Growing out and fattening cattle in a feedlot In an on-farm feedlot, the farmer fattens young cattle in pens or large paddocks, using bought-in or home-grown feed. The livestock can be self-produced or bought in. Commercial feedlots are the major finishers of beef. The feedlot owner, often a speculator, buys animals specifically for the feedlot. Ownership of the animals and the risk associated with feeding them becomes his responsibility. In a custom feedlot, the feedlot operator does not buy in