Feeding fermented soybean meal diet supplemented with taurine to yellowtail Seriola quinqueradiata affects growth performance and lipid digestion

Feeding experiment was conducted to determine whether fermentation and taurine supplementation of soybean meal (SBM) fed to yellowtail improve growth performance and lipid digestion. Six diets were formulated and designated as SBM, SBM supplemented with taurine (SBM+T), SBM fermented by Bacillus spp. (FSBM1), SBM fermented by Lactobacillus spp. (FSBM2), FSBM2 supplemented with taurine (FSBM2+T), and fish meal (FM). Yellowtail fingerlings with an initial body weight of 42g were stocked in 200-L tanks. The fish were fed, each diet was fed twice daily in two separate tanks for 8weeks. Results showed that lipid digestibility of the SBM diet was significantly lower than that of the FM diet, but SBM diet lipid digestibility was improved by taurine supplementation and fermentation. Lipase activity in anterior intestinal digesta, lipid contents in liver and muscle, and bile acid concentrations in gallbladder and anterior intestinal digesta were significantly lower in fish fed SBM diet than in fish fed FM diet; these parameters were not significantly different between fish fed SBM+T, FSBM2, FSBM2+T diets and FM diet. Although taurine supplementation or fermentation improved lipid digestibility compared with FM diet, growth parameters were only improved in the fish fed FSBM2+T diet, indicating that apart from a lack of taurine, SBM contains other factors responsible for inferior growth of yellowtail. These factors can be partially eliminated by Lactobacillus spp. fermentation.