The agricultural industries in the U.S., Canada and Mexico on Wednesday jointly urged the negotiators for the North American Free Trade Agreement to make as few changes as possible to the trade deal, warning that any change could severely disrupt the economies of all three nations. In a public letter, the American Farm Bureau Federation, the Canadian Federation of Agriculture, and Mexico's National Agricultural Council said their industries are integrated as a result of the 1993 trade deal, which has greatly improved efficiency. The letter was addressed to U.S. Trade Representative Robert Lighthizer and his counterparts in Mexico, Secretary of the Economy Ildefonso Villarreal, and in Canada, Minister of Foreign Affairs Chrystia Freeland. The three began the first round of talks to renegotiate NAFTA on Wednesday.