Today’s bull buyer is offered a great deal of information, and it can be confusing. It is not unusual for bull sale catalogs to print any or all of the following: actual birth weight, birth weight ratio, calving ease score, birth weight EPD, and calving ease EPD. So which one do you use? It depends upon which ones are offered for your evaluation. The research data would support that using the most direct genetic evaluation possible is best for your selection process. So in this case, your best information piece would be calving ease EPD. This genetic evaluation takes into account the bull’s actual calving ease and his parents’ data and also incorporates birth weight information into the calving ease EPD calculation. It has been seen over and over again that not all low birth weight bulls are calving ease sires and also that excellent calving ease sires are not always low birth weight sires. Indeed, some calving ease sires are moderate in their birth weights.
If you do not have the calving ease EPD available, you might go next to the birth weight EPD. It is the next best indicator trait for calving ease in bulls. A distant third would be birth weight ratio. Why birth weight ratio instead of actual birth weight? Because it compares the birth weight within a true contemporary group. For instance, an 80-pound birth weight from a first-calf heifer compared to an 80-pound birth weight in a set of mature cows could be many ratio points apart.