(Recasts with wheat ending mixed, adds closing prices)
CHICAGO, Nov 8 (Reuters) - U.S. winter wheat futures ended mixed on Wednesday while soybeans and corn closed slightly higher as traders squared positions ahead of a monthly U.S. Department of Agriculture crop supply and demand report due out on Thursday, traders said.
Short covering buoyed corn and wheat late in the day, offsetting earlier declines stemming from ample supplies of the grains. Soybeans advanced for a third straight session.
The market's focus turned to Thursday's USDA report, which is expected to show higher U.S. corn yields, lower soybean yields and still-ample global supplies of grains and oilseeds.
Intermarket spreading weighed on hard and soft red winter wheat contracts for most of the day as traders sold the lower-protein varieties and bought higher-protein Minneapolis spring wheat futures.
"We've got plenty of wheat, but we don't have plenty of the right kind. The wheat market is developing a very short protein problem," said Roy Huckabay, analyst with Linn & Associates.
Chicago Board of Trade December SRW wheat settled 1/2 cent lower at $4.26-3/4 a bushel while K.C. December HRW wheat rose by a penny to $4.27-1/2. Both ended near session highs.
Minneapolis December wheat futures rose to a six-week high of $6.49 a bushel but closed 8-3/4 cents higher at $6.43-1/2.
Weak demand for lower-protein U.S. wheat in export markets hung over winter crop futures.
Egypt's GASC, the world's top state buyer of wheat, said it bought 120,000 tonnes of Russian wheat in a snap tender.
Meanwhile, Turkey's state grain board TMO announced a tender for 230,000 tonnes of European milling wheat.
"We're not competitively priced on the world market so any time we try to rally it gets snuffed out by the realization that we're not moving wheat at the current price levels," said Brian Hoops, president of Midwest Market Solutions, a brokerage and commodity marketing advisory service.
CBOT December corn rose 1/2 cent to $3.48-1/4 a bushel while January soybeans gained 2-1/2 cents to $9.98-1/2 a bushel.
China imported 5.86 million tonnes of soybeans in October, down 28 percent from the previous month and well below market expectations, customs data showed on Wednesday, after some shipments were delayed.
But the country will commit to buy more U.S. soybeans during President Donald Trump's visit to Beijing this week, a U.S. industry official said, underlining the importance of trade in farm goods even as tensions grow between the world's top two economies. (Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; editing by Susan Thomas and Phil Berlowitz)