Effects of soybean processing methods on the growth of carp ( Cyprinus carpio)

Abstract

Soybean meals, oil-extracted but not toasted, were heated for different lengths of time at 17% moisture and at 105° C. The degree of heating of these meals, of “Haypro” and of full-fat extruded soybeans was evaluated using several chemical procedures. Commercial soybean meal in rations for carp was replaced by these experimental products on the basis of equal protein and fat contents. Synthetic methionine was included in all experimental rations. Growth rates of carp were reduced by insufficiently heated meals. Growth rates were equal for properly heated and slightly overheated meals. Properly heated or slightly overheated meals were improved very significantly by the addition of lysine, but not by arginine. “Haypro” or full-fat soybeans did not show any advantage over commercial soybean meal with its oil content reconstituted to the level of undefatted meal. It was concluded that the limiting factor for the growth of carp in properly processed commercial soybean meals was not the residual antitrypsin, but inadequate lysine.