Whole-genome resequencing reveals genetic diversity and selection characteristics of dairy goat

Genomic Dissection of Chinese Yangtze River Delta White Goat Based on Whole Genome Sequencing

The conservation and utilization of livestock genetic resources is essential for the maintenance of biodiversity and breed innovation. Whole genome sequencing (WGS) was performed on 90 samples from Chinese Yangtze River Delta White goats (YRD), sourced from two populations of Chongming island white goats and Haimen white goats, aiming to dissect their genomic characteristics. In addition, 262 WGS data from nine other breeds of goats were downloaded from the NCBI database. These WGS data obtained were used to identify and analyze genetic variation with the goat reference genome, and the genetic structure of goat populations was analyzed. Through selective sweep analysis, the selection-signature genes and their polymorphic features were identified. It was found that the most significant genomic selection region in YRD goats was in the region of 62.9-64.6 Mb on chromosome 13, which contained genes related to the coat color and muscle growth of the goats. Nucleotide diversity of MYH7B, a gene related to the development of the goat's skeletal muscle, within the Yangtze River Delta white goat population was significantly lower than in other domestic and foreign goat breeds, suggesting that the gene was subject to selection. In addition, the IGF2BP2 gene, reported to be associated with litter size in goats, showed clear selection-signature characteristics in the Boer goats compared to the YRD goats.

Leveraging Whole-Genome Resequencing to Uncover Genetic Diversity and Promote Conservation Strategies for Ruminants in Asia

Whole-genome resequencing (WGRS) is a critical branch of whole-genome sequencing (WGS), primarily targeting species with existing reference genomes. By aligning sequencing data to the reference genome, WGRS enables precise detection of genetic variations in individuals or populations. As a core technology in genomic research, WGS holds profound significance in ruminant studies. It not only reveals the intricate structure of ruminant genomes but also provides essential data for deciphering gene function, variation patterns, and evolutionary processes, thereby advancing the exploration of ruminant genetic mechanisms. However, WGS still faces several challenges, such as incomplete and inaccurate genome assembly, as well as the incomplete annotation of numerous unknown genes or gene functions. Although WGS can identify a vast number of genomic variations, the specific relationships between these variations and phenotypes often remain unclear, which limits its potential in functional studies and breeding applications. By performing WGRS on multiple samples, these assembly challenges can be effectively addressed, particularly in regions with high repeat content or complex structural variations. WGRS can accurately identify subtle variations among different individuals or populations and further elucidate their associations with specific traits, thereby overcoming the limitations of WGS and providing more precise genetic information for functional research and breeding applications. This review systematically summarizes the latest applications of WGRS in the analysis of ruminant genetic structures, genetic diversity, economic traits, and adaptive traits, while also discussing the challenges faced by this technology. It aims to provide a scientific foundation for the improvement and conservation of ruminant genetic resources.

Investigation of selection signatures of dairy goats using whole-genome sequencing data

Dairy goats, a livestock species with a long history of milk production, are essential for the economic advancement of nations, particularly in regions experiencing growth. In this study, we gathered whole-genome resequencing data of 58 goats, including 34 dairy goats and 24 wild goats (Bezoar), to explore the selection signatures linked to milk production traits using ROH (Runs of homozygosity), CLR (composite likelihood ratio), Fst (Fixation index), XP-EHH (Ex-tended haplotype homozygosity across populations) and XP-CLR(Cross-population composite likelihood ratio test) methods. Analysis of five tests of selection signatures for dairy goats revealed a total of 210 genes, with 24 genes consistently identified in at least two approaches. These genes are associated with milk fat, milk protein, and fat yield. Gene enrichment analysis highlighted important GO and KEGG pathways related to milk production, such as the "acyl-CoA metabolic process", "glycerolipid biosynthetic process", "cellular response to fatty ac-id", "hormone metabolic process", "Galactose metabolism". Additionally, genes linked to repro-duction, immune response, and environmental adaptation were identified in dairy goats. The findings from our study offer profound understanding into the critical economic features of dairy goats and offer practical guidance for the improvement and development of crossbreeding initiatives across different dairy goat breeds.

Genome-Wide Runs of Homozygosity Reveal Inbreeding Levels and Trait-Associated Candidate Genes in Diverse Sheep Breeds

BACKGROUND

Quantifying and controlling the inbreeding level in livestock populations is crucial for the long-term sustainability of animal husbandry. However, the extent of inbreeding has not been fully understood in sheep populations on a global scale.

METHODS

Here, we analyzed high-depth genomes of 210 sheep from 20 worldwide breeds to identify the pattern and distribution of genome-wide runs of homozygosity (ROH) and detect candidate selected genes in ROH islands for agronomic and phenotypic traits.

RESULTS

Leveraging whole-genome sequencing data, we found a large number of short ROH (e.g., <1.0 Mb) in all breeds and observed the overall higher values of ROH statistics and inbreeding coefficient in European breeds than in Asian breeds and Dorper sheep. We identified some well-known candidate genes (e.g., CAMK4, HOXA gene family, ALOX12, FGF11, and MTOR) and 40 novel genes (e.g., KLHL1, FGFRL1, WDR62, GDF6, KHDRBS2, and PAX1) that are functionally associated with fecundity, body size, and wool-related traits in sheep. Based on the candidate genes, we revealed different genetic bases for the fecundity traits of European and Asian sheep.

CONCLUSIONS

This study improves the resolution of ROH detection and provides new insights into genomic inbreeding and trait architecture in sheep as well as useful markers for future breeding practice.

Whole genome and transcriptome analyses in dairy goats identify genetic markers associated with high milk yield

Milk production is the most important economic trait of dairy goats and a key indicator for genetic improvement and breeding. However, milk yield is a complex phenotypic trait, and its genetic mechanisms are still not fully understood. This study focuses on dairy goats and non-dairy goats. By analyzing the population structure of these two groups, we found that there is a significant genetic distance between the populations of dairy goats and non-dairy goats. Using SNP and Indel analyses to identify selection signals, we identified several genes associated with milk production traits, including MPP7, PRPF6, DNAJC5, TPD52L2, HNF4G, LAMA3, FAM13A, and EPHA5. Through longitudinal GWAS of the milk production traits of 298 dairy goats, we discovered additional genes such as TRNAS-GGA-102, TTC39C, LAMA3, ANKRD29, NPC1, C24H18orf8, LOC108633789, RIOK3, TMEM241, CABLES1, LOC108633781, and RBBP8. Transcriptome sequencing of breast tissues at different lactation stages reveals dynamic LAMA3 expression changes. Three non-synonymous mutations in LAMA3 are identified, with the TT genotype at one site correlating significantly with average milk production in dairy goats. Our study discovered new genetic markers for improving dairy goat genetics and provided valuable insights into the genetic mechanisms underlying complex traits.

Effect of Dietary Addition of Lentinus edodes on Rumen Flora, Lactation, and Health of Dairy Goats

Lentinus edodes (LE) is a nutrient-rich medicinal fungus with potential applications in animal nutrition; however, its effects on dairy goats remain underexplored. This study investigated the impact of dietary LE addition on rumen microbiota, metabolic profiles, serum immunity, and milk quality in lactating dairy goats. Twenty Saanen goats were randomly assigned to a control group (CON, basal diet) or an LE group (basal diet + 25 g Lentinus edodes) for 56 days. Rumen fluid, serum, and milk samples were analyzed using 16S rDNA sequencing, metabolomics, and biochemical assays. The results showed that the addition of LE altered the microbial composition, decreasing the abundance of fibrobacterial flora and Treponema (p < 0.05) while increasing VadinHA49. Metabolomic analysis revealed elevated fumaric acid, lysophospholipids (LysoPE, LysoPG), and D-quinic acid in the rumen (p < 0.05). Serum immunoglobulin A (IgA), immunoglobulin G (IgG), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and tumor necrosis factor-α (TNF-α) levels were significantly enhanced (p < 0.05). The milk somatic cell count (SCC) was reduced by 52.8% (p = 0.005) at day 56, and protein, fat, and total solids increased significantly (p < 0.05). Enrichment of functional metabolites such as D-arabitol and D-tryptophan in milk further highlighted LE's role in improving product value. These findings demonstrate that LE optimizes rumen flora, enhances antioxidant and immune functions, and improves milk quality, supporting its use as a functional feed additive for dairy goats.

Examination of homozygosity runs and selection signatures in native goat breeds of Henan, China

Understanding the genomic characteristics of livestock is crucial for improving breeding efficiency and conservation efforts. However, there is a relative lack of information on the genetic makeup of local goat breeds in Henan, China. In this study, we identified runs of homozygosity (ROH), genomic inbreeding coefficients (FROH), and selection signatures in four breeds including Funiu White (FNW), Huai (HG), Lushan Bullleg (LS), and Taihang black (THB). The genomic analysis utilized a dataset of 46,278 SNP markers and 102 animals. A total of 342, 567, 1285, and 180 ROH segments were detected in FNW, HG, LS, and THB, respectively, with an average of 15.55, 29.84, 32.95, and 8.18 segments per individual. The lengths of ROH segments varied from 69.36 Mb in THB to 417.06 Mb in LS, with the most common lengths being 2-4 Mb and 4-8 Mb. The highest number of longest ROH segments (> 16 Mb) were found in LS (328) and the highest average FROH value was observed in LS (0.173), followed by HG (0.128), while the lowest FROH values were in THB (0.029) and FNW (0.070). Furthermore, the analysis of ROH islands and Composite Likelihood Ratio (CLR) identified a total of 175 significant genes. Among these, 25 genes were found to overlap, detected by both methods. These genes were associated with a diverse range of traits including reproductive ability (GPRIN3), weight (CCSER1), immune response (HERC5 and TIGD2), embryo development (NAP1L5), environmental adaptation (KLHL3, TRHDE, and IFNGR1), and milk characteristics (FAM13A). Significant Gene Ontology (GO) terms related to embryo skeletal system morphogenesis, brain ventricle development, and growth were also identified. This study helps reveal the genetic architecture of Henan goat breeds and provides valuable insights for the effective conservation and breeding programs of local goat breeds in Henan.

Screening of SNP Loci Related to Leg Length Trait in Leizhou Goats Based on Whole-Genome Resequencing

Leizhou goats can be classified into tall and short types based on their size and habits. The tall Leizhou goats are well-suited for grazing management due to their robust physique, while the dwarf types are smaller, grow rapidly, and are more appropriate for feeding management systems. In this study, whole-genome resequencing was conducted to identify genomic variants in 15 Tall-legged (TL) and 15 Short-legged (SL) Leizhou goats, yielding 8,641,229 high-quality SNPs in the Leizhou goat genome. Phylogenetic tree and principal component analyses revealed obvious genetic differentiation between the two groups. Fst and θπ analyses identified 420 genes in the TL group and 804 genes in the SL group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that the phosphatidylinositol signaling system is associated with growth and development. Additionally, Genome-Wide Association Study (GWAS) analysis identified eight genes linked to leg length, including B4GALT7 and NR1D1. Notably, the NC_030818.1 (g.53666634T > C) variant was significantly associated with leg length traits, where the CC genotype was linked to shorter legs and the TT genotype to longer legs. This study identifies candidate genes and molecular markers, serving as a reference point for breeding and genetic improvement efforts in Leizhou goats and other goat breeds.

Analysis of genetic evolutionary differences among four Tibetan pig populations in China

Tibetan pigs are a locally bred domestic pig breed originating from the Tibetan Plateau in China. They can be categorized into four distinct groups based on their geographical locations: Sichuan Tibetan pigs, Tibetan pigs from Tibet, Yunnan Tibetan pigs, and Gansu Tibetan pigs. This study aimed to explore population diversity, genetic structure and selection signals among Tibetan pigs in four Chinese national nature reserves. The results show that there is different observed heterozygosity among Tibetan pig populations (0.1957-0.1978). Ratio of runs of homozygosity (Froh) calculation of four Tibetan pig populations by runs of homozygosity (ROH) revealed the presence of inbreeding within the population (0.0336-0.0378). Analysis of the genetic structure demonstrated distinct population stratification among the four Tibetan pig populations, with each showing relatively independent evolutionary directions. Furthermore, Five methods (FST, Piratio, ROD, Tajima's D, XP-CLR) were used to artificially select evolutionary trajectories. The results mainly involved processes such as DNA repair, immune regulation, muscle fat deposition and adaptation to hypoxia. In conclusion, this study enhances our understanding of the genetic characteristics of Tibetan pig populations and provides a theoretical reference for the conservation of resources across different populations of Tibetan pigs.

Milk Lipid Regulation in Dairy Goats: A Comprehensive Review

The growth, development, and milk production traits of dairy goats, which are important sources of high-quality animal protein, are significantly influenced by a combination of genetic and environmental factors. It is imperative to identify key genetic loci that govern economically valuable traits in order to enhance breeding programs. Despite advancements in genomic technologies, there are still gaps in knowledge regarding the interplay between genetic factors and environmental influences, particularly in relation to the regulation of milk production and quality. Therefore, the aim of this paper was to synthesize advancements in the genetic and environmental factors affecting milk production and quality in dairy goats and identify key regulatory mechanisms. This review summarizes the recent progress on the identification of genes associated with milk production traits using whole-genome resequencing, the use of transcriptomic profiling to identify genes linked to milk production, the exploration of regulatory mechanisms of lipid metabolism in goat mammary epithelial cells, and the evaluation of the influence of nutritional factors on milk quality. A comprehensive understanding of these interactions is essential for enhancing breeding strategies and ensuring the sustainability of dairy goat farming. Future research should incorporate multi-omics approaches to unravel the intricate regulatory processes governing milk production and adapt practices to meet global demand while upholding economic and environmental sustainability.

Whole-genome resequencing of native and imported dairy goat identifies genes associated with productivity and immunity

Understanding the differences in genetic variation between local Chinese dairy goat breeds and imported breeds can help germplasm innovation and molecular breeding. However, the research is limited in this area. In this study, whole-genome resequencing data from 134 individuals of both local and imported dairy goat breeds were analyzed, and their differences in genomic genetic variation, genetic diversity, and population structure were subsequently identified. We also screened candidate genes associated with important traits of dairy goats such as milk production (STK3, GHR, PRELID3B), reproduction (ATP5E), growth and development (CTSZ, GHR), and immune function (CTSZ, NELFCD). Furthermore, we examined allele frequency distributions for the genes of interest and found significant differences between the two populations. This study provides valuable resources for the study of genetic diversity in dairy goats and lays the foundation for the selective breeding of dairy goats in the future.

Genetic diversity and selection signatures in Hainan black goats revealed by whole-genome sequencing data

Understanding the genetic characteristics of indigenous goat breeds is crucial for their conservation and breeding efforts. Hainan black goats, as a native breed of south China's tropical island province of Hainan, possess distinctive traits such as black hair, a moderate growth rate, good meat quality, and small body size. However, they exhibit exceptional resilience to rough feeding conditions, possess high-quality meat, and show remarkable resistance to stress and heat. In this study, we resequenced the whole genome of Hainan black goats to study the economic traits and genetic basis of these goats, we leveraged whole-genome sequencing data from 33 Hainan black goats to analyze single nucleotide polymorphism (SNP) density, Runs of homozygosity (ROH), Integrated Haplotype Score (iHS), effective population size (Ne), Nucleotide diversity Analysis (Pi) and selection characteristics. Our findings revealed that Hainan black goats harbor a substantial degree of genetic variation, with a total of 23 608 983 SNPs identified. Analysis of ROHs identified 53 710 segments, predominantly composed of short fragments, with inbreeding events mainly occurring in ancient ancestors, the estimates of inbreeding based on ROH in Hainan black goats typically exhibit moderate values ranging from 0.107 to 0.186. This is primarily attributed to significant declines in the effective population size over recent generations. Moreover, we identified 921 candidate genes within the intersection candidate region of ROH and iHS. Several of these genes are associated with crucial traits such as immunity (PTPRC, HYAL1, HYAL2, HYAL3, CENPE and PKN1), heat tolerance (GNG2, MAPK8, CAPN2, SLC1A1 and LEPR), meat quality (ACOX1, SSTR1, CAMK2B, PPP2CA and PGM1), cashmere production (AKT4, CHRM2, OXTR, AKT3, HMCN1 and CDK19), and stress resistance (TLR2, IFI44, ENPP1, STK3 and NFATC1). The presence of these genes may be attributed to the genetic adaptation of Hainan black goats to local climate conditions. The insights gained from this study provide valuable references and a solid foundation for the preservation, breeding, and utilization of Hainan black goats and their valuable genetic resources.

Genomic analysis uncovers novel candidate genes related to adaptation to tropical climates and milk production traits in native goats

BACKGROUND

Since domestication, both evolutionary forces and human selection have played crucial roles in producing adaptive and economic traits, resulting in animal breeds that have been selected for specific climates and different breeding goals. Pakistani goat breeds have acquired genomic adaptations to their native climate conditions, such as tropical and hot climates. In this study, using next-generation sequencing data, we aimed to assess the signatures of positive selection in three native Pakistani goats, known as milk production breeds, that have been well adapted to their local climate.

RESULTS

To explore the genomic relationship between studied goat populations and their population structure, whole genome sequence data from native goat populations in Pakistan (n = 26) was merged with available worldwide goat genomic data (n = 184), resulting in a total dataset of 210 individuals. The results showed a high genetic correlation between Pakistani goats and samples from North-East Asia. Across all populations analyzed, a higher linkage disequilibrium (LD) level (- 0.59) was found in the Pakistani goat group at a genomic distance of 1 Kb. Our findings from admixture analysis (K = 5 and K = 6) showed no evidence of shared genomic ancestry between Pakistani goats and other goat populations from Asia. The results from genomic selection analysis revealed several candidate genes related to adaptation to tropical/hot climates (such as; KITLG, HSPB9, HSP70, HSPA12B, and HSPA12B) and milk production related-traits (such as IGFBP3, LPL, LEPR, TSHR, and ACACA) in Pakistani native goat breeds.

CONCLUSIONS

The results from this study shed light on the structural variation in the DNA of the three native Pakistani goat breeds. Several candidate genes were discovered for adaptation to tropical/hot climates, immune responses, and milk production traits. The identified genes could be exploited in goat breeding programs to select efficient breeds for tropical/hot climate regions.

Runs of Homozygosity Detection and Selection Signature Analysis for Local Goat Breeds in Yunnan, China

Runs of Homozygosity (ROH) are continuous homozygous DNA segments in diploid genomes, which have been used to estimate the genetic diversity, inbreeding levels, and genes associated with specific traits in livestock. In this study, we analyzed the resequencing data from 10 local goat breeds in Yunnan province of China and five additional goat populations obtained from a public database. The ROH analysis revealed 21,029 ROH segments across the 15 populations, with an average length of 1.27 Mb, a pattern of ROH, and the assessment of the inbreeding coefficient indicating genetic diversity and varying levels of inbreeding. iHS (integrated haplotype score) was used to analyze high-frequency Single-Nucleotide Polymorphisms (SNPs) in ROH regions, specific genes related to economic traits such as coat color and weight variation. These candidate genes include OCA2 (OCA2 melanosomal transmembrane protein) and MLPH (melanophilin) associated with coat color, EPHA6 (EPH receptor A6) involved in litter size, CDKAL1 (CDK5 regulatory subunit associated protein 1 like 1) and POMC (proopiomelanocortin) linked to weight variation and some putative genes associated with high-altitude adaptability and immune. This study uncovers genetic diversity and inbreeding levels within local goat breeds in Yunnan province, China. The identification of specific genes associated with economic traits and adaptability provides actionable insights for utilization and conservation efforts.

Identification of genomic characteristics and selective signals in Guizhou black goat

BACKGROUND

Guizhou black goat is one of the indigenous black goat breeds in the southwest region of Guizhou, China, which is an ordinary goat for mutton production. They are characterized by moderate body size, black coat, favorite meat quality with tender meat and lower odor, and tolerance for cold and crude feed. However, little is known about the genetic characteristics or variations underlying their important economic traits.

RESULTS

Here, we resequenced the whole genome of Guizhou black goat from 30 unrelated individuals breeding in the five core farms. A total of 9,835,610 SNPs were detected, and 2,178,818 SNPs were identified specifically in this breed. The population structure analysis revealed that Guizhou black goat shared a common ancestry with Shaanbei white cashmere goat (0.146), Yunshang black goat (0.103), Iran indigenous goat (0.054), and Moroccan goat (0.002). However, Guizhou black goat showed relatively higher genetic diversity and a lower level of linkage disequilibrium than the other seven goat breeds by the analysis of the nucleotide diversity, linkage disequilibrium decay, and runs of homozygosity. Based on FST and θπ values, we identified 645, 813, and 804 selected regions between Guizhou black goat and Yunshang black goat, Iran indigenous goat, and cashmere goats. Combined with the results of XP-EHH, there were 286, 322, and 359 candidate genes, respectively. Functional annotation analysis revealed that these genes are potentially responsible for the immune response (e.g., CD28, CD274, IL1A, TLR2, and SLC25A31), humility-cold resistance (e.g., HBEGF, SOSTDC1, ARNT, COL4A1/2, and EP300), meat quality traits (e.g., CHUK, GAB2, PLAAT3, and EP300), growth (e.g., GAB2, DPYD, and CSF1), fertility (e.g., METTL15 and MEI1), and visual function (e.g., PANK2 and NMNAT2) in Guizhou black goat.

CONCLUSION

Our results indicated that Guizhou black goat had a high level of genomic diversity and a low level of linkage disequilibrium in the whole genome. Selection signatures were detected in the genomic regions that were mainly related to growth and development, meat quality, reproduction, disease resistance, and humidity-cold resistance in Guizhou black goat. These results would provide a basis for further resource protection and breeding improvement of this very local breed.

Genetic Diversity, Population Structure and Selection Signature in Begait Goats Revealed by Whole-Genome Sequencing

Goats belong to a group of animals called small ruminants and are critical sources of livelihood for rural people. Genomic sequencing can provide information ranging from basic knowledge about goat diversity and evolutionary processes that shape genomes to functional information about genes/genomic regions. In this study, we exploited a whole-genome sequencing data set to analyze the genetic diversity, population structure and selection signatures of 44 individuals belonging to 5 Ethiopian goat populations: 12 Aberegalle (AB), 5 Afar (AF), 11 Begait (BG), 12 Central highlands (CH) and 5 Meafure (MR) goats. Our results revealed the highest genetic diversity in the BG goat population compared to the other goat populations. The pairwise genetic differentiation (FST) among the populations varied and ranged from 0.011 to 0.182, with the closest pairwise value (0.003) observed between the AB and CH goats and a distant correlation (FST = 0.182) between the BG and AB goats, indicating low to moderate genetic differentiation. Phylogenetic tree, ADMIXTURE and principal component analyses revealed a classification of the five Ethiopian goat breeds in accordance with their geographic distribution. We also found three top genomic regions that were detected under selection on chromosomes 2, 5 and 13. Moreover, this study identified different candidate genes related to milk characteristics (GLYCAM1 and SRC), carcass (ZNF385B, BMP-7, PDE1B, PPP1R1A, FTO and MYOT) and adaptive and immune response genes (MAPK13, MAPK14, SCN7A, IL12A, EST1 DEFB116 and DEFB119). In conclusion, this information could be helpful for understanding the genetic diversity and population structure and selection scanning of these important indigenous goats for future genetic improvement and/or as an intervention mechanism.