Genomic Regions Associated with Sheep Resistance to Gastrointestinal Nematodes

Benavides, Magda Vieira; Sonstegard, Tad S.; Tassell, C. P. van

doi:10.1016/j.pt.2016.03.007

Cited by 49 publications

(49 citation statements)

References 77 publications

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“…The national flock peaked at about 56 million head in 1942 and dropped to 7 million by 2000[1]. However, religious, ethnic, and organic markets for lamb and sheep products have grown substantially in recent years[2].…”

Section: Introductionmentioning

confidence: 99%

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Whole genome structural analysis of Caribbean hair sheep reveals quantitative link to West African ancestry

et al. 2017

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Hair sheep of Caribbean origin have become an important part of the U.S. sheep industry. Their lack of wool eliminates a number of health concerns and drastically reduces the cost of production. More importantly, Caribbean hair sheep demonstrate robust production performance even in the presence of drug-resistant gastrointestinal nematodes, a rising concern to the industry. Despite the growing importance of hair sheep in the Americas their genetic origins have remained speculative. Prior to this report no genetic studies were able to identify a unique geographical origin of hair sheep in the New World. Our study clarifies the African and European ancestry of Caribbean hair sheep. Whole-genome structural analysis was conducted on four established breeds of hair sheep from the Caribbean region. Using breeds representing Africa and Europe we establish an objective measure indicating Caribbean hair sheep are derived from Iberian and West African origins. Caribbean hair sheep result from West African introgression into established ecotypes of Iberian descent. Genotypes from 47,750 autosomal single nucleotide polymorphism markers scored in 290 animals were used to characterize the population structure of the St. Croix, Barbados Blackbelly, Morada Nova, and Santa Ines. Principal components, admixture, and phylogenetic analyses results correlate with historical patterns of colonization and trade. These patterns support co-migration of these sheep with humans.

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Section: Introductionmentioning

confidence: 99%

“…Dense genotyping also provides a means of mapping desired traits to specific regions of the genome designated quantitative trait loci (QTL)[22]. This identifies not only phenotypes controlled by single genes, but complex traits produced by the interaction of many genes[1, 4, 23,24]. …”

Section: Introductionmentioning

confidence: 99%

Whole genome structural analysis of Caribbean hair sheep reveals quantitative link to West African ancestry

et al. 2017

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“…Fecal egg count (FEC) is used to measure resistance to gastrointestinal parasites in sheep, and the causal variants for FEC using a genome wide association study were found on chromosome 14 (linked to Nematodrius average animal effect) and chromosome 6 (Strongyles FEC at 16 weeks) [90]. Various other genes have been linked to host resistance to different gastrointestinal parasites (Haemonchus contortus, Teladorsagia circumcinta, and Trichostrongylus colubriformis) [91]. These genes were found on ovine chromosome 1, 3, 6 and 20 and are linked to the immune system, mucosal protection and hemostasis [91].…”

Section: Causal Variants Methods Used Referencesmentioning

confidence: 99%

“…Various other genes have been linked to host resistance to different gastrointestinal parasites (Haemonchus contortus, Teladorsagia circumcinta, and Trichostrongylus colubriformis) [91]. These genes were found on ovine chromosome 1, 3, 6 and 20 and are linked to the immune system, mucosal protection and hemostasis [91]. Genes that have been reported to influence carcass traits include callipage, myostatin and carwell genes [97,98].…”

Section: Causal Variants Methods Used Referencesmentioning

confidence: 99%

“…This serves as a backbone for genome wide association studies (GWAS) that can be used to associate phenotypes with causal variants [23,89]. Causal variants have been identified for various traits important for sustainability including reproduction [23], gastrointestinal parasite resistance [90,91], growth and meat production [92][93][94], wool traits [95] and adaptation in extreme environments [96] (Table 2). Table 2.…”

Section: Applying Genomics To Improve Traits Important For Sustainablmentioning

confidence: 99%

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Genetic Traits of Relevance to Sustainability of Smallholder Sheep Farming Systems in South Africa

et al. 2017

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Sustainable livestock production is important to ensure continuous availability of resources for future generations. Most smallholder livestock farming systems in developing countries have been perceived to be environmentally, socially and economically unsustainable. Farming with livestock that is robust and adaptable to harsh environments is important in developing countries especially in semi-arid and arid environments. This review discusses the different sheep farming systems employed by smallholder farmers and associated sustainability problems facing them. The review also gives an overview of sustainability indicators and limitations to the sustainability for the different smallholder sheep production systems in South Africa. It is argued that genetic diversity is important for sustainability and needs to be maintained in sheep for sustainable production and reproduction performance. The application of traditional breeding and genomics to ensure sustainable production is explored. Animal breeding approaches, specifically genomics can be applied to improve areas of environmental sustainability of smallholder sheep farming systems but must be targeted to the specific production environments, challenges, and opportunities of smallholder production. The genetic traits important for sustainability, the role of genomics in improving these traits and linking these genetic traits to different farming systems in South Africa are discussed.

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PCR-based genotyping of SNP markers in sheep

et al. 2018

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Single nucleotide polymorphisms (SNPs) are the main type of variation in genome, enabling them to be associated with traits of economic importance in livestock. Genome-wide association studies (GWAS) have led to the discovery of SNPs associated with desirable traits in sheep. However, in these studies, SNPs are genotyped by high-throughput methods in genome scale, which are expensive and require sophisticated equipment and analysis methods. Therefore, the goal of this study was to develop a reliable, rapid, and inexpensive polymerase chain reaction (PCR)-based method to genotype a medium number of animals for a few candidate SNPs previously associated with desirable phenotypes in sheep by GWAS, using markers associated with gastrointestinal nematode resistance as a model. DNA extracted from white-blood cells of 150 sheep was submitted to PCR amplification followed by agarose gel electrophoresis and determination of banding pattern. Tetra-primer ARMS-PCR was successfully optimized after changes in annealing temperature; annealing and extension times; concentration of MgCl and DNA; ratios of inner, outer, forward and reverse primer; and addition of adjuvants, for genotyping the OAR2_14765360, OAR6_81718546, OAR11_62887032, and OAR12_69606944 SNPs in sheep. An extensive optimization of tetra-primer ARMS-PCR resulted in a suitable, simple, cost-effective PCR-based method of genotyping four SNP markers previously detected by chip arrays.

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Genomic Regions Associated with Sheep Resistance to Gastrointestinal Nematodes

Cited by 49 publications

References 77 publications

Whole genome structural analysis of Caribbean hair sheep reveals quantitative link to West African ancestry

Whole genome structural analysis of Caribbean hair sheep reveals quantitative link to West African ancestry

Genetic Traits of Relevance to Sustainability of Smallholder Sheep Farming Systems in South Africa

PCR-based genotyping of SNP markers in sheep

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