February 2015 | www.GELBVIEH.org
In this Issue: Creating UserFriendly Replacement Heifers Are You Ready for Calving? Perrymann Banking on Balancer® Bull Buying Decisions in the Good Times Buying Late Bred Cows and Their Potential for Additional Revenue
What is the Value in Buying a Bull with GenomicEnhanced EPDs? Improvements in Expected Progeny Difference (EPD) accuracy has historically been driven by phenotypic record collection directly on the trait of interest (e.g. marbling score, calving ease) or on indicator traits (e.g. ultrasound measures, birth weight). By Matt Spangler, Ph.D., University of Nebraska-Lincoln CONSEQUENTLY, ACCURACY values for yearling bulls purchased by commercial producers will be low. In most cases only the bull’s pedigree information and own performance records for traits observed before sale day will be included in his EPD calculations. No daughters will have been produced at that time, so only pedigree estimate or interim EPDs will be available for maternal traits, and these EPD have low accuracies. Additional information from another source is needed to improve the accuracy of the EPDs of yearling bulls. Results from genomic tests, often referred to as Molecular Breeding Values (MBV), have proven to be a valuable source of added information for breeds that have capitalized on the technology and included them into EPDs. Genomic tests evolve as quickly as new cell phones and the U.S. beef industry has witnessed considerable evolution in terms of the genomic tests
available in the marketplace. The underlying question commonly asked by producers is “Do genomic tests work?” It is critical to understand that this is a somewhat ambiguous question and not simply answered with a yes or no. The important question to ask is “How well do genomic tests work?”, and the answer to that question is related to how much of the genetic variation the genomic test explains. The benefit, or the increase in EPD accuracy, will be dependent upon the proportion of genetic variation (%GV) explained by a given genomic test. (See accompanying article on page 12) A very powerful genomic test that explains close to half of the genetic differences between animals is, by itself, limited to a BIF accuracy of 0.29. Consequently, MBVs should not be thought of as a separate independent predictor Continued on page 10
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