Wiktionary
fed cattle
n. (context agriculture English) cattle leaving a feedlot, after fattening on a concentrated ration, that are ready to be sold to a packinghouse for slaughter.
Wikipedia
Fed cattle
Fed cattle refers to animals leaving a feedlot, after fattening on a concentrated ration, that are ready to be sold to a packing plant for slaughter. Beef cattle are typically sold to packers at about 1,100 pounds, which yields a carcass weight of about 660 pounds.