Processing Soybeans With Sodium Hydroxide and Copper Sulfate for Pigs

Three feeding trials involving a total of 120 individually fed pigs and a metabolism trial were conducted to evaluate the influence of moist heating of soybeans on performance. In one trial sodium hydroxide and copper sulfate, singly or in combination, were added to the cooking water. In the other two trials copper was added to the vitamin–mineral premix. Pigs fed cooked soybeans or soybean meal performed similarly and their performance was superior to that of pigs fed raw soybeans. Alkali-treated cooked soybeans resulted in poorer performance as compared with cooked soybeans. Soybeans cooked with copper sulfate in the water produced improved gain:feed and gain:protein ratios as compared with cooked soybeans. Copper additions to the diet did not influence pig performance. Energy and protein utilization of the soybean meal and cooked soybean diets was similar and superior to that of raw soybean diets except apparent protein digestibility.