If a live animal weighs more, you would expect it to have more total muscle than a lighter weight animal. The same is true for carcasses. If a carcass does not have as much muscling as we would expect from an average animal of that weight, it makes the yield grade less desirable. On the other hand, if a carcass has more muscling than average for that weight, it helps the yield grade. Percentage of KPH measures the amount of internal fat an animal has.
All animals have some fat surrounding their internal organs such as the liver and heart.
The less of this type of fat a carcass has, the better it is for the yield grade. The pork carcass contest is ranked on percent lean of the carcass. This is fat that is found within the muscles and contributes to the juiciness and flavor of pork. The measurements of 10th rib fat and loin eye area were obtained from ultrasound scanning of the hogs at check in. By using ultrasound, fat thickness and loin eye area are estimated to the nearest hundredth of an inch and square inch.