About 80 percent of the sheep in the United States are raised in the western United States where extensive private and public ranges provide the bulk of the feed requirement. Only about 41 percent of the West's sheep producers have commercial scale operations of 50 head or more sheep, but they own nearly 93 percent of the region's sheep. About one-third of these commercial producers have specialized in sheep while two-thirds have diversified livestock operations. More than two-thirds operate as sole proprietors, while the rest have formed partnerships and family corporations. Many have substantial equity positions, which indicate past profitability. About one-fifth will likely be retiring in the next 10 years, which could result in many operations going out of sheep production. About half of the feed requirement for commercial sheep comes from private range, while public range supplies about one-fifth. Over half of the commercial sheep are grazed under the care of herders, usually on open (unfenced) range. Most lambing occurs in late winter and early spring. More commercial producers practice shed-lambing than range-lambing, but the number of sheep involved is less. The principal marketing problem is the few numbers of buyers bidding on lambs.