The potential of Bacillus subtilis E20-fermented soybean meal (FSBM) as a partial alternative component of fish meal (FM) in fed diets of orange-spotted grouper (Epinephelus coioides) was evaluated in this study. An FM-based diet and seven diets containing 10%, 20% and 30% and 10%, 20%, 30% and 40% of FM replaced by soybean meal (SBM) and FSBM, respectively, were fed to grouper for 84 days to evaluate possible substitution levels of FM by tracking growth performance, digestive enzyme activity and morphological changes in the liver and distal intestine. No significant differences in survival and muscle composition of grouper were found between controls and treatments. Growth performance and feed efficiency of fish fed diets with FM replaced by FSBM up to 30% were not significantly different from controls, whereas significantly decreased growth performance and feed efficiency occurred with diets containing >20% of SBM. Based on the feed efficiency, the maximum substituted levels of FM by SBM and FSBM in grouper diets were 18.36% and 29.32%, respectively. Based on this study, the research group concluded that FSBM has great potential to be used as a protein source in grouper diets in partial replacement of FM.

Shiu, Y.-L., Hsieh, S.-L., Guei, W.-C., Tsai, Y.-T., Chiu, C.-H. and Liu, C.-H. (2015), Using Bacillus subtilis E20-fermented soybean meal as replacement for fish meal in the diet of orange-spotted grouper (Epinephelus coioides, Hamilton). Aquaculture Research, 46: 1403–1416. doi: 10.1111/are.12294

Two 7-week feeding trials were conducted to evaluate the capacity of golden pompano (Trachinotus ovatus) to use soy protein concentrate (SPC) as a dietary fish meal substitute. In trial I, fish were fed a control diet containing 40% fish meal and other four diets had the fish meal replaced by 20, 40, 60 or 80% SPC. In trial II, a 3 × 2 design was used, and 40 and 80% of the fish meal in control diet was replaced by SPC, with or without 5 g/kg taurine supplementation.

In trial I, no significant difference was found in the feed intake between feeding treatments. The weight gain and nitrogen retention efficiency (NRE) decreased, whereas the feed conversion ratio (FCR) and phosphorus retention efficiency (PRE) increased, with decreasing dietary levels of fish meal. No significant differences were found in the weight gain, FCR and NRE between fish fed control diet and the 20% replacement diet. Fish fed the control diet and/or the 20% replacement had higher weight gain than those fed diets containing higher levels of SPC.

In trial II, no significant differences were found in the feed intake, weight gain, FCR, NRE and PRE between fish fed the control diet and those containing taurine. No significant differences were found in the condition factor, hepatosomatic index and body composition between fish fed the various treatments. The present study reveals that taurine supplementation can elevate fish meal replacement level by SPC in the golden pompano diets. Fish meal in the diet can be reduced from 40 to 32% if the fish meal is replaced with SPC (without taurine supplementation), and fish meal can be further reduced to 24%, if the substituted with SPC plus 5 g kg−1 taurine.

Wu, Y., Han, H., Qin, J. and Wang, Y. 2015. Replacement of fishmeal by soy protein concentrate with taurine supplementation in diets for golden pompano (Trachinotus ovatus). Aquaculture Nutrition, 21: 214–222. doi: 10.1111/anu.12161

This study investigated the effect of soy anti nutrients, saponins and phytosterols, in growing sea bass. Seven diets were formulated: a control diet (fishmeal and fish oil based) and six diets containing 1 or 2 g/kg soya saponins, 5 or 10 g/ kg phytosterols, or a combination of 1 g/ kg saponins plus 5 g/ kg phytosterols or 2 g/kg saponins plus 10 g/ kg phytosterols. After a 59 day feeding trial the fish were weighed, feces collected for digestibility studies and plasma sampled for cholesterol quantification. At day 15 and 59, distal intestine (DI) samples were collected for histological evaluation and quantification of maltase (Malt), alkaline phosphatase (AlP), leucine aminopeptidase (LAP) activities, and tissue was sampled for gene expression of AlP, Malt and immune related genes.

In this study, the added levels of saponins and phytosterols had no effect on fish performance, digestibility, plasma cholesterol levels and digestive enzymes activities and gene expression. Only mild morphological changes were present in groups fed the highest levels of saponins plus phytosterols. Expression of immune related genes showed no differences between treatments groups. Overall, the researchers concluded that growing sea bass showed high tolerance to dietary saponins and phytosterols in the levels tested.

Couto, A., Kortner, T.M., Penn, M., Bakke, A.M., Krogdahl, A. and Oliva-Teles, A. 2015. Dietary saponins and phytosterols do not affect growth, intestinal morphology and immune response of on-growing European sea bass (Dicentrarchus labrax). Aquaculture Nutrition. doi: 10.1111/anu.12220

In a related study aimed to elucidate the effects of two soy anti nutrients, saponins and phytosterols, on growth, intestinal health and function of European sea bass juveniles was studied. Seven fishmeal-based diets were formulated with varying levels of soy saponins and phytosterols. After 59-days, blood was collected for plasmatic cholesterol quantification and intestinal samples were collected for histology, digestive enzymes activity and gene expression analysis. Feeding low levels of phytosterols resulted in increased distal intestine weight and decreased plasma cholesterol, while feeding high levels of phytosterols caused inflammatory changes in the distal intestine. Feeding high levels of saponins depressed some enzyme activity in distal intestine and the histological inflammatory changes. This study indicated that feeding saponins and phytosterols at levels tested did not compromise growth, however, caused some gastrointestinal disturbance that may affect fish in the long term.

Couto, A., Kortner, T.M., Penn, M., Ostby, G., Bakke, A.M., Krogdahl, A. and Oliva-Teles, A. 2015. Saponins and phytosterols in diets for European sea bass (Dicentrarchus labrax) juveniles: effects on growth, intestinal morphology and physiology. Aquaculture Nutrition, 21: 180–193. doi: 10.1111/anu.12146