Comprehensive Evaluation Of Fermented Silkworm Pupae As An Innovative Protein Source For Turbot (Scophthalmus Maxius L.)

For the prupose of providing basic data and theoretical foundation for theexploring of new protein souce for aquaculture, a series of experiments were designedto test the potential of fermented silkworm pupae as an innovative protein source forjuvenile turbot（Scophthalmus maxius L.）（19.84g or8.21g）. The experiments arepresented as follows:1. A56-day feeding trail in an in-door seawater recirculating system was conducted toinvestigate the effects of fishmeal replacement by fermented silkworm pupae (FSP)on growth performance, feed utilization blood physiology and enzymatic activities ofjunvile turbot (initial average weight19.84±0.04g). Six isonitrogenous (50.33±0.05%CP kg-1) and isocaloric (17.28±0.06MJ kg-1) practical diets wereformulated to replace fishmeal at0%,15%,30%,45%,60%,75%level with FSP. Eachdiet was randomly fed to quadruplicate groups of fish. The results showed that withincreasing FSP levels, the specific growth rate (SGR) and feed efficiency (FE)decreased and was significantly different at over30%replacement level (P<0.05).Whole body protein and lipid content decreased with increasing FSP substitutuin level,and was significantly different at75%and30%replacement level respectively(P<0.05). However, whole body moisture and ash content increased with increasingfishmeal replacement level, and significant difference was shown at75%and30%replacement level respectively (P<0.05). ADC of dry matter (42.53-54.36%) wassignificantly lower than Control at75%replacement level(P<0.05); while ADC ofprotein (71.67-86.89%) decreased significantly only when45%or75%fish meal wasreplaced by FSP (P<0.05). Hepatic SOD activity in all treatments was higher than the control and was significantly different at45%and60%replacement level (P<0.05).Results of the present study indicated that FSP could replace15%fish meal in thediets of juvenile turbot without compromising growth performance, feed utilizaiton,blood parameters and enzymatic activities.2. To further exploit the potential of applying fermented silkworm pupae as thenew protein source for tubot, basic nutrition composition and amino acid compositonof water-washing, alcohol-washing and untreated silkworm pupae were tested andcompared with Peru red fish meal. Five index, i.e. AAS, CS, EAAI, RC, SRC, wereemployed to analysis the balance of amino acid with a reference to the whole bodyamino acid composition of turbot. The results showed: crude protein was over54%inall types of fermented silkworm pupae; crude lipid varied among treatments; crudeash content was lower than fish meal. The absolute contents of all amino acids werehiger after treatment except for proline. AAS and CS showed similar results: fishmeal>water-washing> alcohol-washing> untreated. The first limiting amino acid wassulfur-containing amino acid, with lysine, arginine, theronine as other limiting aminoacid. EAAI was relatively high in silkworm pupae, ranging from97.01to97.96,whereas was slightly below fish meal (99.72). Similarly, SRC ranges between77.26and79.18, and was inferior to fish meal (83.10). In conclusion, fermented silkwormpupae is a promising substitution for fish meal with high protein, high energy, andwell-balanced amino acid composition in the feed of turbot.3. A62-day feeding trail in an in-door seawater recirculating system wasconducted to investigate the effects of dietary fermented silkworm pupae (FSP) levelson growth performance, feed utilization blood physiology and enzymatic activities ofjunvile turbot (intial average weight8.21±0.02g). Ten isonitrogenous (49.32±0.25%CP kg-1) and isocaloric (20.60±0.20MJ kg-1) practical diets wereformulated to replace fish meal at0%,15%,30%and45%with water-washing,alcohol-washing and untreated silkworm pupae respectively. Each diet was randomlyfed to quadruplicate groups of fish, and each stocked with30fish. Fish were fed twicedaily (8:00and18:00) to apparent satiation. The results showed that with increasingFSP levels, the specific growth rate (SGR), feed efficiency (FE), whole body lipid content of decreased but the daily feed intake (DFI) and whole body protein, moistureand ash content increased significantly (P<0.05). No significant differences wereobserved in serum glucose level among treatments (P>0.05) while proteinconcerntration decreased significantly with dietary FSP level (P<0.05). Serumtriglyceride concentration was depressed significantly with inclusion of FSP exceptfor alcohol-washing group (P<0.05). The activities of protase and amylase, paralledwith apparent digestibility coefficient (ADC) of dry matter and protein, first increasedand then decreased with increasing fish meal substitution (P<0.05). There was nosignificant difference of activities of alanine (ALT) and aspartate aminotransferases(AST) among treatments (P>0.05). Activity of superoxide dismutase (SOD) in theliver was signifcantly higher in fish fed diets containing45%FSP protein comparedwith the control except for alocohol-washing FSP (P<0.05). Results of the presentstudy indicate that FSP could replace15%fish meal in the diets of juvenile turbotwithout compromising growth performance, feed utilizaiton and health of the fish.Futhermore, the processing method of alcohol-washing could enhance lipidavailablity of diets but lose some effect on immunity.