Grain and soybean futures prices edged lower in early trading today on the Chicago Board of Trade amid fears that Moscow's reprisals against Lithuania could jeopardize U.S. grain sales to the Soviet Union. Reports that the Soviet Union had cut off oil shipments to the breakaway republic triggered speculation that the United States will back away from granting the Soviets most favored nation trade status. The designation would allow for freer trade between the superpowers. Forecasts for increasingly wet, warm weather in the Midwestern croplands prompted further selling this morning. Rain was expected in the region today and Friday, and the National Weather Service has predicted above-normal temperatures for the Midwest during the latter half of next week. Higher prices for soybean meal in Europe helped to limit losses in the soybean market. In early trading, wheat futures were } cent to 1{ cents lower with the contract for delivery in May at $3.63} a bushel; corn was { cent to 1 cent lower with May at $2.72} a bushel; oats were { cent to 1 cent lower with May at $1.56{ a bushel; soybeans were { cent lower to \ cent higher with May at $5.94\ a bushel. Cattle futures were mixed in early trading on the Chicago Mercantile Exchange while pork futures advanced, led by a surge in pork-belly prices amid bullish chart signals. Live cattle futures were .05 cent lower to .20 cent higher with April at 79.82 cents a pound; feeder cattle were .10 cent lower to .05 cent higher with April at 84 cents a pound; live hogs were unchanged to .35 cent higher with April at 56.90 cents a pound; frozen pork bellies were .68 cent to 1.58 cent higher with May at 60.90 cents a pound. Cattle futures were mixed on Wednesday while pork futures were mostly higher.