Nutritive value of whole soybeans fermented with Aspergillus oryzae or Rhizopus oligosporus as evaluated by neonatal pigs

Abstract

Two experiments were conducted to evaluate the nutritive effects of heated whole soybeans fermented with the mold Aspergillus oryzae (AOS) or Rhizopus oligosporus (ROS) in diets fed to neonatal pigs from 1 to 22 d of age. In experiment 1, either soybean meal or heated whole soybeans fermented with ROS replaced 75% of the dried skim milk protein. The average daily gain (ADG) and gain-feed (G-F) ratio of pigs fed the diet containing 100% milk protein were greater than those of pigs fed the diets containing either soybean meal or ROS. In experiment 2, heated nonfermented whole soybeans (HUS) or heated whole soybeans fermented with either AOS or ROS replaced 50% of the milk protein in isonitrogenous and isoenergetic diets. Proximate and amino acid analyses of HUS and the fermented soybean products, AOS and ROS were similar. Pigs fed a diet containing either HUS or AOS had greater (P less than 0.05) mean ADG and G-F ratios than pigs fed the diet containing ROS. Apparent biological value, apparent net protein utilization and digestible and metabolizable energy utilization were similar for all dietary treatments. In conclusion, the protein and energy values of whole soybeans were not improved by fermentation with ROS or AOS compared to nonfermented heated whole soybeans, soybean meal or dried skim milk in diets fed to neonatal pigs.