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. 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. This article incorporates public domain material from the Congressional Research Service document 'Report for Congress: Agriculture: A Glossary of Terms, Programs, and Laws, 2005 Edition' by Jasper Womach.