During the last 20 years there has been a marked change in the type of hogs from the short-legged, wide-bodied or "hot-blood" type to a longer, somewhat more narrow-bodied, "leggier" type. For development of size in hogs they must have (1) length and depth of body, (2) length of leg, and (3) large but not coarse bones. The long-bodied rather "leggy" pig grows rapidly and makes the larger hog. While the modern hog is still a lard hog, it is not as thick and broad as were its predecessors. It is logical to assume that the hog of the future will be required to make his gains more largely in growth on cheap roughages and less in fat on heavy grain feeding . It must also be noted that the hog which makes its gain by putting on a thick layer of fat probably will show a loss to the producer, while the hog which makes its gains by increasing its muscles will show a profit because it costs less to produce lean meat than it does fat. There is no demand on the market for the ultra-fat hog because lard is worth less after it is put in the pad than the packer pays for it on the hog; neither does the present-day consumer desire fat on meat purchased.
Smith, Harry H., "Circular No. 90 - Swine Production in Utah" (1930). UAES Circulars. Paper 79.