THE NUTRITION OF SILURUS MERIDIONALIS: EFFECTS OF DIFFERENT LEVELS OF DIETARY SOYBEAN PROTEIN ON DIGESTIBILITY AND FEEDING RATE

A growth experiment was conducted on Silurus meridionalis, with initial weight of 23 .78 ±0.09g, for 6 weeks at 27.5±0.02℃ in recirculating system. Using chromic oxide as an indicator, six isonitrogenous(48% protein)and isoenergetic(gross energy, 20KJ/g)diets, with soybean protein(SP)replacing 0%, 13%, 26%, 39%, 52% and 65% of fish meal protein(FP), were formulated to examine the effects of incorporation of dietary SP on digestibility and feeding rate. The results indicated that dietary level of SP significantly influenced feeding rate and apparent digestibility in this souther sheatfish(P 0.05). With the increased SP, the apparent digestibility of dry matter, protein, lipid and energy decreased. When SP in the diet was 65%, the apparent digestibility was significantly lower than that in other groups(P 0.05). Feeding rate increased with the increased SP. Fish fed the diets with 52% and 65% of SP showed significantly higher feeding rate than other groups(P 0.05). It is suggested that the digestibility was an important factor affecting the utilization of soybean meal for the southern sheatfish, but the feeding rate didn't.