THE UNTRITION OF SILURUS MERIDIONALIS:Ⅲ. PROTEIN-SPARING EFFECT OF DIETARY LIPID

From October to December, 1997, the growth experiment of the southern sheatfish, Silurus meridionalis, was conducted with initial weight 30—44 g. The fish were fed with artificial formulated diets of different ratios of protein(P)to lipid(L), i.e. 43%P/15%L, 47%P/15%L, 51%P/16%L, 50%P/8%L, 54%P/8%L, 58%P/8%L, in the aquariums with recirculated water system. At each of the diets 4 groups of the Southern Sheatfish(10 fish in each group)were fed at ad libitum ration level for 6 weeks at 27.5℃. Significant difference was not found in specific growth rate(SGR)and food conversion efficiency(FCE)between the fish at the higher lipid and lower protein level of diets and those at the lower lipid and higher protein level. But protein efficiency ratio(PER)in the former was significantly higher than in the later. With the dietary lipid content increased from 8% to 15%, the optimum dietary protein level estimated for the fish declined from 54% to 43%. It was suggested that dietary lipid had significant protein-sparing effect on this fish.