PURPOSE: To obtain the subject composition useful as a feed additive effective in increasing the feeding rate of feed and improving the growth of animal by extracting defatted soybean with water and heating the obtained extraction liquid containing oligosaccharide to inactivate trypsin inhibitor, etc.

CONSTITUTION: Water is added to defatted soybean to extract oligosaccharide. The extraction liquid is heated at 60-130°C (preferably 100-120°C) usually for 5-300sec and the objective composition is prepared from the treated extraction liquid. Concretely, the objective composition is produced preferably by suspending 1 pt.wt. of defatted soybean in 7-12 pts.wt. of water, extracting at 40-50°C for 20-40min, heating the extraction liquid under the above condition and spray-drying the treated liquid with a spray drier, etc.