Ultrasound measures for 12-13th rib fat thickness, rump fat thickness, ribeye area and % intramuscular fat have been collected on more than 27,000 yearling Angus bulls and more than 7,000 developing heifers as part of a two-year research program with the American Angus Association. The effects of the age of the cow producing the calf and the age of the calf at scanning time are significant and must be accounted for through adjustments to the actual ultrasound measures before breeders can use the information to compare animals within contemporary groups.