During her PhD studies, Xiangyu Guo investigated different approaches to improve genomic prediction and genome wide association study (GWAS) for litter size and piglet mortality in pig. Litter size and piglet mortality are important traits in pig breeding. The traits are relatively difficult to improve by traditional selection since the traits have low heritability and animals are selected before they have own records. Using genomic data, animals can be selected accurately early in life, which is especially beneficial for genetic improvement of complex traits such as reproduction traits.

In her dissertation, first, genomic prediction is improved by using a single-step BLUP method which utilizes information from genotyped as well as non-genotyped individuals simultaneously. Results show that genomic estimated breeding values are more precise than traditional estimated breeding values and both the estimates of genotyped and non-genotyped animals benefit mutually from each other. Second, a Bayesian mixture model and a novel method for quantitative trait loci (QTL) region detection were proposed for GWAS. Fifteen important QTL regions are identified and they provide better understanding of litter size and piglet mortality traits. Finally, results show that models including dominance genetic effects improve accuracy of genomic prediction.

The PhD degree was completed at the Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Science and Technology, Aarhus University.

This résumé was prepared by the PhD student.

Time: Monday 29 February 2016 at 13.00
Place: Lecture Theatre, Aarhus University Foulum, Blichers Allé 20, 8830 Tjele
Title of dissertation: Genomic prediction and GWAS for reproduction traits in Danish pigs
Contact information: Xiangyu Guo, xiangyu.guo@mbg.au.dk, +45 8715 4987
Members of the assessment committee:
Professor Haja Kadarmideen, Department of Veterinary Clinical and Animal Sciences, University of Copenhagen
Professor Pekka Uimari, Department of Agricultural Sciences, University of Helsinki
Associate Professor Bernt Guldbrandtsen (chair), Department of Molecular Biology and Genetics, Aarhus University
Main supervisors:
Senior Scientist Guosheng Su, Department of Molecular Biology and Genetics, Aarhus University
Co-supervisors:
Professor Mogens Sandø Lund, Department of Molecular Biology and Genetics, Aarhus University
Senior Scientist Ole Fredslund Christensen, Department of Molecular Biology and Genetics, Aarhus University
Professor Yachun Wang, Department of Animal Science and Technology, China Agricultural University
Language: The dissertation will be defended in English

The defence is public.
The dissertation is available for reading at the Graduate School of Science and Technology/GSST, Ny Munkegade 120, building 1520, rooms 128-134, 8000 Aarhus C.