marbling [ˈmɑːblɪŋ]
n
the streaks of fat in lean meat
The longer a pen of beef cattle are on feed in the feedlot, the higher the chance they will grade higher on quality scores, but will have much lower yield grades (percentage of carcass lean to fat ratio). Feeding a high amount of cereal grains, such as corn or barley, will change the color of the carcass fat from a yellowish to a white, plus increase the chance of obtaining a higher quality grade according to the USDA. It can be risky to feed a cattle too much grain to increase marbling, because it can cause excessive flatulence. Cattle are ruminants; their stomachs are better at digesting grass, not grain. To increase marbling and rapidly increase weight gain, "the contemporary beef cow (sic) is being selected for the ability to eat large quantities of corn and efficiently convert it to protein without getting too sick."