GATT OFFICIAL MEETS WITH U.S. FARM LEADERS The official in charge of agricultural matters in the new round of global trade talks is in Washington today and tomorrow to meet with congressional and Reagan administration officials. Aart de Zeeuw, chairman of the General Agreement on Tariffs and Trade's negotiating group on agriculture, met this morning with members of the House Agriculture Committee. Committee sources said De Zeeuw expressed concern over protectionism and high farm price supports. House lawmakers noted that in 1985 the United States took steps to reduce loan rates, committee staff said. "Members told him (De Zeeuw) that we lowered our (U.S.) loan rates and can't eliminate subsidies unilaterally," one source said. De Zeeuw was told of the U.S. lawmakers' frustration with Japan's restrictive rice import policy, and members defended the U.S. dairy policy, which aims to cut surplus production by subsidizing producers to trim herds, sources said. Later today De Zeeuw will meet the Senate Agriculture members and Undersecretary of State Affairs Allen Wallis. Tomorrow, De Zeeuw is to meet the House Ways and Means Trade Subcommittee and the Senate Finance Committee, before visiting Agriculture Secretary Richard Lyng. De Zeeuw goes to Canada later this week. His trip to North America is part of his attempt to meet farm policy leaders in the key GATT member states. The negotiating group on agriculture held its first meeting in February and is expected to meet again in May.