The growth of each component was estimated based on the liveweight growth curves and the body component to liveweight functions. Feed conversion and lean feed conversion curves were estimated from the feed intake and either liveweight or fat-free lean growth curves. Growth rate increases as liveweight increases, reaches a plateau, and then slowly declines after 200 lb. Feed intake increases linearly from 40 to 140 lb. After 140 lb, feed intake increases more slowly.
Barrows have both higher daily growth rates and feed intakes than gilts.
Protein accretion includes the protein in all body components including the head, carcass, visceral organs, feet, skin and bone. Carcass fat-free lean is the total dissected carcass muscle tissue minus the fat contained within the dissected muscle. The growth curves for lean gain and protein accretion are similar. Muscular pigs have a higher ratio of lean gain to protein accretion than less muscular pigs. Prediction equations for fat-free lean place more emphasis on loin eye area measurements than the empty body protein accretion prediction equations.