SCIENCE “Defensins: Their Impact on How Genomics and EPD Projections Can Make a Serious Positive Contribution to Your Operation’s Bottom Line” by W.E. Julien, PhD, DVM. CEO of Anova BioSciences
Over the last few years, several articles have been published in “American Beef Producer’ that have focused on the creation of an operation’s positive bottom line through the strategic use of EPD and Genomics projections in cow/calf management. Two such articles, (Expected Progeny Differences by Randie Cuthbertson-Aug.‘21,p.36; and Time to Implement Single Trait Selection by Chip Kemp-May/June ‘21,p.8) are well worth your time to read again, and if you happened to have missed them, please do yourself a favor, take the time and look them up. In the August 2021 issue, Dr. Cuthbertson, has put together a tutorial on the hows, whys and what for‘s of EPD predictions and the role genomics testing plays in those predictions. Every calf has the genetic propensity to express a performance trait. However, expression of that trait is dependent not only on the presence of that trait but the environment that will impact the success or failure of its expression. Genomics testing provides the basis for a scientific best guess of how an individual will succeed (or fail) to meet life’s challenges. However, as a 50
selection tool, genomics does have some limitations. One example is the already mentioned impact of environment on gene expression. As the environment is not something that is inherent, genomics really defines the success (or failure) of that one individual, not his or her offspring. The most accurate interpretation of genomics testing results may come through the simultaneous calculation and application of EPDs. As genomics testing is driven by algorithms and mathematical models that arrive at a result, so too do EPDs, the difference being that the EPD models were developed to focus on the minimalization of variables that could impact interpretation of the genomic data (the environment is one excellent example). With EPDs, one individual can be compared to many others of similar age, sex, and under a variety of conditions, both good and bad, that could impact performance. This and its variants (predicted difference in dairy for example) have proven themselves over the years to be valuable tools in making progress, but EPDs also have their limitations. Chip Kemp points
American Beef Producer
February 2022
