Animal Breeding & Genetics Symposium II
By Anne Zinn
On the morning of July 21, 2020, viewers gathered virtually for the second Animal Breeding and Genetics Symposium as part of the ASAS-CSAS-WSASAS Virtual Annual Meeting. The session was led by Dr. Ignacy Misztal, Professor at the University of Georgia, and focused on changes in genomic selection, genome-wide association studies, and fluctuations in genomic evaluations. To begin the session, Dr. Miguel Toro Ibáñez (Universidad Politécnica de Madrid) reviewed the benefits and challenges when estimating genetic parameters from molecular data, and then Dr. Misztal continued the discussion by presenting on parameter estimation under genomic selection. Dr. Misztal identified the challenges faced when using parameter estimation vs. genomic selection, how the methods could be used together, and where new, more efficient tools would be useful to advance the field.
The next two speakers focused their presentations on genome-wide association studies. First, Dr. I Ma, Associate Professor at the University of Maryland, described the various methods of genome-wide association studies and their specific applications within dairy cattle. The goal of genome-wide association studies is to uncover genomic regions that harbor variants that explain a large proportion of the phenotypic variance, which would assist in discovering and studying causative variants.Juan Steibel, Associate Professor at Michigan State University, then shared how genome-wide association studies could be used within complex models accounting for populations structure with genomic best linear unbiased prediction (GBLUP) and single-step GBLUP (ssGBLUP). Steibel shared that there are several methods that have been successfully applied for embedding genome-wide association studies into genomic prediction models, but most methods do not use formal hypothesis testing. Steibel went on to share the methodological details of a method for performing formal hypothesis testing for GWAS in GBLUP models, which could potentially produce several useful extensions such as testing multiple markers at once, testing pleiotropic effects and testing association of social genetic effects.
To conclude the session, Dr. Daniela Lourenco, Assistant Professor at the University of Georgia, presented on the increased fluctuations of genetic evaluations with genomic information. Dr. Lourenco explained that with the adoption of genomic evaluations by the livestock industry and the accumulation of genotypes, changes in genomic estimated breeding value in subsequent evaluations are being frequently reported, which has led to questions about why such changes happen; Dr. Lourenco answered that the main cause is the increase in connectivity among animals. A conclusion of the research described is that making selection decisions based on groups of animals with high average accuracy instead of individual animals may help to offset the impact of fluctuations in genomic evaluations.
The full symposium recording can be found on the ASAS-CSAS-WSASAS Virtual Meeting website.