You mentioned angus cattle. Here is a description of the AAA epd's.
www.angus.org
It is important to know the units for the epd numbers. On weight based epd's, the units are pounds. On Calving Ease Direct, the units are percent.
The document says: "
Calving Ease Direct (CED), is expressed as a difference in percentage of unassisted births, with a higher value indicating greater calving ease in first-calf heifers. It predicts the average difference in ease with which a sire's calves will be born when he is bred to first-calf heifers."
Higher value indicates greater calving ease than a low value. You will have to decide if more calving ease is "best or not". Many would recommend avoiding extremes in all epd's. Most would probably say that more CED, more WW, more YW, more milk are "better". But that is not always true unless you need "more" of that trait. At some point, "more" might/will become bad. More milk may mean hard keeping inefficient cows that do not last. Beef cows that milk like a holstein are not "best". "Best" numbers for terminal (sell all calves for beef) situations will be different than "best" numbers where replacements (breeding stock) are retained.
Marbling epd
units are USDA marbling score. Higher number means more marbling.
Remember that there is no direct calculation between an epd number and the actual value of the parameter. Bull A with a CED of 5 and Bull B with a CED of 15 is a difference of 10. That indicates that the % of first calf heifers bred to Bull B that require assistance should be about 10% less than the % of first calf heifers requiring assistance when bred to Bull A. What % of the heifers will require assistance? No information in the epd's to answer the question. If the heifers have small pelvic areas and are mud fat, then lots of assistance required for both bull's calves. Estimated to be 10% more for Bull A than bull B. If the heifers have large pelvic areas, plenty of size/growth/frame without being fat, then expect very few to require any assistance. Again, don't try to turn an epd value into a prediction of absolute values of the units.
Here are the AAA averages for epd's.
www.angus.org
Here is some info on carcass epd's.
Epd's with an I indicate an interim value until the next complete update/recalculation of the registry epd's. Explained here:
www.angus.org
GoWyo has explained epd accuracy and percentiles. Accuracies are just as important as the epd numbers. Percentiles are an easy way to rank without having to remember average values. 50 percentile is breed average. 99 is bottom of breed. 1 is top of breed.
Lots of information on the web. Plan to spend some time reading, researching, thinking and pondering. Some traits are inversely related. You increase one and you decrease another. Make too much gain in one area and lose too much in another. Don't chase numbers for the sake of numbers. Don't chase extremes.
