smallholder farms is a crucial step to improve mating decisions and optimizing management in these systems. High‐density genotype information is able to estimate higher‐order breed proportions accurately, but, are too expensive for mass application in smallholder systems. We used high‐density genotype information (777 k SNPs) of 623 crossbred cattle from India that had Holstein‐Friesian (HFX) and/or Jersey and indigenous breeds in their ancestry to select a smaller number of SNPs for breed proportion estimation. The accuracy of estimates obtained from panels with 100–500 SNP was compared to estimates based on all SNPs. Panels were selected for highest absolute allele frequency difference between exotic dairy versus indigenous Bos indicus, or between HFX versus Jersey breeds. A step‐wise pruning approach was developed showing that and increased physical distances between markers of 8.5 Mb improved breed proportion estimation compared to a standard 1 Mb distance. A panel of 500 SNPs optimized to estimate HFX versus Jersey versus indicine ancestry was able to estimate indicine breed proportions with r 2 = .991, HFX proportions with r 2 = .979 and Jersey proportions with r 2 = .949. The number of markers was a deciding factor in estimation accuracy, together with the distribution of markers across the genome.

Genome-wide association study between copy number variation regions and carcass- and meat-quality traits in Nellore cattle

Context Indicine breeds are the main source of beef products in tropical and subtropical regions. However, genetic improvement for carcass- and meat-quality traits in zebu cattle have been limited and genomics studies concerning structural variations that influence these traits are essential. Aim The aim of this study was to perform a genome-wide association study between copy number variation regions (CNVRs) and carcass- and meat quality-traits in Nellore cattle. Methods In total, 3794 animals, males and females included, were genotyped using a 777 962 single-nucleotide polymorphism platform of BovineHD BeadChip (777k; Illumina Inc.). Of these, 1751 Nellore bulls were slaughtered at 24 months of age for further carcass beef analysis. The following traits were studied: beef tenderness, marbling, rib-eye area, backfat thickness and meat colour (lightness, redness and yellowness). The CNV detection was conducted through PennCNV software. The association analyses were performed using CNVRuler software. Key results Several identified genomic regions were linked to quantitative trait loci associated with fat deposition (FABP7) and lipid metabolism (PPARA; PLA2 family; BCHE), extracellular matrix (INS; COL10A1), contraction (SLC34A3; TRDN) and muscle development (CAPZP). The gene-enrichment analyses highlighted biological mechanisms directly related to the metabolism and synthesis of lipids and fatty acids. Conclusions The large number of potential candidate genes identified within the CNVRs, as well as the functions and pathways identified, should help better elucidate the genetic mechanisms involved in the expression of beef and carcass traits in Nellore cattle. Several CNVRs harboured genes that might have a functional impact to improve the beef and carcass traits. Implications The results obtained contribute to upgrade the sensorial and organoleptic attributes of Nellore cattle and make feasible the genetic improvement of carcass- and meat-quality traits.

A transcriptome and proteome of the tick Rhipicephalus microplus shaped by the genetic composition of its hosts and developmental stage

The cattle tick, Rhipicephalus microplus, is a monoxenous tick that co-evolved with indicine cattle on the Indian subcontinent. It causes massive damage to livestock worldwide. Cattle breeds present heritable, contrasting phenotypes of tick loads, taurine breeds carrying higher loads of the parasite than indicine breeds. Thus, a useful model is available to analyze mechanisms that determine outcomes of parasitism. We sought to gain insights on these mechanisms and used RNA sequencing and Multidimensional Protein Identification Technology (MudPIT) to generate a transcriptome from whole larvae and salivary glands from nymphs, males and females feeding on genetically susceptible and resistant bovine hosts and their corresponding proteomes. 931,698 reads were annotated into 11,676 coding sequences (CDS), which were manually curated into 116 different protein families. Male ticks presented the most diverse armamentarium of mediators of parasitism. In addition, levels of expression of many genes encoding mediators of parasitism were significantly associated with the level and stage of host immunity and/or were temporally restricted to developmental stages of the tick. These insights should assist in developing novel, sustainable technologies for tick control.

Effect of composition and size of the reference population in genotype imputation efficiency of INDUSCHIP in HF Crossbred cattle

The objective of this study was to investigate the effect of composition and size of the reference population in imputation efficiency of INDUSCHIP v2 in Indian HF crossbred cattle. Data set consisted of a total of 869 cattle from 14 Indicine breeds, 2 crossbreds (HF and Jersey crossbreds) and 2 exotic breeds (HF, Jersey) genotyped with Illumina BovineHD (Illumina, San Diego, CA) panel. Post QC, 846 animals and 449955 SNPs remained for imputation study. 3 test groups each with randomly selected 25 HFCB animals with subset genotype of INDUSCHIP v2 were created, whereas with HD genotyping data of remaining animals, 3 different categories of reference groups were created namely reference 1 (HF, Jersey, all 14 Indicine breeds, HF and Jersey crossbreds), reference 2 (HF, HF crossbred, Sahiwal, Gir and Kankrej ) and reference 3 (pure HF, Sahiwal, Gir and Kankrej). Imputation efficiency of INDUSCHIP v2 was expressed in terms of concordance rate and Dosage R2 (DR2). Reference groups 1 and 2 were found to be better than Reference group 3. Further, the size of the reference population had an impact on imputation efficiency. The concordance rate and DR2 decreased with decline about population size. However, a reference population with 280 animals was found to be sufficient to obtain a concordance rate of around 95% or more and DR2 around 0.93. More number of HF, HF crossbred, Sahiwal, Gir and Kankrej animals need to be HD genotyped and incorporated in the reference population to improve the imputation efficiency of INDUSCHIP v2.

Y-chromosome genetic diversity of Bos indicus cattle in close proximity to the centre of domestication

Y-chromosome genetic diversity in and around its domestication origin and a better understanding of indicine-specific microsatellite alleles are imperative concerns but less -targeted. We analysed Y-chromosome markers in 301 bulls representing 19 native Indian cattle (Bos indicus) and identified new alleles and haplotypes. Compared to other indicine studies, the high Y-haplotype diversity found in Indian cattle supports the hypothesis of greater genetic variability across the centre of origin decreasing along migratory routes with increasing distance. Hence, a considerable paternal genetic diversity of Indian cattle appears to have been lost in transboundary commercial indicine breeds. The Khillar and Gir are the most diversified populations where the first tends to be the well-differentiated traditional breed carrying strikingly distinct Y-lineages with typical BM861-158 bp allele, characteristics of taurine cattle, while retaining standard indicine lineages for all other markers. Geographical distribution found to be an unreliable predictor of parental variation, and Y-lineages seemed closely related to Indian breed function/utility. The comprehensive Y-chromosome information will be useful to examine the demographic expansion/spread of Bos indicus lineages from close proximity to the domestication centre across different countries worldwide and such diversity should be preserved through effective management and conservation programs.

Selection signatures in tropical cattle are enriched for promoter and coding regions and reveal missense mutations in the damage response gene HELB

BackgroundDistinct domestication events, adaptation to different climatic zones, and divergent selection in productive traits have shaped the genomic differences between taurine and indicine cattle. In this study, we assessed the impact of artificial selection and environmental adaptation by comparing whole-genome sequences from European taurine and Asian indicine breeds and from African cattle. Next, we studied the impact of divergent selection by exploiting predicted and experimental functional annotation of the bovine genome.ResultsWe identified selective sweeps in beef cattle taurine and indicine populations, including a 430-kb selective sweep on indicine cattle chromosome 5 that is located between 47,670,001 and 48,100,000 bp and spans five genes, i.e. HELB, IRAK3, ENSBTAG00000026993, GRIP1 and part of HMGA2. Regions under selection in indicine cattle display significant enrichment for promoters and coding genes. At the nucleotide level, sites that show a strong divergence in allele frequency between European taurine and Asian indicine are enriched for the same functional categories. We identified nine single nucleotide polymorphisms (SNPs) in coding regions that are fixed for different alleles between subspecies, eight of which were located within the DNA helicase B (HELB) gene. By mining information from the 1000 Bull Genomes Project, we found that HELB carries mutations that are specific to indicine cattle but also found in taurine cattle, which are known to have been subject to indicine introgression from breeds, such as N’Dama, Anatolian Red, Marchigiana, Chianina, and Piedmontese. Based on in-house genome sequences, we proved that mutations in HELB segregate independently of the copy number variation HMGA2-CNV, which is located in the same region.ConclusionsMajor genomic sequence differences between Bos taurus and Bos indicus are enriched for promoter and coding regions. We identified a 430-kb selective sweep in Asian indicine cattle located on chromosome 5, which carries SNPs that are fixed in indicine populations and located in the coding sequences of the HELB gene. HELB is involved in the response to DNA damage including exposure to ultra-violet light and is associated with reproductive traits and yearling weight in tropical cattle. Thus, HELB likely contributed to the adaptation of tropical cattle to their harsh environment.

Consequences of breed formation on patterns of genomic diversity and differentiation: the case of highly diverse peripheral Iberian cattle

BackgroundIberian primitive breeds exhibit a remarkable phenotypic diversity over a very limited geographical space. While genomic data are accumulating for most commercial cattle, it is still lacking for these primitive breeds. Whole genome data is key to understand the consequences of historic breed formation and the putative role of earlier admixture events in the observed diversity patterns.ResultsWe sequenced 48 genomes belonging to eight Iberian native breeds and found that the individual breeds are genetically very distinct with FST values ranging from 4 to 16% and have levels of nucleotide diversity similar or larger than those of their European counterparts, namely Jersey and Holstein. All eight breeds display significant gene flow or admixture from African taurine cattle and include mtDNA and Y-chromosome haplotypes from multiple origins. Furthermore, we detected a very low differentiation of chromosome X relative to autosomes within all analyzed taurine breeds, potentially reflecting male-biased gene flow.ConclusionsOur results show that an overall complex history of admixture resulted in unexpectedly high levels of genomic diversity for breeds with seemingly limited geographic ranges that are distantly located from the main domestication center for taurine cattle in the Near East. This is likely to result from a combination of trading traditions and breeding practices in Mediterranean countries. We also found that the levels of differentiation of autosomes vs sex chromosomes across all studied taurine and indicine breeds are likely to have been affected by widespread breeding practices associated with male-biased gene flow.

Genomic variants identified from whole-genome resequencing of indicine cattle breeds from Pakistan.

The primary goal of cattle genomics is the identification of genome-wide polymorphism associated with economically important traits. The bovine genome sequencing project was completed in 2009. Since then, using massively parallel sequencing technologies, a large number of Bos taurus cattle breeds have been resequenced and scanned for genome-wide polymorphisms. As a result, a substantial number of single nucleotide polymorphisms (SNPs) have been discovered across European Bos taurus genomes, whereas extremely less number of SNPs are cataloged for Bos indicus breeds. In this study, we performed whole-genome resequencing, reference-based mapping, functional annotation and gene enrichment analysis of 20 sires representing eleven important Bos indicus (indicine) breeds of Pakistan. The breeds sequenced here include: Sahiwal, Red Sindhi, Tharparkar and Cholistani (tropically adapted dairy and dual purpose breeds), Achai, Bhagnari, Dajal and Lohani (high altitude adapted dual and drought purpose breeds); Dhanni, Hisar Haryana and Gabrali (dairy and light drought purpose breeds). A total of 17.4 billion QC passed reads were produced using BGISEQ-500 next generation sequencing platform to generate 9 to 27-fold genome coverage (average ~16×) for each of the 20 sequenced sires. A total of 67,303,469 SNPs were identified, of which 3,850,365 were found novel and 1,083,842 insertions-deletions (InDels) were detected across the whole sequenced genomes (491,247 novel). Comparative analysis using coding region SNPs revealed a close relationship between the best milking indicine breeds; Red Sindhi and Sahiwal. On the other hand, Bhagnari and Tharparkar being popular for their adaptation to dry and extremely hot climates were found to share the highest number of SNPs. Functional annotation identified a total of 3,194 high-impact (disruptive) SNPs and 745 disruptive InDels (in 275 genes) that may possibly affect economically important dairy and beef traits. Functional enrichment analysis was performed and revealed that high or moderate impact variants in wingless-related integration site (Wnt) and vascular smooth muscle contraction (VSMC) signaling pathways were significantly over-represented in tropically adapted heat tolerant Pakistani-indicine breeds. On the other hand, vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1 (HIF-1) signaling pathways were found over-represented in highland adapted Pakistani-indicine breeds. Similarly, the ECM-receptor interaction and Jak-STAT signaling pathway were significantly enriched in dairy and beef purpose Pakistani-indicine cattle breeds. The Toll-like receptor signaling pathway was significantly enriched in most of the Pakistani-indicine cattle. Therefore, this study provides baseline data for further research to investigate the molecular mechanisms of major traits and to develop potential genomic markers associated with economically important breeding traits, particularly in indicine cattle.

Evaluation of two bovine SNP genotyping arrays for breed clustering and stratification analysis in well-known taurine and indicine breeds

The present study aimed to evaluate the efficiency of two Bovine SNP genotyping arrays (i.e., 50 K and HD) for breed clustering and stratification related studies in taurine and indicine breeds. The whole-genome SNP data at two densities were assembled into three datasets (A, B and C). Dataset A (N = 213) included 50 K genotypic data for five taurine (Holstein–Friesian, Guernsey, Brown Swiss, Angus and Jersey) and two indicine (Gir and Nellore) breeds. Dataset B (N = 241) included the same breeds with HD density data. Dataset C (N = 299) included 50 K SNP genotypic data for six taurine (Holstein–Friesian, Jersey, Guernsey, Brown Swiss, Angus and Hereford) and six indicine (Hariana, Kankrej, Brahman, Nellore, Sahiwal and Gir) breeds. The analysis was done using ADMIXTURE program (bioinformatics-based) and cross-validation errors and Principal Component Analysis (statistical analysis). The proportion of polymorphic markers and minor allele frequencies were assessed for each breed. The proportion of markers polymorphic was consistently higher in taurine breeds when compared with breeds from indicine group. Minor allele frequency estimates and ADMIXTURE results showed differential patterns for both the lineages. However, no significant increase in the accuracy of genomic clustering was found on moving from 50 K to HD density data.

Accuracy of genomic predictions in Gyr (Bos indicus) dairy cattle

Genomic selection may accelerate genetic progress in breeding programs of indicine breeds when compared with traditional selection methods. We present results of genomic predictions in Gyr (Bos indicus) dairy cattle of Brazil for milk yield (MY), fat yield (FY), protein yield (PY), and age at first calving using information from bulls and cows. Four different single nucleotide polymorphism (SNP) chips were studied. Additionally, the effect of the use of imputed data on genomic prediction accuracy was studied. A total of 474 bulls and 1,688 cows were genotyped with the Illumina BovineHD (HD; San Diego, CA) and BovineSNP50 (50K) chip, respectively. Genotypes of cows were imputed to HD using FImpute v2.2. After quality check of data, 496,606 markers remained. The HD markers present on the GeneSeek SGGP-20Ki (15,727; Lincoln, NE), 50K (22,152), and GeneSeek GGP-75Ki (65,018) were subset and used to assess the effect of lower SNP density on accuracy of prediction. Deregressed breeding values were used as pseudophenotypes for model training. Data were split into reference and validation to mimic a forward prediction scheme. The reference population consisted of animals whose birth year was ≤2004 and consisted of either only bulls (TR1) or a combination of bulls and dams (TR2), whereas the validation set consisted of younger bulls (born after 2004). Genomic BLUP was used to estimate genomic breeding values (GEBV) and reliability of GEBV (R2PEV) was based on the prediction error variance approach. Reliability of GEBV ranged from ∼0.46 (FY and PY) to 0.56 (MY) with TR1 and from 0.51 (PY) to 0.65 (MY) with TR2. When averaged across all traits, R2PEV were substantially higher (R2PEV of TR1 = 0.50 and TR2 = 0.57) compared with reliabilities of parent averages (0.35) computed from pedigree data and based on diagonals of the coefficient matrix (prediction error variance approach). Reliability was similar for all the 4 marker panels using either TR1 or TR2, except that imputed HD cow data set led to an inflation of reliability. Reliability of GEBV could be increased by enlarging the limited bull reference population with cow information. A reduced panel of ∼15K markers resulted in reliabilities similar to using HD markers. Reliability of GEBV could be increased by enlarging the limited bull reference population with cow information.

Whole genome sequencing of Guzerá cattle reveals genetic variants in candidate genes for production, disease resistance, and heat tolerance.

In bovines, artificial selection has produced a large number of breeds which differ in production, environmental adaptation, and health characteristics. To investigate the genetic basis of these phenotypical differences, several bovine breeds have been sequenced. Millions of new SNVs were described at every new breed sequenced, suggesting that every breed should be sequenced. Guzerat or Guzerá is an indicine breed resistant to drought and parasites that has been the base for some important breeds such as Brahman. Here, we describe the sequence of the Guzerá genome and the in silico functional analyses of intragenic breed-specific variations. Mate-paired libraries were generated using the ABI SOLiD system. Sequences were mapped to the Bos taurus reference genome (UMD 3.1) and 87% of the reference genome was covered at a 26X. Among the variants identified, 2,676,067 SNVs and 463,158 INDELs were homozygous, not found in any database searched, and may represent true differences between Guzerá and B. taurus. Functional analyses investigated with the NGS-SNP package focused on 1069 new, non-synonymous SNVs, splice-site variants (including acceptor and donor sites, and the conserved regions at both intron borders, referred to here as splice regions) and coding INDELs (NS/SS/I). These NS/SS/I map to 935 genes belonging to cell communication, environmental adaptation, signal transduction, sensory, and immune systems pathways. These pathways have been involved in phenotypes related to health, adaptation to the environment and behavior, and particularly, disease resistance and heat tolerance. Indeed, 105 of these genes are known QTLs for milk, meat and carcass, production, reproduction, and health traits. Therefore, in addition to describing new genetic variants, our approach provided groundwork for unraveling key candidate genes and mutations.

A genome-wide assessment of genetic diversity and population structure of Korean native cattle breeds.

BackgroundThe native cattle breeds are an important genetic resource for meat and milk production throughout Asia. In Asia cattle were domesticated around 10,000 years ago and in Korea cattle are being raised since 2000 B.C. There are three native breeds of cattle in Korea viz. Brown Hanwoo, Brindle Hanwoo and Jeju Black. While one of these breeds, Brown Hanwoo, is a part of a Food and Agricultural Organization and national genetic evaluation plans, others get little attention. This study is an effort to understand and provide a detailed insight into the population structure and genetic variability of the Korean cattle breeds along with other Asian breeds using various methods. In this study we report the genetic variation and structure of the Korean cattle breeds and their comparison with five other Asian cattle breeds along with a panel of animals from European taurine, African taurine and indicine cattle breeds.ResultsAsian cattle were found to be least differentiated which reflects their recent history. Amongst the Asian breeds Hainan, which is an indicine breed, had the lowest gene diversity while Yanbian had the highest followed by Mongolian and Korean cattle. Amongst the Korean breeds Brown Hanwoo had the highest diversity followed by Brindle Hanwoo and Jeju Black. The genetic diversity in Asian cattle breeds was found comparable to the European taurines and more than the African taurines and Zebu cattle. Korean cattle breed, Brown Hanwoo was consistently found to be closer to Yanbian, a Chinese cattle breed. We found low divergence and moderate levels of genetic diversity among the native Korean breeds. Indicine introgression from Hainan was seen in other Asian breeds. From Europe, Limousin, Holstein and Hereford introgression was found in Asian breeds.ConclusionsIn this study we provide a genome-wide insight into the genetic history of the native cattle breeds of Korea. The outcomes of this study will help in prioritization and designing of the conservation plans.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0444-8) contains supplementary material, which is available to authorized users.

Diversity and population-genetic properties of copy number variations and multicopy genes in cattle.

The diversity and population genetics of copy number variation (CNV) in domesticated animals are not well understood. In this study, we analysed 75 genomes of major taurine and indicine cattle breeds (including Angus, Brahman, Gir, Holstein, Jersey, Limousin, Nelore, and Romagnola), sequenced to 11-fold coverage to identify 1,853 non-redundant CNV regions. Supported by high validation rates in array comparative genomic hybridization (CGH) and qPCR experiments, these CNV regions accounted for 3.1% (87.5 Mb) of the cattle reference genome, representing a significant increase over previous estimates of the area of the genome that is copy number variable (∼2%). Further population genetics and evolutionary genomics analyses based on these CNVs revealed the population structures of the cattle taurine and indicine breeds and uncovered potential diversely selected CNVs near important functional genes, including AOX1, ASZ1, GAT, GLYAT, and KRTAP9-1. Additionally, 121 CNV gene regions were found to be either breed specific or differentially variable across breeds, such as RICTOR in dairy breeds and PNPLA3 in beef breeds. In contrast, clusters of the PRP and PAG genes were found to be duplicated in all sequenced animals, suggesting that subfunctionalization, neofunctionalization, or overdominance play roles in diversifying those fertility-related genes. These CNV results provide a new glimpse into the diverse selection histories of cattle breeds and a basis for correlating structural variation with complex traits in the future.

Length and density of filiform tongue papillae: differences between tick-susceptible and resistant cattle may affect tick loads.

BackgroundIndicine breeds of bovines are highly resistant and taurine breeds are susceptible to the cattle tick, Rhipicephalus microplus, a species which causes great damage to livestock. Animals use their tongues for self-grooming, an important behavior for ridding themselves of ectoparasites. However, the role of tongue morphology, notably the filiform papillae, in this process is not known.FindingsThis study compared features of the filiform papillae of tongues in eight Nelores (indicine breed) and eight Holsteins and two Brown Swiss (taurine breeds) and verified how they associate with tick loads. Biopsies were taken from identical positions of tongues and measured by scanning electron microscopy. One-way analysis of variance detected significant differences between morphological features of tongues from indicine and taurine breeds: Nelores had longer papillae (mean of 2.3 mm ± 0.029 SD; P < 0.001), and more papillae per cm2 (mean of 25.2 papillae ± 1.92 SD; P < 0.05) than European bovines (means of, respectively, 1.8 mm ± 0.027 SD and 20.9 ± 0.74 SD papillae per cm2). After infestations with equal numbers of larvae, loads of adult ticks were inversely correlated with length of papillae and directly correlated with distances between the apices of papillae (P = 0.014; r = −0.566 and P = 0.018; r = 0.567, Pearson product momentum correlation, respectively).ConclusionsSpacing between papillae is smaller in Nelores, thus their tongues may be rougher and, consequently, more effective in removing tick larvae during self-grooming, explaining the greater resistance to ticks among Zebu breeds of cattle.

Genetic analysis of Thai cattle reveals a Southeast Asian indicine ancestry.

Cattle commonly raised in Thailand have characteristics of Bos indicus (zebu). We do not know when or how cattle domestication in Thailand occurred, and so questions remain regarding their origins and relationships to other breeds. We obtained genome-wide SNP genotypic data of 28 bovine individuals sampled from four regions: North (Kho-Khaolampoon), Northeast (Kho-Isaan), Central (Kho-Lan) and South (Kho-Chon) Thailand. These regional varieties have distinctive traits suggestive of breed-like genetic variations. From these data, we confirmed that all four Thai varieties are Bos indicus and that they are distinct from other indicine breeds. Among these Thai cattle, a distinctive ancestry pattern is apparent, which is the purest within Kho-Chon individuals. This ancestral component is only present outside of Thailand among other indicine breeds in Southeast Asia. From this pattern, we conclude that a unique Bos indicus ancestor originated in Southeast Asia, and native Kho-Chon Thai cattle retain the signal of this ancestry with limited admixture of other bovine ancestors.

Strategies for single nucleotide polymorphism (SNP) genotyping to enhance genotype imputation in Gyr (Bos indicus) dairy cattle: Comparison of commercially available SNP chips

Genotype imputation is widely used as a cost-effective strategy in genomic evaluation of cattle. Key determinants of imputation accuracies, such as linkage disequilibrium patterns, marker densities, and ascertainment bias, differ between Bos indicus and Bos taurus breeds. Consequently, there is a need to investigate effectiveness of genotype imputation in indicine breeds. Thus, the objective of the study was to investigate strategies and factors affecting the accuracy of genotype imputation in Gyr (Bos indicus) dairy cattle. Four imputation scenarios were studied using 471 sires and 1,644 dams genotyped on Illumina BovineHD (HD-777K; San Diego, CA) and BovineSNP50 (50K) chips, respectively. Scenarios were based on which reference high-density single nucleotide polymorphism (SNP) panel (HDP) should be adopted [HD-777K, 50K, and GeneSeek GGP-75Ki (Lincoln, NE)]. Depending on the scenario, validation animals had their genotypes masked for one of the lower-density panels: Illumina (3K, 7K, and 50K) and GeneSeek (SGGP-20Ki and GGP-75Ki). We randomly selected 171 sires as reference and 300 as validation for all the scenarios. Additionally, all sires were used as reference and the 1,644 dams were imputed for validation. Genotypes of 98 individuals with 4 and more offspring were completely masked and imputed. Imputation algorithms FImpute and Beagle v3.3 and v4 were used. Imputation accuracies were measured using the correlation and allelic correct rate. FImpute resulted in highest accuracies, whereas Beagle 3.3 gave the least-accurate imputations. Accuracies evaluated as correlation (allelic correct rate) ranged from 0.910 (0.942) to 0.961 (0.974) using 50K as HDP and with 3K (7K) as low-density panels. With GGP-75Ki as HDP, accuracies were moderate for 3K, 7K, and 50K, but high for SGGP-20Ki. The use of HD-777K as HDP resulted in accuracies of 0.888 (3K), 0.941 (7K), 0.980 (SGGP-20Ki), 0.982 (50K), and 0.993 (GGP-75Ki). Ungenotyped individuals were imputed with an average accuracy of 0.970. The average top 5 kinship coefficients between reference and imputed individuals was a strong predictor of imputation accuracy. FImpute was faster and used less memory than Beagle v4. Beagle v4 outperformed Beagle v3.3 in accuracy and speed of computation. A genotyping strategy that uses the HD-777K SNP chip as a reference panel and SGGP-20Ki as the lower-density SNP panel should be adopted as accuracy was high and similar to that of the 50K. However, the effect of using imputed HD-777K genotypes from the SGGP-20Ki on genomic evaluation is yet to be studied.

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.