Culpeper Senior Bull Sale Catalog 2025

ECONOMIC INDEXES FOR BULL SELECTION

Scott P. Greiner Extension Animal Scientist - Virginia Tech Bull selection is the key to genetic progress. A challenge to bull selection is that there are many traits which are economically relevant to the beef enterprise- ranging from reproduction, calving ease, growth traits, maternal traits, and carcass merit. The beef industry has made strong investments to identify and develop prediction tools in the form of EPDs for these traits. Additionally, EPDs are also available for a number of additional traits such as foot soundness, hair shedding, efficiency measures, and others. Collectively, there may be in excess of 20 or more traits for which EPDs are available. While this large number of EPDs provides opportunity for genetic improvement across many traits, identification of which EPDs are most relevant and balancing them in a selection scheme can be challenging. Furthermore, prioritizing and placing proper economic weighting on each relevant trait further complicates selection. To address this, multi-trait selection indexes have been developed which allow for selection for several traits simultaneously. For each trait contained in the index, both genetic and economic values are considered, resulting in a comprehensive genetic prediction value that represents overall economic merit of the animal. Indexes provide simplicity and convenience to selection decisions by allowing for selection based on one index EPD value rather than several individual component EPDs. As a result of assigning economic weightings to the component EPDs, indexes are expressed in economic terms, meaning they predict differences in progeny performance in dollars rather than in pounds or other performance measures. This is accomplished by using a set of assumptions which impact estimated revenue and expenses for the traits included in the index. A number of selection indexes have been developed by beef breed associations. These indexes can be catego rized as maternal, terminal, or combination of both. See pages 2-3 of this catalog for a listing and short definition of each index EPD. Utilizing index EPDs in bull selection is very similar to using individual trait EPDs, the difference between animals is of most importance. For example, a $10 difference in Angus $M value between two bulls would indicate an average of $10 difference in future progeny profitability from conception through weaning. Indexes facilitate simultaneous improvement in a suite of traits known to impact a selection goal. For example, Angus $M includes traits relevant to cow-calf producers selling calves at weaning and keeping their own replace ments. These traits include calving ease direct, calving ease maternal, weaning weight, milk, heifer pregnancy, docility, mature cow weight, claw set and foot angle. As a result of the economic weightings used in the calculation of the index, index EPDs help optimize selection. Using $M for example, there is an added cost for more milk and growth, and mature size. Likewise, there is potential added revenue through pounds of weaning weight and higher fertility. The index accounts for all this, which is very challenging to do arbitrarily through simply evaluating individual trait EPDs. As a result, the maternal indexes (Angus $M, Gelbvieh MPI, Hereford BMI, Simmental API, etc.) are very useful tools for cow-calf producers marketing calves at or around weaning. In summary, index EPDs are a valuable tool to enhance balanced-trait selection. They predict the impact of genetic selection to enhance production output while accounting for costs associated with such production. Incorporating these indexes as a component of bull selection schemes is therefore warranted.

34 Performance Tested Bull Sale // Saturday, December 13, 2025