Submitted to: Beef Improvement Federation Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/12/2009
Publication Date: 4/13/2009
Citation: Kuehn, L.A., Keele, J.W., Thallman, R.M. 2009. Estimation of Current Breed Differences in Multibreed Genetic Evaluations Using Quantitative and Molecular Approaches. Proc., Beef Improvement Federation 9th Genetic Prediction Workshop, Kansas City, MO. December 8-10, 2008. pp. 49-60. Interpretive Summary:
Technical Abstract: The objectives of this presentation were to review methods used in multibreed approaches in national cattle evaluation, suggest guidelines for utilizing information for research estimates of breed differences, describe the design of the multibreed research program (germplasm evaluation; GPE) at the U.S. Meat Animal Research Center, and demonstrate some results and potential for molecular identification of breeds using high-density marker arrays. Methodology exists to compare cattle for their genetic potential as parents across breeds. However, the parameters required in this methodology cannot be accurately estimated from field data. Therefore, these parameters, such as estimates of breed differences and heterosis must be obtained from research data. Statistical models have been developed to incorporate research estimates of breed differences into multibreed cattle evaluations. Literature estimates of breed differences are prevalent, but it is difficult to determine how to weigh multiple sources of information. Research studies vary in the quality of breed sampling and generally assume that breed differences are constant rather than changing due to varying levels of selection among breeds. We proposed adjusting the estimates of breed differences to the current level of breeding values for each breed using current EPDs supplied by the breed associations. This is the basis for breed differences as predicted for yearly across-breed EPD adjustment factors. The GPE program at the U.S. Meat Animal Research Center will continue to evolve to improve the accuracy of estimates of breed differences and heterosis. Molecular tools that predict breed composition of crossbred progeny may facilitate the use of these differences in industry field data.