OKLAHOMA CITY (AP) — Oklahoma National Stockyards officials say nearly 13,000 head of cattle were sold at the Oklahoma National Stockyards this week — an increase of more than 50 percent over the 8,000 head normally sold at this time of year.

The stockyard in Oklahoma City is the largest cattle market in the nation.

Stockyards President Rob Fisher says the reason for the increase is the ongoing drought that's dried up water, leaving a scarcity of hay and grass to feed the herds. He tells The Journal Record that ranchers can't afford to buy hay and have nothing to feed the cattle.

The U.S. Drought Monitor last Thursday rated the drought as severe to extreme through central Oklahoma and exceptional in the western third of the state. The monitor is updated each Thursday.