Abstract:Fish meal is a major protein source in aquafeeds especially for carnivous fish species. Increasing demand, unstable supply and high price of fish meal with expansion of aquaculture made it necessary to search for alternative protein source. Fermented silkworm pupae is a compound protein of both silkworm pupae and some plant proteins and was a promising substitute for fish meal. To evaluate fermented silkworm pupae as an alternative for fish meal, a 56-day feeding trial in an in-door seawater recirculating system was conducted to investigate the effects of fishmeal replacement by fermented silkworm pupae (FSP) on growth performance, feed utilization blood physiology and enzymatic activities of juvenile turbot with initial average weight of (19.84±0.04 g). Six isonitrogenous and isocaloric practical diets were formulated to replace fishmeal at 0%, 15%, 30%, 45%, 60%, and 75% levels with FSP. Each diet was randomly fed to quadruplicate groups of fish. With the increasing FSP level, the specific growth rate (SGR) and feed efficiency (FE) decreased and was significantly different at over 30% replacement levels (P<0.05). Whole body protein and lipid content decreased with the increasing FSP substitution level, and was significantly different at 75% and 30% replacement level respectively (P<0.05). However, whole body moisture and ash content increased with the increasing fishmeal replacement level, and significant difference was shown at 75% and 30% replacement level respectively (P<0.05). ADC of dry matter (42.53%−54.36%) was significantly lower than the control at 75% replacement level (P<0.05); while ADC of protein (71.67%−86.89%) decreased significantly only when 45% or 75% fish meal was replaced by FSP (P<0.05). Hepatic SOD activity in all treatments was higher than the control and was significantly different at 45% and 60% replacement levels (P<0.05). Results of the present study indicated that FSP could replace 15% fish meal in the diets of juvenile turbot without compromising growth performance, feed utilization, blood parameters and enzymatic activities.
