The book of abstracts is available. - Poznań

14 th QTL-MAS Workshop, Poznań University of Life Sciences, Poland 2010Genomic estimated breeding values and QTL positions: Common dataset ofQTL-MAS 2010 WorkshopX. Sun 1* , J. C. M. Dekkers 11 Department of Animal Science and Center for Integrated Animal Genomics, Iowa State University, Ames, Iowa50011*Presenting author: Xiaochen Sun, email: xsun1120@iastate.eduWe used a linear model with sex as fixed effects and random SNP effects to fit the datasetprovided by QTL-MAS 2010 Workshop and applied Bayesian analysis to obtain genomicestimated breeding values (GEBVs) and QTL positions.GEBV of each individual in Generation 5 was the sum of genetic effects of all SNPs itcarried, where effects of SNPs were estimated from phenotypic and genotypic records in thefirst four generations. The accuracy of our Bayesian method was evaluated by the correlationof phenotypes of individuals in the fourth generation with their GEBVs and divided by thesquare root of estimated heritability from REML, which is equivalent to the correlation ofGEBVs with true breeding values. The accuracy estimated this way could be as high as 0.8.However, since the individuals in the fifth generation did not have phenotypic records, theaccuracy of their GEBVs was not available.The bins spanning every 10 adjacent SNPs that explained genetic variances higher than apredefined threshold were selected as candidate genome regions containing QTLs. Withineach bin, the SNP explaining the highest genetic variance was used as the position of QTL.To set a threshold for genetic variances of bins, we simulated genotypes without QTL forindividuals in the first four generations using the same pedigree and SNP panel as thecommon dataset. Simulated SNP effects and genetic variances of bins were estimated fromsimulated genotypes and original phenotypes using the same Bayesian method. The thresholdof certain significance level was determined from the distribution of genetic variancesexplained by the bins across the whole genome. Since the threshold was arbitrary, we reporteda primary QTL list together with a secondary list, where the threshold of the former wasstringent and the latter more liberal.46