Same here. It was more apparent in my quail than my ducks. Quail have a much higher protein need, so an inferior protein is more likely to effect them.
Here is a great article on soy and how it came to America...
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POLITICS OF SOY The soybean industry in America is highly monopolistic, controlled by a small number of huge companies like Cargill Corporation, and Archer, Daniels, Midland Company. Archer, Daniels, Midland, the world's major soy processor, spends heavily on advertising, especially for news programs on major networks. The company spends $4.7 million for advertising on Meet the Press and $4.3 million on Face the Nation during the course of a year. ADM also has holdings in major newspapers. They control the media, so naturally the press presents soy in a favourable light. ADM lobbies heavily in Washington and supports university research programs. ADM president, Dwayne Andreas is fanatic about spreading soy-based foods around the world. There is a lot in it for him, but there is not much in it for us.
GENETICALLY ENGINEERED SOY RESULTS IN INCREASED PESTICIDE USE AND DESTRUCTION OF THE SMALL FARMER Soy is basically a monoculture requiring massive amounts of pesticides and herbicides. It is for this reason that Monsanto has recently developed a genetically-engineered strain of soy that is resistant to the herbicide Roundup. The long-term effects of these genetically engineered seeds on our ecology can only be guessed at, but the industry is gloating that within a couple of decades, 75% of all our foods will come from genetically-engineered seeds, with soy foods at the top of the list. Furthermore, this trend towards GMOs (genetically modified organisms) will continue to edge out the small conscientious farmer and producer. It will continue to centralize and industrialize our food production. The soy industry, with the help of the International Monetary Fund is encouraging the cultivation of soy in Third World countries; in essence, displacing traditional crops and ultimately the traditional foods that have nourished these societies for thousands of years. Profit from soy processing of genetically modified crops bypasses the farmer and small businessman, because it requires expensive investment in industrial equipment.
http://www.consumerhealth.org/articles/display.cfm?ID=20000501001338
