Bioprocessed soybean meal replacement of fish meal in rainbow trout (Oncorhynchus mykiss) diets

This 125-day experiment evaluated the growth of adult rainbow trout (Oncorhynchus mykiss) fed one of three isonitrogenous and isocaloric diets (46% protein, 16% lipid). Fish meal was the primary protein source for the reference diet, which was compared to two other diets where bioprocessed soybean meal replaced 60% or 80% of the dietary fish meal. At the end of the experiment, there were no significant differences in gain, percent gain, feed conversion ratio, or specific growth rate among the dietary treatments. There were also no significant differences in intestinal morphology, splenosomatic index, hepatosomatic index, and viscerosomatic index among the diets. Based on these results, bioprocessed soybean meal can replace at least 80% of the fish meal in adult rainbow trout diets.