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Whole genome selection and the 2000 bull project at USMARC Larry Kuehn Research Geneticist
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DNA Technology Genome is highly complex Difficult to understand, manipulate Historically, oversold to producers Need patience, research support, partnerships
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Definitions Genome is the whole set of DNA Genetic Markers track regions of the genome –May be linked/explain phenotypes we observe A SNP is a type of genetic marker –Single Nucleotide Polymorphism A Genotype is any pair of markers/marker groups
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Whole Genome Selection (WGS) Use genotypes of thousands of genetic markers, like SNP, to predict breeding values (EPDs) Like marker sets for traits being offered now but with much more density Genetic differences in DNA that cause phenotypic differences likely close to many markers As of now unproven (but preliminary analyses look promising)
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Problem: Whole-genome selection seems to be big leap technology that needs to either be implemented in a big way or not at all. Early adopters are likely to receive little benefit until a critical mass of influential and extensively phenotyped animals is tested and the data is analyzed jointly through NCE.
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Whole Genome Selection So is now the time? –We think so! –Multiple reasons why the time is right
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Illumina Infinium Bovine BeadChip ~ 50,000 SNP markers across the bovine genome -On average SNP every >60,000 base pair - Discovery SNP includes many breeds BARC (ARS) USMARC University of Missouri University of Alberta Reason 1: Technology
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Reason 2: Data/Cattle About 3,000 hd of pedigreed animals with extensive phenotypes at USMARC genotyped using the 50K chip Primarily descendants of Germplasm Evaluation (GPE) Cycle VII –Angus, Hereford, Red Angus –Charolais, Gelbvieh, Simmental, Limousin
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Reason 2: Data/Cattle Some phenotypes difficult to measure in industry setting –Feed intake –Carcass data –Slice shear force –Structure –Puberty and productivity –Disease diagnostic records
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Reason 3: People Collaborative effort between researchers and breed representatives to implement WGS for the industry
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2000 Bull Project Collaborative effort DNA samples from influential or upcoming bulls in 16 most prominent breeds with a genetic evaluation –Running on 50K chip Extensively phenotyped animals from USMARC used as training data set –Establish relationships of markers to phenotypes and use results to predict potential of 2000 industry bulls
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2000 Bull Project Objectives: –Extend genetic predictions from USMARC phenotypes to industry bulls EPDs developed and delivered to breed associations (they decide use) Hopefully leads to further bull genotyping –Validate the effectiveness of WGS using EPDs from the 2000 bulls relative to USMARC data on common traits (e.g., weaning weight) –Improve accuracy of EPDs for common traits
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2000 Bull Project Breed associations responsible for selecting sires –High accuracy sires (verify the process) –Influential sires (greater gain from novel traits) Number of bulls from each breed dependent on breed size –Maximum of 400 sires from largest breed
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Potential pitfalls We don’t know the process of WGS will work May need more than 50,000 markers Need to develop complex computational methods –1992-2006:1.7 million genotypes at USMARC –2007-2008:~300 million genotypes expected from chip results
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Potential looks good Simulated accuracy of genetic prediction: SimulatedEPDWhole Genome Sires71%80% Progeny with no records 41%69% Unrelated with no records 0%55%
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SNP associations Birth Weight Weaning Weight Milk Postweaning gain Ribeye area Marbling score
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Contributors Bovine SNP Consortium -- ARS, BARC -- U. Missouri -- U. Alberta -- ARS, USMARC USMARC -- Tim Smith -- John Keele -- Mark Allan -- Warren Snelling -- Mark Thallman -- Gary Bennett -- Larry Kuehn -- Tara McDaneld ARS NPS -- Steve Kappes NBCEC Breed Associations
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