The discussion of how to utilize breed association expected progeny differences (EPDs) by setting individual goals requires that producers understand how bulls are positioned within the breed association's data set.
For example, if a producer is looking at a Simmental bull, then go to the American Simmental Association's website at http://simmental.org/site/ and click on the "Industrial Science/Tech Advancement" tab. From there, hover on the "Genetic Prediction (EPD)" box and scroll down to the "% Tables/Breed Avg." tab.
Click on the box and select the desired cattle type.
The Dickinson Research Extension Center is using purebred Simmentals, so we would click on "Purebred Simmentals" to see the 2014 purebred Simmental percentile table, then print the table. The table for other breeds will be about the same but may have different labeling on their respective websites and tables.
Step two is to get a colored highlighter pen and prepare to decide what level of performance one wants to select when buying a bull. For example, one can decide to ask to see the EPD value rankings for a particular trait much like one would ask to see the miles per gallon rankings for a specific car model to compare with other models.
A simple way to deal with the table is to decide on what level of performance one wants to shop for. For example, the center desires that the Simmental bulls simply rank in the upper 50 percent of the breed for the desired traits.
Therefore, locate 50 percent on the left-hand side of the percentile table and read across the table to determine the EPD value for each trait printed in the sire summary that would rank a bull at the 50th percentile within the breed. It sounds complicated but it really isn't.
Now take the colored highlighter pen and draw a line across the table at the 50 percent line. Now you have highlighted the EPD value needed to rank a bull at the desired 50th percentile within the breed. By looking at the numbers above the line, one knows the EPD values of the bulls ranked within the upper 50th percentile. So the performance of the bulls is unveiled, which is what we are searching for. As the center buys bulls, in this case Simmental bulls, the center uses the same process.
The center focuses on five traits within the Simmental breed - birth weight, weaning weight, yearling weight, marbling score and rib-eye area - and sets a goal that the average value for herd sire EPDs should meet or exceed average EPD values.
Using the process described above, the purebred Simmental breed average (50th percentile) birth weight is 2.2 pounds, weaning weight is 64.2 pounds, yearling weight is 93.2 pounds, marbling score is 0.13 and rib-eye area is 0.76 square inch.