Genomic clues of the evolutionary history of Bos indicus cattle

Genetic advancements and future directions in ruminant livestock breeding: from reference genomes to multiomics innovations

Ruminant livestock provide a rich source of products, such as meat, milk, and wool, and play a critical role in global food security and nutrition. Over the past few decades, genomic studies of ruminant livestock have provided valuable insights into their domestication and the genetic basis of economically important traits, facilitating the breeding of elite varieties. In this review, we summarize the main advancements for domestic ruminants in reference genome assemblies, population genomics, and the identification of functional genes or variants for phenotypic traits. These traits include meat and carcass quality, reproduction, milk production, feed efficiency, wool and cashmere yield, horn development, tail type, coat color, environmental adaptation, and disease resistance. Functional genomic research is entering a new era with the advancements of graphical pangenomics and telomere-to-telomere (T2T) gap-free genome assembly. These advancements promise to improve our understanding of domestication and the molecular mechanisms underlying economically important traits in ruminant livestock. Finally, we provide new perspectives and future directions for genomic research on ruminant genomes. We suggest how ever-increasing multiomics datasets will facilitate future studies and molecular breeding in livestock, including the potential to uncover novel genetic mechanisms underlying phenotypic traits, to enable more accurate genomic prediction models, and to accelerate genetic improvement programs.

Early to Mid-Holocene land use transitions in South Asia: A new archaeological synthesis of potential human impacts

While it is clear that current human impact on the earth system is unprecedented in scope and scale, much less is known about the long-term histories of human land use and their effects on vegetation, carbon cycling, and other factors relevant to climate change. Current debates over the possible importance of human activities since the mid second millennium CE cannot be effectively resolved without evidence-based reconstructions of past land use and its consequences. The goal of the PAGES LandCover 6K working group is to reconstruct human land use and land cover over the past 12,000 years. In this paper, we present the first large-scale synthesis of archaeological evidence for human land use in South Asia at 12 and 6kya, a critical period for the transition to agriculture, arguably one of the land use transitions most consequential in terms of human impact on the Earth system. Perhaps the most important narrative we can pick out is that while there are some shifts in land use across these time windows, hunter-gatherer-fisher-foraging remained the dominant land use, and within this there was a mosaic of strategies exploiting diverse and complex landscapes and ecologies. This is not necessarily a new conclusion-it is not new to state that South Asia is comprised of many niches, but demonstrating the deep time history of how people have adapted to these and adapted them is an important step for modelling the impacts of human populations and thinking about their footprints in a longue-durée perspective. Despite the new development of food production between the early and mid-Holocene by overall area foraging life ways continued as the dominant land use practice into the 6kya time window. The development of agriculture and food production was not unimportant-it is the beginning of a land use that eventually comes to dominate the sub-continent, but at 6kya agriculture was restricted to specific contexts. Across 12kya to 6kya and different land uses, the use of mosaic ecologies, diverse strategies and the importance of water as a resource stand out as shared themes.

Mitogenome diversity and evolution of Bos indicus cattle in India

Mitochondrial DNA has been widely utilized as a valuable tool for studying the evolutionary and demographic history both within and between different livestock speciesover the past three decades. Evaluation of the evolutionary history, population structure and genetic diversity is imperative for their productivity, ecosystem services, and breeding and conservation strategies for effective management. The present study included complete mitogenome of 78 cattle, out of which 33 samples belonged to 6 Bos indicus breeds of India. Mitogenome diversity of zebu cattle within population (π- nucleotide, haplotype diversity) was estimated using DnaSP v6 software and between populations (FST ratio, AMOVA analysis) was estimated using Arlequin 3.5.2.2. Ladakhi breed showed maximum (π = 0.00645) while Gir (π = 0.00042) and Tharparkar (π = 0.00053) showed minimum diversity. The diversity between the breeds of Indian cattle was 16.34 %. There were 13 and 14 haplotypes in each of I1 and I2 halogroups respectively suggesting that the divergence of Bos indicus haplotypes likely occurred within the Indian subcontinent. The Bos indicus and Bos taurus cattle lineages separated approximately 0.75 million years ago. The divergence pattern observed in zebu cattle highlighted the probability of a distinct ancestor and supported notion of independent divergence of Bos indicus.

Selection Increases Mitonuclear DNA Discordance but Reconciles Incompatibility in African Cattle

Mitochondrial function relies on the coordinated interactions between genes in the mitochondrial DNA and nuclear genomes. Imperfect interactions following mitonuclear incompatibility may lead to reduced fitness. Mitochondrial DNA introgressions across species and populations are common and well documented. Various strategies may be expected to reconcile mitonuclear incompatibility in hybrids or admixed individuals. African admixed cattle (Bos taurus × B. indicus) show sex-biased admixture, with taurine (B. taurus) mitochondrial DNA and a nuclear genome predominantly of humped zebu (B. indicus). Here, we leveraged local ancestry inference approaches to identify the ancestry and distribution patterns of nuclear functional genes associated with the mitochondrial oxidative phosphorylation process in the genomes of African admixed cattle. We show that most of the nuclear genes involved in mitonuclear interactions are under selection and of humped zebu ancestry. Variations in mitochondrial DNA copy number may have contributed to the recovery of optimal mitochondrial function following admixture with the regulation of gene expression, alleviating or nullifying mitochondrial dysfunction. Interestingly, some nuclear mitochondrial genes with enrichment in taurine ancestry may have originated from ancient African aurochs (B. primigenius africanus) introgression. They may have contributed to the local adaptation of African cattle to pathogen burdens. Our study provides further support and new evidence showing that the successful settlement of cattle across the continent was a complex mechanism involving adaptive introgression, mitochondrial DNA copy number variation, regulation of gene expression, and selection of ancestral mitochondria-related genes.

Whole genome re-sequencing reveals high altitude adaptation signatures and admixture in Ladakhi cattle

Ladakhi cattle, native to the high-altitude region of Ladakh in northern India (ranging from 3,000 to 5,000 m above sea level), have evolved unique genetic adaptations to thrive in harsh environmental conditions, such as hypoxia, extreme cold, and low humidity. This study explored the genome of Ladakhi cattle to investigate genetic structure, selection signatures, and adaptive mechanisms. Whole genome sequencing reads, generated on Illumina NovaSeq 6000 platform, were aligned to the Bos taurus reference genome with BWA-MEM. SNPs were identified and filtered using GATK and bcftools, and functionally annotated with SnpEff. For population genomic analysis, PCA and admixture modeling assessed genetic structure, while Neighbor-Joining trees, LD decay, nucleotide diversity (π), and FST evaluated phylogenetic relationships and genetic variation. Selective sweeps were detected using RAiSD, and gene-set enrichment and protein-protein interaction analyses were conducted to explore functional pathways related to adaptation. The study revealed 3,759,279 unique SNPs and demonstrated that Ladakhi cattle form a distinct genetic cluster with an estimated admixture of 68 % Bos indicus and 32 % Bos taurus ancestry. Key findings include rapid linkage disequilibrium decay, low inbreeding level, and the identification of selection signatures and genes associated with hypoxia response, energy metabolism, and cold adaptation. Mean nucleotide diversity (π, 0.0037) and FST values indicated moderate genetic differentiation from other breeds. The analysis highlighted selection signatures for genes like HIF1A, ENO4, ANGPT1, EPO, NOS3, MAPK3, HMOX1, BCL2,CAMK2D, MTOR, AKT2,PIK3CB, and MAP2K1, among others, including various keratin and heat shock proteins. The interaction between genes associated with hypoxia signaling (HIF-1) and other enriched pathways such as PI3K, mTOR, NFκB, ERK, and ER stress, reveals a complex mechanism for managing hypoxic stress in Ladakhi cattle. These findings offer valuable insights for breeding programs aimed at enhancing livestock resilience in extreme environments and enhance understanding of mammalian adaptation to high-altitude conditions.

Genome-wide local ancestry and the functional consequences of admixture in African and European cattle populations

Bos taurus (taurine) and Bos indicus (indicine) cattle diverged at least 150,000 years ago and, since that time, substantial genomic differences have evolved between the two lineages. During the last two millennia, genetic exchange in Africa has resulted in a complex tapestry of taurine-indicine ancestry, with most cattle populations exhibiting varying levels of admixture. Similarly, there are several Southern European cattle populations that also show evidence for historical gene flow from indicine cattle, the highest levels of which are found in the Central Italian White breeds. Here we use two different software tools (MOSAIC and ELAI) for local ancestry inference (LAI) with genome-wide high- and low-density SNP array data sets in hybrid African and residually admixed Southern European cattle populations and obtained broadly similar results despite critical differences in the two LAI methodologies used. Our analyses identified genomic regions with elevated levels of retained or introgressed ancestry from the African taurine, European taurine, and Asian indicine lineages. Functional enrichment of genes underlying these ancestry peaks highlighted biological processes relating to immunobiology and olfaction, some of which may relate to differing susceptibilities to infectious diseases, including bovine tuberculosis, East Coast fever, and tropical theileriosis. Notably, for retained African taurine ancestry in admixed trypanotolerant cattle we observed enrichment of genes associated with haemoglobin and oxygen transport. This may reflect positive selection of genomic variants that enhance control of severe anaemia, a debilitating feature of trypanosomiasis disease, which severely constrains cattle agriculture across much of sub-Saharan Africa.

Complete Genomic Landscape Reveals Hidden Evolutionary History and Selection Signature in Asian Water Buffaloes (Bubalus bubalis)

To identify the genetic determinants of domestication and productivity of Asian water buffaloes (Bubalus bubalis), 470 genomes of domesticated river and swamp buffaloes along with their putative ancestors, the wild water buffaloes (Bubalus arnee) are sequenced and integrated. The swamp buffaloes inherit the morphology of the wild buffaloes. In contrast, most river buffaloes are unique in their morphology, but their genomes cluster with the wild buffaloes. The levels of genomic diversity in Italian river and Indonesian swamp buffaloes decrease at opposite extremes of their distribution range. Purifying selection prevented the accumulation of harmful loss-of-function variants in the Indonesian buffaloes. Genes that evolved rapidly (e.g., GKAP1) following differential selections in the river and swamp buffaloes are involved in their reproduction. Genes related to milk production (e.g., CSN2) and coat color (e.g., MC1R) underwent strong selections in the dairy river buffaloes via soft and hard selective sweeps, respectively. The selective sweeps and single-cell RNA-seq data revealed the luminal cells as the key cell type in response to artificial selection for milk production of the dairy buffaloes. These findings show how artificial selection has been driving the evolutionary divergence and genetic differentiation in morphology and productivity of Asian water buffaloes.

Tailoring Genomic Selection for Bos taurus indicus: A Comprehensive Review of SNP Arrays and Reference Genomes

BACKGROUND

Advances in SNP arrays and reference genome assemblies have significantly transformed cattle genomics, particularly for Bos taurus indicus (Zebu cattle). Many commercial SNP arrays were originally designed for Bos taurus taurus, leading to ascertainment bias and the exclusion of crucial SNPs specific to Zebu populations. This review assesses progress in SNP array and reference genome development, with a focus on efforts tailored to Zebu populations and their impact on genomic selection and breeding efficiency.

METHODS

We reviewed the relevant literature on the development of SNP arrays, reference genome assemblies, and SNP genotyping techniques used for Zebu cattle. Emphasis was placed on SNP arrays specifically designed for Zebu breeds, evaluating their contributions to genomic evaluations and identifying limitations in prediction accuracy.

RESULTS

Recent advancements, such as GeneSeek's low- and high-density SNP panels, have aimed to reduce ascertainment bias and include key SNPs for Zebu populations by providing breed-specific panels. These panels have been instrumental in identifying genomic regions associated with economically important traits in Nellore cattle. Studies show that tailored SNP arrays and breed-specific reference genomes can enhance genetic diversity assessment and improve genomic predictions, supporting more effective breeding programs for Zebu cattle.

CONCLUSIONS

Improved SNP arrays and breed-specific reference genomes are crucial for accurate genomic selection in Zebu cattle. Future efforts should prioritize expanding de novo genome assemblies, reducing ascertainment bias, and developing cost-effective genotyping solutions tailored to Zebu populations. Targeted genomic tools will ultimately enable more efficient breeding practices and enhance genomic selection for economically important traits in B. t. indicus cattle.

Temperature adaptation patterns in Chinese cattle revealed by TRPM2 gene mutation analysis

Cattle are sensitive to temperature fluctuations but adapt well to inclement weather conditions. When environmental temperatures exceed specific thresholds, heat stress becomes a critical concern for cattle. The TRPM2 gene, which resides on cattle chromosome 1 encodes a TRP channel protein, holding a unique capacity to sense temperature changes and facilitate rapid response to avoid heat stress. Here, we utilized the Bovine Genome Variation Database (BGVD) (http://animal.omics.pro/code/index.php/BosVar), and identified a missense mutation site, c.805A > G: p. Met269Val (rs527146862), within the TRPM2 gene. To elucidate the functional assessment of this mutation in temperature adaptation attributes of Chinese cattle, we genotyped 407 samples from 20 distinct breeds representing diverse climatic zones across China. The association analysis incorporates three temperature parameters and revealed compelling insights in terms of allele frequency. Interestingly, the prevalence of the wild-type allele A was notably higher among northern cattle breeds and this trend diminished gradually as observed in southern cattle populations. Conversely, the mutant-type allele G demonstrated a contrasting trend. Moreover, southern cattle exhibited markedly higher frequencies of GG and GA genotypes (P < 0.01). The presence of heterozygous and homozygous mutations appears to confer an enhanced capacity for adaptation to elevated temperatures. These results provide unequivocal correlation evidence between TRPM2 genotypes (AA, GA, GG) and environmental temperature parameters and comprehend the genetic mechanisms governing temperature adaptation in cattle. This provides valuable insights for strategic breed selection across diverse climatic regions, thereby aiding livestock production amid evolving climate challenges.

Insights into trait-association of selection signatures and adaptive eQTL in indigenous African cattle

BACKGROUND

African cattle represent a unique resource of genetic diversity in response to adaptation to numerous environmental challenges. Characterising the genetic landscape of indigenous African cattle and identifying genomic regions and genes of functional importance can contribute to targeted breeding and tackle the loss of genetic diversity. However, pinpointing the adaptive variant and determining underlying functional mechanisms of adaptation remains challenging.

RESULTS

In this study, we use selection signatures from whole-genome sequence data of eight indigenous African cattle breeds in combination with gene expression and quantitative trait loci (QTL) databases to characterise genomic targets of artificial selection and environmental adaptation and to identify the underlying functional candidate genes. In general, the trait-association analyses of selection signatures suggest the innate and adaptive immune system and production traits as important selection targets. For example, a large genomic region, with selection signatures identified for all breeds except N'Dama, was located on BTA27, including multiple defensin DEFB coding-genes. Out of 22 analysed tissues, genes under putative selection were significantly enriched for those overexpressed in adipose tissue, blood, lung, testis and uterus. Our results further suggest that cis-eQTL are themselves selection targets; for most tissues, we found a positive correlation between allele frequency differences and cis-eQTL effect size, suggesting that positive selection acts directly on regulatory variants.

CONCLUSIONS

By combining selection signatures with information on gene expression and QTL, we were able to reveal compelling candidate selection targets that did not stand out from selection signature results alone (e.g. GIMAP8 for tick resistance and NDUFS3 for heat adaptation). Insights from this study will help to inform breeding and maintain diversity of locally adapted, and hence important, breeds.

Resistance of zebu cattle (Bos indicus) to colonization by major ruminant hoof pathogens

Zebu cattle (Bos indicus) is reported to be more resistant towards harmful environmental factors than taurine cattle (Bos taurus). A few hundred zebu cattle are kept in Switzerland and in contrast to the Swiss indigenous breeds, infectious hoof disease in zebu is not observed. Therefore, we compared the prevalence of three ruminant hoof pathogens in zebu and taurine cattle. These included Treponema spp., Fusobacterium necrophorum and Dichelobacter nodosus which are associated with bovine digital dermatitis (BDD), different bovine hoof diseases and ovine footrot, respectively. Interdigital swabs and punch biopsies from hind feet of slaughter animals were tested for the three pathogens by PCR. Sixty zebu from eight farms were compared to a convenience sample of 20 taurine cattle from 17 farms. Treponema spp. associated with BDD were not detected in zebu while 23 % of animals and 50 % of farms were positive for benign D. nodosus, with results indicating environmental contamination rather than colonization. Taurine cattle showed 35 % of animals and 41 % of farms positive for T. phagedenis while 90 % of animals and 94 % of farms were colonized by D. nodosus as indicated by a 500-fold higher bacterial load than in zebu. The difference in prevalence of the two pathogens between zebu and taurine cattle was highly significant. F. necrophorum was as well only detected in taurine cattle with values of 15 % of animals and 17.7 % of farms, being significantly different at the animal level. Furthermore, genetic analysis of Swiss zebu indicates high genomic diversity and clear separation from taurine cattle. This is the first evidence that zebu show resistance towards colonization by bacterial hoof pathogens in contrast to taurine cattle.

Whole-genome resequencing deciphers patterns of genetic diversity, phylogeny, and evolutionary dynamics in Kashmir cattle

Kashmir cattle, which were kept by local pastoralists for centuries, are exceptionally resilient and adaptive to harsh environments. Despite its significance, the genomic characteristics of this cattle breed remain elusive. This study utilized whole genome sequences of Kashmir cattle (n = 20; newly sequenced) alongside published whole genomes of 32 distinct breeds and seven core cattle populations (n = 135). The analysis identified ~25.87 million biallelic single nucleotide polymorphisms in Kashmir cattle, predominantly in intergenic and intron regions. Population structure analyses revealed distinct clustering patterns of Kashmir cattle with proximity to the South Asian, African and Chinese indicine cattle populations. Genetic diversity analysis of Kashmir cattle demonstrated lower inbreeding and greater nucleotide diversity than analyzed global breeds. Homozygosity runs indicated less consanguineous mating in Kashmir cattle compared with European taurine breeds. Furthermore, six selection sweep detection methods were used within Kashmir cattle and other cattle populations to identify genes associated with vital traits, including immunity (BOLA-DQA5, BOLA-DQB, TNFAIP8L, FCRL4, AOAH, HIF1AN, FBXL3, MPEG1, CDC40, etc.), reproduction (GOLGA4, BRWD1, OSBP2, LEO1 ADCY5, etc.), growth (ADPRHL1, NRG2, TCF12, TMOD4, GBP4, IGF2, RSPO3, SCD, etc.), milk composition (MRPS30 and CSF1) and high-altitude adaptation (EDNRA, ITPR2, AGBL4 and SCG3). These findings provide essential genetic insights into the characteristics and establish the foundation for the scientific conservation and utilization of Kashmir cattle breed.

Identification of Heilongjiang crossbred beef cattle pedigrees and reveals functional genes related to economic traits based on whole-genome SNP data

Introduction: To enhance the beef cattle industry, Heilongjiang Province has developed a new Crossbred beef cattle variety through crossbreeding with exotic commercial breeds. This new variety exhibits relatively excellent meat quality, and efficient reproductive performance, catering to market demands. Method: This study employed whole genome resequencing technology to analyze the genetic pedigree and diversity of 19 Heilongjiang Crossbred beef cattle, alongside 59 published genomes from East Asian, Eurasian, and European taurine cattle as controls. In addition, genes related to production traits were also searched by identifying Runs of Homozygosity (ROH) islands and important fragments from ancestors. Results: A total of 14,427,729 biallelic SNPs were discovered, with the majority located in intergenic and intron regions and a small percentage in exon regions, impacting protein function. Population genetic analyses including Principal Component Analysis (PCA), Neighbor-Joining (NJ) tree, and ADMIXTURE identified Angus, Holstein, and Mishima as the main ancestors of Crossbred beef cattle. In genetic diversity analysis, nucleotide diversity, linkage disequilibrium, and inbreeding coefficient analysis reveal that the genetic diversity of Crossbred beef cattle is at a moderate level, and a higher inbreeding coefficient indicates the need for careful breeding management. In addition, some genes related to economic traits are identified through the identification of Runs of Homozygosity (ROH) islands and important fragments from ancestors. Conclusion: This comprehensive genomic characterization supports the targeted improvement of economically important traits in Crossbred beef cattle, facilitating advanced breeding strategies.

Trophic rewilding as a restoration approach under emerging novel biosphere conditions

Rewilding is a restoration approach that aims to promote self-regulating complex ecosystems by restoring non-human ecological processes while reducing human control and pressures. Rewilding is forward-looking in that it aims to enhance functionality for biodiversity, accepting and indeed promoting the dynamic nature of ecosystems, rather than fixating on static composition or structure. Rewilding is thus especially relevant in our epoch of increasingly novel biosphere conditions, driven by strong human-induced global change. Here, we explore this hypothesis in the context of trophic rewilding - the restoration of trophic complexity mediated by wild, large-bodied animals, known as 'megafauna'. This focus reflects the strong ecological impacts of large-bodied animals, their widespread loss during the last 50,000 years and their high diversity and ubiquity in the preceding 50 million years. Restoring abundant, diverse, wild-living megafauna is expected to promote vegetation heterogeneity, seed dispersal, nutrient cycling and biotic microhabitats. These are fundamental drivers of biodiversity and ecosystem function and are likely to gain importance for maintaining a biodiverse biosphere under increasingly novel ecological conditions. Non-native megafauna species may contribute to these effects as ecological surrogates of extinct species or by promoting ecological functionality within novel assemblages. Trophic rewilding has strong upscaling potential via population growth and expansion of wild fauna. It is likely to facilitate biotic adaptation to changing climatic conditions and resilience to ecosystem collapse, and to curb some negative impacts of globalization, notably the dominance of invasive alien plants. Finally, we discuss the complexities of realizing the biodiversity benefits that trophic rewilding offers under novel biosphere conditions in a heavily populated world.

Genome-wide mining of diversity and evolutionary signatures revealed selective hotspots in Indian Sahiwal cattle

The Sahiwal cattle breed is the best indigenous dairy cattle breed, and it plays a pivotal role in the Indian dairy industry. This is due to its exceptional milk-producing potential, adaptability to local tropical conditions, and its resilience to ticks and diseases. The study aimed to identify selective sweeps and estimate intrapopulation genetic diversity parameters in Sahiwal cattle using ddRAD sequencing-based genotyping data from 82 individuals. After applying filtering criteria, 78,193 high-quality SNPs remained for further analysis. The population exhibited an average minor allele frequency of 0.221 ± 0.119. Genetic diversity metrics, including observed (0.597 ± 0.196) and expected heterozygosity (0.433 ± 0.096), nucleotide diversity (0.327 ± 0.114), the proportion of polymorphic SNPs (0.726), and allelic richness (1.323 ± 0.134), indicated ample genomic diversity within the breed. Furthermore, an effective population size of 74 was observed in the most recent generation. The overall mean linkage disequilibrium (r2) for pairwise SNPs was 0.269 ± 0.057. Moreover, a greater proportion of short Runs of Homozygosity (ROH) segments were observed suggesting that there may be low levels of recent inbreeding in this population. The genomic inbreeding coefficients, computed using different inbreeding estimates (FHOM, FUNI, FROH, and FGROM), ranged from -0.0289 to 0.0725. Subsequently, we found 146 regions undergoing selective sweeps using five distinct statistical tests: Tajima's D, CLR, |iHS|, |iHH12|, and ROH. These regions, located in non-overlapping 500 kb windows, were mapped and revealed various protein-coding genes associated with enhanced immune systems and disease resistance (IFNL3, IRF8, BLK), as well as production traits (NRXN1, PLCE1, GHR). Notably, we identified interleukin 2 (IL2) on Chr17: 35217075-35223276 as a gene linked to tick resistance and uncovered a cluster of genes (HSPA8, UBASH3B, ADAMTS18, CRTAM) associated with heat stress. These findings indicate the evolutionary impact of natural and artificial selection on the environmental adaptation of the Sahiwal cattle population.

Population diversity, admixture, and demographic trend of the Sumba Ongole cattle based on genomic data

OBJECTIVE

Sumba Ongole (SO) cattle are valuable breed due to their important role in the development of Indonesian cattle. Despite rapid advances in molecular technology, no genomic studies on SO cattle have been conducted to date. The aim of this study is to provide genomic profile related to the population diversity, admixture, and demographic trends of SO cattle.

METHODS

Genomic information was gathered from 79 SO cattle using the Illumina Bovine SNP50 v3 Beadchip, and for comparative purposes, additional genotypes from 209 cattle populations worldwide were included. The expected and observed heterozygosity, inbreeding coefficient, pairwise fixation indices between-population, and Nei's genetic distance were examined. Multidimensional scaling, admixture, and treemix analyses were used to investigate the population structure. Based on linkage disequilibrium and effective population size calculations, the demographic trend was observed.

RESULTS

The findings indicated that the genetic diversity of SO cattle was similar to that of other indicine breeds. SO cattle were genetically related to indicines but not to taurines or Bali cattle. The study further confirmed the close relationship between SO, Ongole, and Nellore cattle. Additionally, a small portion of the Ongole mixture were identified dominant in the SO population at the moment. The study also discovered that SO and Bali cattle (Bos javanicus) could have been ancestors in the development of Ongole Grade cattle, which corresponds to the documented history of Ongolization. Our finding indicate that SO cattle have maintained stability and possess unique traits separate from their ancestors.

CONCLUSION

In conclusion, the genetic diversity of the SO cattle has been conserved as a result of the growing significance of the present demographic trend. Consistent endeavors are necessary to uphold the fitness of the breed.

Mapping restricted introgression across the genomes of admixed indigenous African cattle breeds

BACKGROUND

The genomes of indigenous African cattle are composed of components with Middle Eastern (taurine) and South Asian (indicine) origins, providing a valuable model to study hybridization and to identify genetic barriers to gene flow. In this study, we analysed indigenous African cattle breeds as models of hybrid zones, considering taurine and indicine samples as ancestors. In a genomic cline analysis of whole-genome sequence data, we considered over 8 million variants from 144 animals, which allows for fine-mapping of potential genomic incompatibilities at high resolution across the genome.

RESULTS

We identified several thousand variants that had significantly steep clines ('SCV') across the whole genome, indicating restricted introgression. Some of the SCV were clustered into extended regions, with the longest on chromosome 7, spanning 725 kb and including 27 genes. We found that variants with a high phenotypic impact (e.g. indels, intra-genic and missense variants) likely represent greater genetic barriers to gene flow. Furthermore, our findings provide evidence that a large proportion of breed differentiation in African cattle could be linked to genomic incompatibilities and reproductive isolation. Functional evaluation of genes with SCV suggest that mitonuclear incompatibilities and genes associated with fitness (e.g. resistance to paratuberculosis) could account for restricted gene flow in indigenous African cattle.

CONCLUSIONS

To our knowledge, this is the first time genomic cline analysis has been applied to identify restricted introgression in the genomes of indigenous African cattle and the results provide extended insights into mechanisms (e.g. genomic incompatibilities) contributing to hybrid differentiation. These results have important implications for our understanding of genetic incompatibilities and reproductive isolation and provide important insights into the impact of cross-breeding cattle with the aim of producing offspring that are both hardy and productive.

Comparison between indicine and taurine cattle DNA methylation reveals epigenetic variation associated to differences in morphological adaptive traits

Indicine and taurine subspecies present distinct morphological traits as a consequence of environmental adaptation and artificial selection. Although the two subspecies have been characterized and compared at genome-wide level and at specific loci, their epigenetic diversity has not yet been explored. In this work, Reduced Representation Bisulphite Sequencing (RRBS) profiling of the taurine Angus (A) and indicine Nellore (N) cattle breeds was applied to identify methylation differences between the two subspecies. Genotyping by sequencing (GBS) of the same animals was performed to detect single nucleotide polymorphisms (SNPs) at cytosines in CpG dinucleotides and remove them from the differential methylation analysis. A total of 660,845 methylated cytosines were identified within the CpG context (CpGs) across the 10 animals sequenced (5 N and 5 A). A total of 25,765 of these were differentially methylated (DMCs). Most DMCs clustered in CpG stretches nearby genes involved in cellular and anatomical structure morphogenesis. Also, sequences flanking DMC were enriched in SNPs compared to all other CpGs, either methylated or unmethylated in the two subspecies. Our data suggest a contribution of epigenetics to the regulation and divergence of anatomical morphogenesis in the two subspecies relevant for cattle evolution and sub-species differentiation and adaptation.

Inference of Admixture Origins in Indigenous African Cattle

Present-day African cattle retain a unique genetic profile composed of a mixture of the Bos taurus and Bos indicus populations introduced into the continent at different time periods. However, details of the admixture history and the exact origins of the source populations remain obscure. Here, we infer the source of admixture in the earliest domestic cattle in Africa, African taurine. We detect a significant contribution (up to ∼20%) from a basal taurine lineage, which might represent the now-extinct African aurochs. In addition, we show that the indicine ancestry of African cattle, although most closely related to so-far sampled North Indian indicine breeds, has a small amount of additional genetic affinity to Southeast Asian indicine breeds. Our findings support the hypothesis of aurochs introgression into African taurine and generate a novel hypothesis that the origin of indicine ancestry in Africa might be different indicine populations than the ones found in North India today.

Global genetic diversity, introgression, and evolutionary adaptation of indicine cattle revealed by whole genome sequencing

Indicine cattle, also referred to as zebu (Bos taurus indicus), play a central role in pastoral communities across a wide range of agro-ecosystems, from extremely hot semiarid regions to hot humid tropical regions. However, their adaptive genetic changes following their dispersal into East Asia from the Indian subcontinent have remained poorly documented. Here, we characterize their global genetic diversity using high-quality whole-genome sequencing data from 354 indicine cattle of 57 breeds/populations, including major indicine phylogeographic groups worldwide. We reveal their probable migration into East Asia was along a coastal route rather than inland routes and we detected introgression from other bovine species. Genomic regions carrying morphology-, immune-, and heat-tolerance-related genes underwent divergent selection according to Asian agro-ecologies. We identify distinct sets of loci that contain promising candidate variants for adaptation to hot semi-arid and hot humid tropical ecosystems. Our results indicate that the rapid and successful adaptation of East Asian indicine cattle to hot humid environments was promoted by localized introgression from banteng and/or gaur. Our findings provide insights into the history and environmental adaptation of indicine cattle.

Genome-Wide Single-Nucleotide Polymorphism-Based Genomic Diversity and Runs of Homozygosity for Selection Signatures in Equine Breeds

The horse, one of the most domesticated animals, has been used for several purposes, like transportation, hunting, in sport, or for agriculture-related works. Kathiawari, Marwari, Manipuri, Zanskari, Bhutia, Spiti, and Thoroughbred are the main breeds of horses, particularly due to their agroclimatic adaptation and role in any kind of strong physical activity, and these characteristics are majorly governed by genetic factors. The genetic diversity and phylogenetic relationship of these Indian equine breeds using microsatellite markers have been reported, but further studies exploring the SNP diversity and runs of homozygosity revealing the selection signature of breeds are still warranted. In our study, the identification of genes that play a vital role in muscle development is performed through SNP detection via the whole-genome sequencing approach. A total of 96 samples, categorized under seven breeds, and 620,721 SNPs were considered to ascertain the ROH patterns amongst all the seven breeds. Over 5444 ROH islands were mined, and the maximum number of ROHs was found to be present in Zanskari, while Thoroughbred was confined to the lowest number of ROHs. Gene enrichment of these ROH islands produced 6757 functional genes, with AGPAT1, CLEC4, and CFAP20 as important gene families. However, QTL annotation revealed that the maximum QTLs were associated with Wither's height trait ontology that falls under the growth trait in all seven breeds. An Equine SNP marker database (EqSNPDb) was developed to catalogue ROHs for all these equine breeds for the flexible and easy chromosome-wise retrieval of ROH along with the genotype details of all the SNPs. Such a study can reveal breed divergence in different climatic and ecological conditions.

Local ancestry and selection in admixed Sanjiang cattle

The majority of native cattle are taurine × indicine cattle of diverse phenotypes in the central region of China. Sanjiang cattle, a typical breed in the central region, play a central role in human livelihood and have good adaptability, including resistance to dampness, heat, roughage, and disease, and are thus regarded as an important genetic resource. However, the genetic history of the successful breed remains unknown. Here, we sequenced 10 Sanjiang cattle genomes and compared them to the 70 genomes of 5 representative populations worldwide. We characterized the genomic diversity and breed formation process of Sanjiang cattle and found that Sanjiang cattle have a mixed ancestry of indicine (55.6%) and taurine (33.2%) dating to approximately 30 generations ago, which has shaped the genome of Sanjiang cattle. Through ancestral fragment inference, selective sweep and transcriptomic analysis, we identified several genes linked to lipid metabolism, immune regulation, and stress reactions across the mosaic genome of Sanjiang cattle showing an excess of taurine or indicine ancestry. Taurine ancestry might contribute to meat quality, and indicine ancestry is more conducive to adaptation to hot climate conditions, making Sanjiang cattle a valuable genetic resource for the central region of China. Our results will help us understand the evolutionary history and ancestry components of Sanjiang cattle, which will provide a reference for resource conservation and selective breeding of Chinese native cattle.

Identification of candidate lethal haplotypes and genomic association with post-natal mortality and reproductive traits in Nellore cattle

The wide use of genomic information has enabled the identification of lethal recessive alleles that are the major genetic causes of reduced conception rates, longer calving intervals, or lower survival for live-born animals. This study was carried out to screen the Nellore cattle genome for lethal recessive haplotypes based on deviation from the expected population homozygosity, and to test SNP markers surrounding the lethal haplotypes region for association with heifer rebreeding (HR), post-natal mortality (PNM) and stayability (STAY). This approach requires genotypes only from apparently normal individuals and not from affected embryos. A total of 62,022 animals were genotyped and imputed to a high-density panel (777,962 SNP markers). Expected numbers of homozygous individuals were calculated, and the probabilities of observing 0 homozygotes was obtained. Deregressed genomic breeding values [(G)EBVs] were used in a GWAS to identify candidate genes and biological mechanisms affecting HR, STAY and PNM. In the functional analyses, genes within 100 kb down and upstream of each significant SNP marker, were researched. Thirty haplotypes had high expected frequency, while no homozygotes were observed. Most of the alleles present in these haplotypes had a negative mean effect for PNM, HR and STAY. The GWAS revealed significant SNP markers involved in different physiological mechanisms, leading to harmful effect on the three traits. The functional analysis revealed 26 genes enriched for 19 GO terms. Most of the GO terms found for biological processes, molecular functions and pathways were related to tissue development and the immune system. More phenotypes underlying these putative regions in this population could be the subject of future investigation. Tests to find putative lethal haplotype carriers could help breeders to eliminate them from the population or manage matings in order to avoid homozygous.

Global dispersal and adaptive evolution of domestic cattle: a genomic perspective

Domestic cattle have spread across the globe and inhabit variable and unpredictable environments. They have been exposed to a plethora of selective pressures and have adapted to a variety of local ecological and management conditions, including UV exposure, diseases, and stall-feeding systems. These selective pressures have resulted in unique and important phenotypic and genetic differences among modern cattle breeds/populations. Ongoing efforts to sequence the genomes of local and commercial cattle breeds/populations, along with the growing availability of ancient bovid DNA data, have significantly advanced our understanding of the genomic architecture, recent evolution of complex traits, common diseases, and local adaptation in cattle. Here, we review the origin and spread of domestic cattle and illustrate the environmental adaptations of local cattle breeds/populations.

Mitochondrial DNA diversity of D-loop region in three native Turkish cattle breeds

This study aimed to reveal the genetic variability of mitochondrial DNA (mtDNA) displacement-loop (D-loop) region in 62 animals belonging to three native Turkish cattle breeds, namely Anatolian Black (AB), East Anatolian Red (EAR) and Zavot (ZAV), and to conduct phylogenetic relationship analyses to obtain deeper information on their genetic origin and breeding history by comparison of 6 taurine and 11 indicine breeds, together with 66 polymorphic sites, a total of 31 haplotypes, of which 15, 10 and 6 were detected in AB, EAR and ZAV, respectively. Mean nucleotide and haplotype diversity were 0.01 and 0.891, respectively, whereas the genetic differentiation derived from Wright's F ST index was 0.174 across the breeds. A significant level of total variation (17.42 %) was observed among breeds in molecular variance analysis. Six main haplogroups (T, T1, T2, T3, Q and I2) were detected in Anatolian cattle populations, where T3 was the most frequent among breeds (43.55 %), whereas I2, an indicine specific haplogroup, was observed only in ZAV. At the breed level, phylogenetic analyses supported by 198 sequences of 17 cattle breeds and 3 outgroup species retrieved from the GenBank clustered native Turkish cattle breeds with the taurine group rather than the indicine one, as expected. However, indicine admixture at low frequency (8.89 %) was detected in the ZAV breed for the first time due to more likely gene flow from indicine cattle breeds raised in neighbour countries, particularly Iran. This finding should be further investigated in all native Turkish and indicine cattle breeds from nearby countries to clarify gene flow and indicine admixture in Anatolian cattle.

Analysis of runs of homozygosity of cattle living in different climate zones

Aim of this study was to analyze the distribution and characteristics of runs of homozygosity in Bos taurus taurus and Bos taurus indicus breeds, as well as their crosses, farmed all around the world. With this aim in view, we used single-nucleotide polymorphisms (SNP) genotypes for 3,263 cattle belonging to 204 different breeds. After quality control, 23,311 SNPs were retained for the analysis. Animals were divided into seven different groups: 1) continental taurus, 2) temperate taurus, 3) temperate indicus, 4) temperate composite, 5) tropical taurus, 6) tropical indicus, and 7) tropical composite. The climatic zones were created according to the latitude of the breeds' country of origin: i) continental, latitude ≥ 45°; ii) temperate, 45°< Latitude >23.26°; iii) tropics, latitude ≤ 23.26°. Runs of homozygosity were computed as 15 SNPs spanning in at least 2 Mb; number of ROH per animal (nROH), average ROH length (meanMb), and ROH-based inbreeding coefficients (FROH) were also computed. Temperate indicus showed the largest nROH, whereas Temperate taurus the lowest value. Moreover, the largest meanMb was observed for Temperate taurus, whereas the lowest value for Tropics indicus. Temperate indicus breeds showed the largest FROH values. Genes mapped in the identified ROH were reported to be associated with the environmental adaptation, disease resistance, coat color determinism, and production traits. Results of the present study confirmed that runs of homozygosity could be used to identify genomic signatures due to both artificial and natural selection.

Assessing the Role of Ancestral Fragments and Selection Signatures by Whole-Genome Scanning in Dehong Humped Cattle at the China-Myanmar Border

Dehong humped cattle are precious livestock resources of Yunnan Province, China; they have typical zebu traits. Here, we investigated their genetic characteristics using whole-genome resequencing data of Dehong humped animals (n = 18). When comparing our data with the publicly-available data, we found that Dehong humped cattle have high nucleotide diversity. Based on clustering models in a population structure analysis, Dehong humped cattle had a mutual genome ancestor with Chinese and Indian indicine cattle. While using the RFMix method, it is speculated that the body sizes of Dehong humped cattle were influenced by the Chinese indicine segments and that the immune systems of Dehong humped cattle were affected by additional ancestral segments (Indian indicine). Furthermore, we explored the position selection regions harboring genes in the Dehong humped cattle, which were related to heat tolerance (FILIP1L, ABHD6) and immune responses (GZMM, PRKCZ, STOML2, LRBA, PIK3CD). Notably, missense mutations were detected in the candidate gene ABHD6 (c.870C>A p.Asp290Glu; c.987C>A p.Ser329Arg). The missense mutations may have implications for Dehong humped cattle adaptation to hot environments. This study provides valuable genomic resource data at the genome-wide level and paves the way for future genetic breeding work in the Dehong humped cattle.

Whole-Genome Sequencing of Endangered Dengchuan Cattle Reveals Its Genomic Diversity and Selection Signatures

Dengchuan cattle are the only dairy yellow cattle and endangered cattle among Yunnan native cattle breeds. However, its genetic background remains unclear. Here, we performed whole-genome sequencing of ten Dengchuan cattle. Integrating our data with the publicly available data, Dengchuan cattle were observed to be highly interbred than other cattle in the dataset. Furthermore, the positive selective signals were mainly manifested in candidate genes and pathways related to milk production, disease resistance, growth and development, and heat tolerance. Notably, five genes (KRT39, PGR, KRT40, ESR2, and PRKACB) were significantly enriched in the estrogen signaling pathway. Moreover, the missense mutation in the PGR gene (c.190T > C, p.Ser64Pro) showed a homozygous mutation pattern with higher frequency (83.3%) in Dengchuan cattle. In addition, a large number of strong candidate regions matched genes and QTLs related to milk yield and composition. Our research provides a theoretical basis for analyzing the genetic mechanism underlying Dengchuan cattle with excellent lactation and adaptability, crude feed tolerance, good immune performance, and small body size and also laid a foundation for genetic breeding research of Dengchuan cattle in the future.

Whole-Genome Analyses Reveal Genomic Characteristics and Selection Signatures of Lincang Humped Cattle at the China-Myanmar Border

The location on the Yunnan border with Myanmar and its unique cultural landscape has shaped Lincang humped cattle over time. In the current study, we investigated the genetic characteristics of 22 Lincang humped cattle using whole-genome resequencing data. We found that Lincang humped cattle derived from both Indian indicine and Chinese indicine cattle depicted higher levels of genomic diversity. Based on genome-wide scans, candidate genomic regions were identified that were potentially involved in local thermal and humid environmental adaptions, including genes associated with the body size (TCF12, SENP2, KIF1C, and PFN1), immunity (LIPH, IRAK3, GZMM, and ELANE), and heat tolerance (MED16, DNAJC8, HSPA4, FILIP1L, HELB, BCL2L1, and TPX2). Missense mutations were detected in candidate genes IRAK3, HSPA4, and HELB. Interestingly, eight missense mutations observed in the HELB gene were specific to the indicine cattle pedigree. These mutations may reveal differences between indicine and taurine cattle adapted to variable climatic conditions. Our research provides new insights into the genetic characteristics of Lincang humped cattle representing Lincang and Pu'er areas as an important channel for the migration of Indian indicine from domestication centers toward southwestern China.

Zeboid cow milk: physicochemical quality indicator

Introduction. A herd of zeboid cattle was created by the Snegiri Scientific and Experimental Farm (Moscow region, Russia) as a result of long-term selection and crossbreeding zebu (Bos indicus L.) with cattle (Bos taurus L.). These hybrid cows have good physiological parameters, high resistance to diseases, and a significant adaptive potential. The quality of milk produced by zebu cows at different lactation and milking times has not been studied as well as their milking capacity. Therefore, we aimed to assess the variability of specific physicochemical indicators of milk produced by Snegiri’s zeboid dairy herd. Study objects and methods. The milk of 193 zeboid cows (6–12% of zebu blood) from the Snegiri Farm was analyzed by standard methods for quality indicators such as fat, nonfat milk solids, density, bound water, freezing point, protein, and lactose. Then, we determined how these indicators changed depending on the lactation number and the time of milking (morning/evening). Statistical analysis was applied to process the data. Results and discussion. Such indicators as nonfat milk solids, density, bound water, freezing point, protein, and lactose of zeboid cow milk were consistent with the normal indicators for raw cow’s milk. Only its fat content (4.39%) exceeded the norm. We found no correlation between the quality of milk and the number of lactations. However, the evening milk was more concentrated, with a significant increase in nonfat milk solids and density, as well as with a lower freezing point. Conclusion. Zeboid cows, which can be bred in suboptimal conditions, produce milk suitable for dairy products since it has a high fat content regardless of lactation and milking time.

TAS2R16 introgression from banteng into indigenous Chinese cattle

Historical hybridization between southern indigenous Chinese cattle and banteng has been well-documented and has resulted in gene introgression. Bitter taste receptors were reported in indigenous cattle as a result of introgression from banteng. To determine the level of introgression of the taste 2 receptor member 16 (TAS2R16) gene from banteng into Chinese cattle, two missense mutations in the bovine TAS2R16 gene were examined. Here, we explored the prevalence of the two variants in 28 indigenous Chinese cattle and banteng breeds (comprising 750 individuals) to determine the influence of banteng introgressions on Chinese cattle based on PCR and DNA sequencing. In our study, the two mutant alleles had a higher frequency distribution in southern China with strong geographic distribution, especially in the south-central and southeast areas. In conclusion, this study examines the impact of introgression on the frequency distributions of mutations in variable regions and the subsequent adaptation of Chinese indigenous cattle to different environmental conditions.

Bos taurus haplotypes segregating in Nellore (Bos indicus) cattle

Brazil is the largest exporter of beef in the world, and most of that beef derives from Nellore cattle. Although considered a zebu breed (Bos indicus), the history of Nellore cattle in Brazil is marked by the importation of bulls from India, the use of a Creole taurine (Bos taurus) maternal lineage to quickly expand the herds and backcrossing to Nellore bulls to recover zebu ancestry. As a consequence, the current Brazilian Nellore population carries an average taurine ancestry of approximately 1%. Although that percentage seems small, some taurine variants deviate substantially from that average, with the better-known cases being the PLAG1-Q haplotype involved with body size variation and the Guarani (P_G ) polled variant producing hornless animals. Here, we report taurine haplotypes in 9074 Nellore animals genotyped for 539 657 imputed SNP markers. Apart from PLAG1-Q and P_G , our analysis further revealed common taurine haplotypes (>3%) spanning genes related to immunity, growth, reproduction and hair and skin phenotypes. Using data from 22 economically important traits, we showed that many of the major QTL previously reported in the breed are at least partially driven by taurine haplotypes. As B. taurus and B. indicus haplotypes are highly divergent, presenting widely different sets of functional variants, our results provide promising targets for future scrutiny in Nellore cattle.

Mutant alleles differentially shape fitness and other complex traits in cattle

Mutant alleles (MAs) that have been classically recognised have large effects on phenotype and tend to be deleterious to traits and fitness. Is this the case for mutations with small effects? We infer MAs for 8 million sequence variants in 113k cattle and quantify the effects of MA on 37 complex traits. Heterozygosity for variants at genomic sites conserved across 100 vertebrate species increase fertility, stature, and milk production, positively associating these traits with fitness. MAs decrease stature and fat and protein concentration in milk, but increase gestation length and somatic cell count in milk (the latter indicative of mastitis). However, the frequency of MAs decreasing stature and fat and protein concentration, increasing gestation length and somatic cell count were lower than the frequency of MAs with the opposite effect. These results suggest bias in the mutations direction of effect (e.g. towards reduced protein in milk), but selection operating to reduce the frequency of these MAs. Taken together, our results imply two classes of genomic sites subject to long-term selection: sites conserved across vertebrates show hybrid vigour while sites subject to less long-term selection show a bias in mutation towards undesirable alleles.

Genome analyses revealed genetic admixture and selection signatures in Bos indicus

The genomic diversity and relationship among seven diverse cattle breeds viz. Sahiwal, Tharparkar, Gir, Vechur, Ongole, Kangayam and Hariana were investigated in 132 random samples based on high density SNP array comprising > 777 K SNPs. A total of 1993 SNPs (0.25% of the total) having greater power (F_ST ≥ 0.20) to differentiate these cattle populations were identified, and utilized to partition genome of each animal into a predefined number of clusters. The structure of these cattle indicated shared ancestry of dairy breeds viz. Gir, Tharparkar and Sahiwal. Most of the animals (> 76%) of different populations under study except Vechur clustered into their own group of animals called breed. Vechur population retained highest rate of admixture, consistent with its crossing with other breeds. Ongole, Kangayam and Hariana shared comparatively less of their genome (≤ 15%) with other breeds. The study indicated that all seven breeds evolved from their independent ancestry but there was intermixing of these breeds in the recent past. The selection signatures identified between draft (Kangayam) and dairy breeds included several genes like FAM19A2, RAB31P, BEST3, DGKA, AHCY, PIGU and PFKP which are involved in immune response, metabolic pathway, transportation of glucose and sugars, signaling pathways, cellular processes, cell division and glycolysis regulation, respectively. Moreover, these genomic regions also harbour QTLs affecting milk performance traits. The signatures were also identified even between the dairy breeds. In comparison to large-sized cattle, there were significant differences in the number of QTLs affecting production (body weight, growth rate etc.) and morphological traits (height) in short-statured Vechur breed. The presence of HMGA2 gene in the selection signature on chromosome 5 may explain the variations in stature between these cattle.

Assessing Genomic Diversity and Productivity Signatures in Dianzhong Cattle by Whole-Genome Scanning

Dianzhong cattle is a classic Chinese indigenous cattle breed with historical records dating back to 200 BC. But with its genomic differences having not been clearly elucidated, the quest for genomic characterization will be an essential step towards understanding the genomic basis of productivity and adaptation to survival under Chinese farming systems. Here we compared 10 Dianzhong cattle (four newly sequenced and six downloaded) with 29 published genomes of three underlying ancestral populations (Chinese zebu, Indian zebu, and Yanbian cattle) to characterize the genomic variations of Dianzhong cattle. Dianzhong cattle has a high nucleotide diversity (0.0034), second only to Chinese zebu. Together with analyses of linkage disequilibrium decay and runs of homozygosity, Dianzhong cattle displayed higher genomic diversity and weaker artificial selection compared with Yanbian cattle. From a selective sweep analysis by four methods (Fst, π-ratio, XP-CLR, and XP-EHH), the positive selective signals were mainly manifested in candidate genes and pathways related to heat resistance, growth and development, fat deposition, and male reproduction. Missense mutations were detected in candidate genes, SDS (c.944C > A and p.Ala315Glu), PDGFD (c.473A > G and p.Lys158Arg), and DDX4 (rs460251486, rs722912933, and rs517668236), which related to heat resistance, fat deposition, and spermatogenesis, respectively. Our findings unravel, at the genome-wide level, the unique diversity of Dianzhong cattle while emphasizing the opportunities for improvement of livestock productivity in further breeding programs.

The Quest for Genes Involved in Adaptation to Climate Change in Ruminant Livestock

Livestock radiated out from domestication centres to most regions of the world, gradually adapting to diverse environments, from very hot to sub-zero temperatures and from wet and humid conditions to deserts. The climate is changing; generally global temperature is increasing, although there are also more extreme cold periods, storms, and higher solar radiation. These changes impact livestock welfare and productivity. This review describes advances in the methodology for studying livestock genomes and the impact of the environment on animal production, giving examples of discoveries made. Sequencing livestock genomes has facilitated genome-wide association studies to localize genes controlling many traits, and population genetics has identified genomic regions under selection or introgressed from one breed into another to improve production or facilitate adaptation. Landscape genomics, which combines global positioning and genomics, has identified genomic features that enable animals to adapt to local environments. Combining the advances in genomics and methods for predicting changes in climate is generating an explosion of data which calls for innovations in the way big data sets are treated. Artificial intelligence and machine learning are now being used to study the interactions between the genome and the environment to identify historic effects on the genome and to model future scenarios.

Whole-genome sequencing of endangered Zhoushan cattle suggests its origin and the association of MC1R with black coat colour

Zhoushan cattle are an endangered cattle breed in the Zhoushan islands in China. Since Zhoushan cattle have been bred in isolation, they show unique characteristics, such as dark black coat colour. However, no studies have been conducted on the genome of Zhoushan cattle. Here, we performed whole-genome sequencing of seven individuals of Zhoushan cattle and nine cattle in Wenling, geographically close to the Zhoushan islands. By integrating our data and publicly-available data, we found that Zhoushan cattle are genetically highly similar to Bos indicus cattle in south-eastern China. Furthermore, by identifying the genomic regions shared between Zhoushan cattle and Angus cattle, a Bos taurus breed, we found that the p.F195L mutation in melanocyte-stimulating hormone receptor (MC1R) could be associated with their dark black coat colour. Taken together, our results provide a valuable resource for characterising the uniqueness of Zhoushan cattle.

Suggested Absence of Horizontal Transfer of Retrotransposons between Humans and Domestic Mammal Species

Transposable element sequences are usually vertically inherited but have also spread across taxa via horizontal transfer. Previous investigations of ancient horizontal transfer of transposons have compared consensus sequences, but this method resists detection of recent single or low copy number transfer events. The relationship between humans and domesticated animals represents an opportunity for potential horizontal transfer due to the consistent shared proximity and exposure to parasitic insects, which have been identified as plausible transfer vectors. The relatively short period of extended human-animal contact (tens of thousands of years or less) makes horizontal transfer of transposons between them unlikely. However, the availability of high-quality reference genomes allows individual element comparisons to detect low copy number events. Using pairwise all-versus-all megablast searches of the complete suite of retrotransposons of thirteen domestic animals against human, we searched a total of 27,949,823 individual TEs. Based on manual comparisons of stringently filtered BLAST search results for evidence of vertical inheritance, no plausible instances of HTT were identified. These results indicate that significant recent HTT between humans and domesticated animals has not occurred despite the close proximity, either due to the short timescale, inhospitable recipient genomes, a failure of vector activity, or other factors.

Assessing the accuracy of imputation in the Gyr breed using different SNP panels

The aim of this study was to evaluate the accuracy of imputation in a Gyr population using two medium-density panels (Bos taurus - Bos indicus) and to test whether the inclusion of the Nellore breed increases the imputation accuracy in the Gyr population. The database consisted of 289 Gyr females from Brazil genotyped with the GGP Bovine LDv4 chip containing 30 000 SNPs and 158 Gyr females from Colombia genotyped with the GGP indicus chip containing 35 000 SNPs. A customized chip was created that contained the information of 9109 SNPs (9K) to test the imputation accuracy in Gyr populations; 604 Nellore animals with information of LD SNPs tested in the scenarios were included in the reference population. Four scenarios were tested: LD9K_30KGIR, LD9K_35INDGIR, LD9K_30KGIR_NEL, and LD9K_35INDGIR_NEL. Principal component analysis (PCA) was computed for the genomic matrix and sample-specific imputation accuracies were calculated using Pearson's correlation (CS) and the concordance rate (CR) for imputed genotypes. The results of PCA of the Colombian and Brazilian Gyr populations demonstrated the genomic relationship between the two populations. The CS and CR ranged from 0.88 to 0.94 and from 0.93 to 0.96, respectively. Among the scenarios tested, the highest CS (0.94) was observed for the LD9K_30KGIR scenario. The present results highlight the importance of the choice of chip for imputation in the Gyr breed. However, the variation in SNPs may reduce the imputation accuracy even when the chip of the Bos indicus subspecies is used.

Human adaptation, demography and cattle domestication: an overview of the complexity of lactase persistence in Africa

Lactase persistence (LP) is a genetically-determined trait that is prevalent in African, European and Arab populations with a tradition of animal herding and milk consumption. To date, genetic analyses have identified several common variants that are associated with LP. Furthermore, data have indicated that these functional alleles likely have been maintained in pastoralist populations due to the action of recent selection, exemplifying the ongoing evolution of anatomically modern humans. Additionally, demographic history has also played a role in the geographic distribution of LP and associated alleles in Africa. In particular, the migration of ancestral herders and their subsequent admixture with local populations were integral to the spread of LP alleles and the culture of pastoralism across the continent. The timing of these demographic events was often correlated with known major environmental changes and/or the ability of domesticated cattle to resist/avoid infectious diseases. This review summarizes recent advances in our understanding of the genetic basis and evolutionary history of LP, as well as the factors that influenced the origin and spread of pastoralism in Africa.

Inference of Ancestries and Heterozygosity Proportion and Genotype Imputation in West African Cattle Populations

Several studies have evaluated computational methods that infer the haplotypes from population genotype data in European cattle populations. However, little is known about how well they perform in African indigenous and crossbred populations. This study investigates: (1) global and local ancestry inference; (2) heterozygosity proportion estimation; and (3) genotype imputation in West African indigenous and crossbred cattle populations. Principal component analysis (PCA), ADMIXTURE, and LAMP-LD were used to analyse a medium-density single nucleotide polymorphism (SNP) dataset from Senegalese crossbred cattle. Reference SNP data of East and West African indigenous and crossbred cattle populations were used to investigate the accuracy of imputation from low to medium-density and from medium to high-density SNP datasets using Minimac v3. The first two principal components differentiated Bos indicus from European Bos taurus and African Bos taurus from other breeds. Irrespective of assuming two or three ancestral breeds for the Senegalese crossbreds, breed proportion estimates from ADMIXTURE and LAMP-LD showed a high correlation (r ≥ 0.981). The observed ancestral origin heterozygosity proportion in putative F1 crosses was close to the expected value of 1.0, and clearly differentiated F1 from all other crosses. The imputation accuracies (estimated as correlation) between imputed and the real data in crossbred animals ranged from 0.142 to 0.717 when imputing from low to medium-density, and from 0.478 to 0.899 for imputation from medium to high-density. The imputation accuracy was generally higher when the reference data came from the same geographical region as the target population, and when crossbred reference data was used to impute crossbred genotypes. The lowest imputation accuracies were observed for indigenous breed genotypes. This study shows that ancestral origin heterozygosity can be estimated with high accuracy and will be far superior to the use of observed individual heterozygosity for estimating heterosis in African crossbred populations. It was not possible to achieve high imputation accuracy in West African crossbred or indigenous populations based on reference data sets from East Africa, and population-specific genotyping with high-density SNP assays is required to improve imputation.

A novel missense mutation within KRT75 gene strongly affects heat stress in Chinese cattle

The KRT75 gene (Keratin 75) is a member of the type II epithelial α-keratin gene family which plays a key role in hair and nail formation. And the coat conformation affects heat tolarence in mammals. Therefore, the aim of this study was to identify novel single nucleotide polymorphisms (SNPs) of the KRT75 gene and further evaluate its relation to heat stress in Chinese cattle. A missense mutation (NC_037332.1: g.1052 T > C) of the bovine KRT75 was identified using the Bovine Genome Variation Database (BGVD). The g.1052 T > C variant was then genotyped in 519 individuals of 22 cattle breeds. Further analyses showed that the frequency of T allele in Chinese indigenous cattle breeds gradually diminished from northern groups to southern groups, whereas the frequency of C allele displayed a contrary patternl. Simultaneously, the frequency of the CC and CT genotype for southern groups was much greater than that of the TT genotype. Additionally, association analysis showed the genotypes were remarkably associated with mean annual temperature (T), relative humidity (RH) and temperature humidity index (THI) (P < 0.01). Our results demonstrated that the KRT75 gene might be a candidate gene associated with the heat stress in Chinese cattle.

Demographic history and admixture dynamics in African Sahelian populations

The Sahel/Savannah belt of Africa is a contact zone between two subsistence systems (nomadic pastoralism and sedentary farming) and of two groups of populations, namely Eurasians penetrating from northern Africa southwards and sub-Saharan Africans migrating northwards. Because pastoralism is characterized by a high degree of mobility, it leaves few significant archaeological traces. Demographic history seen through the lens of population genetic studies complements our historical and archaeological knowledge in this African region. In this review, we highlight recent advances in our understanding of demographic history in the Sahel/Savannah belt as revealed by genetic studies. We show the impact of food-producing subsistence strategies on population structure and the somewhat different migration patterns in the western and eastern part of the region. Genomic studies show that the gene pool of various groups of Sahelians consists in a complex mosaic of several ancestries. We also touch upon various signals of genetic adaptations such as lactase persistence, taste sensitivity and malaria resistance, all of which have different distribution patterns among Sahelian populations. Overall, genetic studies contribute to gain a deeper understanding about the demographic and adaptive history of human populations in this specific African region and beyond.

Evolution and domestication of the Bovini species

Domestication of the Bovini species (taurine cattle, zebu, yak, river buffalo and swamp buffalo) since the early Holocene (ca. 10 000 BCE) has contributed significantly to the development of human civilization. In this study, we review recent literature on the origin and phylogeny, domestication and dispersal of the three major Bos species - taurine cattle, zebu and yak - and their genetic interactions. The global dispersion of taurine and zebu cattle was accompanied by population bottlenecks, which resulted in a marked phylogeographic differentiation of the mitochondrial and Y-chromosomal DNA. The high diversity of European breeds has been shaped through isolation-by-distance, different production objectives, breed formation and the expansion of popular breeds. The overlapping and broad ranges of taurine and zebu cattle led to hybridization with each other and with other bovine species. For instance, Chinese gayal carries zebu mitochondrial DNA; several Indonesian zebu descend from zebu bull × banteng cow crossings; Tibetan cattle and yak have exchanged gene variants; and about 5% of the American bison contain taurine mtDNA. Analysis at the genomic level indicates that introgression may have played a role in environmental adaptation.