2012 WORLD HOLSTEIN CONFERENCE - Dansk Holstein

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SESSION 1: THE GENOMIC REVOLUTIONWhat’s Coming Next in GenomicsBEN HAYS (AUSTRALIA)Dr. Ben Hayes has a wide ranging career designing geneticimprovement programs for beef cattle, sheep and Atlantic salmon.However, his focus for the past five years has been the development ofgenomic selection methods, particularly for dairy cattle. Recent workhas addressed the challenges of optimal breeding program designwith genomic selection, incorporating whole genome sequenceinformation into genomic selection in the 1000 bull genomes project,as well as improving feed conversion of dairy cattle. Dr. Hayescurrently leads the dairy cattle genetics program in the Dairy FuturesCooperative Research Centre.Genomic breeding values are now widely used for selection of bulls, and heifers, in dairy industries around the world.The are three major challenges for the future 1) improving the reliability of genomic breeding values 2) reducing thecost of genomic breeding values and 3) expanding the list of traits for which genomic breeding values are available for,to include traits which are likely to be important in the future such as feed conversion efficiency and methane emissionlevels.The first challenge could be met by both increasing the size of the reference populations used to estimate DNA varianteffects (eg more bulls and cows genotyped with excellent records), and moving from DNA markers (eg SNP chips) to fullgenome sequence. Unfortunately the cost of sequencing is such that it is unlikely that the entire reference populationwill be sequenced. An alternative strategy is to sequence key ancestor bulls of the current Holstein populations (usuallythe “legends” of the breed), then impute the genotypes for the sequence variants into much larger reference sets withphenotypes and SNP chip genotypes. The 1000 Bull Genomes Project is an international project with precisely this aim.If the cost of obtaining genomic breeding values (including DNA marker genotyping) could be significantly reduced,they could be more widely used to select heifer replacements. This would have the great advantage that hundredsof thousands of genotyped heifers would eventually become part of the reference population, which would in turnimprove the reliability of the genomic breeding values. New technologies to reduce cost of genomic breeding valuesare discussed.Finally, genomic breeding values offer the opportunity to select for traits which contribute to profit, but would otherwisebe prohibitively expensive to measure. Feed conversion efficiency (eg the efficiency of turning feed into milk) is anexcellent example. Australian and international progress toward feed conversion efficiency genomic breeding valuesare described.10
SESSION 1: THE GENOMIC REVOLUTIONInbreeding Using Genomics & How It Can HelpFLAVIO SCHENKEL (CANADA)Dr. Schenkel holds a number of degrees including a Ph.D. in AnimalBreeding from the Department of Animal and Poultry Science,University of Guelph. He also holds a B.Sc. and M.Sc. from FederalUniversity of Rio Grande do Sul, Brazil. In his academic activities,Dr. Schenkel has published 51 refereed papers, 57 short papers inconferences, and more than 98 scientific abstracts and technicalarticles. His main academic interests are in the genetic improvementof livestock including estimation of genetic and environmentalparameters required for genetic evaluations; genetic evaluation andimprovement of livestock through statistical modeling; detection ofquantitative trait loci; combining molecular and quantitative geneticinformation into genetic evaluations; genomically enhanced geneticevaluations and selection; and conservation of genetic variability and diversity.Inbreeding is a current topic in Holstein breeding mainly because breeding programs around the world arefocussed on a limited number of Holstein bulls to be used as sires of sons. Genomic selection has been successfullyimplemented in Holstein cattle evaluation in several countries worldwide. One of the challenges that still remainsafter its implementation is how to optimally manage inbreeding. Studies suggest that genomic selection will resultin a lower rate of inbreeding per generation, a consequence of increasing selection emphasis on Mendelian samplingcomponent of the breeding value rather than on the part derived from relatives. This allows differentiate full-sibsthat have different Mendelian sampling values, therefore being less likely to co-select them for breeding than if theselection decision was made just based on their parents’ breeding values. Nevertheless, because genomic evaluation isavailable early in the animal’s life, the corresponding decrease in generation interval might actually result in an increasein inbreeding per year. Genomic information offers, however, an excellent opportunity to examine inbreeding andgenetic diversity at the genome level, so that the actual levels of inbreeding and relationship between individualscan be more accurately calculated and predicted. Simulation studies show that selection schemes (e.g., optimumcontribution) and mating strategies (e.g., minimum co-ancestry) might be even more valuable to control inbreedingunder genomic selection than before. The development of strategies to better use genomic information aiming tomake fast genetic progress whilst managing inbreeding and diversity levels seems currently needed.11
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2012 WORLD HOLSTEIN CONFERENCE - Dansk Holstein

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