The feeding experiment was conducted to determine the response of juvenile abalone, Haliotis discus hannai, to dietary calcium, phosphorus and the ratios of calcium to phosphorus. Fifteen isonitrogenous(approximately 30% CP)casein-gelatin-based diets containing five graded levels of phosphorus(0%, 0.5%, 1.0%, 1.5% and 2.0%.for each of three levels of calcium (0%, 1.0% and 2.0%)were fed to the animals previously fed a basal diet(0.23% total P and 0.17% total Ca) for 14 days. After 16 weeks of feeding, survival ranged from 94.7% to 100.0% with no significant difference among dietary treatments. The weight gain rate(WGR), daily increment in shell length (DISL), carcass concentrations of lipid and protein, soft-body alkaline phosphatase activity and phosphorus, zinc, manganese contents were significantly affected by dietary phosphorus levels. Supplementation of 1.0% and 2.0% calcium to the basal diet reduced soft-body phosphorus deposition and did not appear to increase the nutritive value of the diet, indicating that a dietary calcium supplement is not required under the present experimental conditions. The dietary phosphorus requirements were evaluated from the pooled WGR and DISL, respectively, by using the second-order polynomial regression analysis. On the basis of the pooled WGR and DISL, the optimum ranges of dietary available phosphorus were 0.65-1.17% (approximately 0.7-1.2% total P), and 0.64-1.14%(approximately 0.7-1.2% total P), respectively. Based on these results, about 1.15% available phosphorus(1.25% of total P.is recommended for the maximum growth of H) discus hannai, and if dietary available phosphorus is reduced from 1.15% to 0.65%, the growth of the abalone may be depressed with 5% likelihood. The calciumrphosphorus ratio of the diets is not important within the range assessed(approximately 0.1:1-9.0:1). q2001 Elsevier Science B.V. All rights reserved.

A growth experiment was conducted to determine the optimal dietary protein to energy (P/E) ratio for juvenile Japanese seabass (initial average weight 6.26F0.10g). Nine practical diets were formulated to contain three protein levels (36%, 41% and 46%), each with three lipid levels (8%, 12% and 16%), in order to produce a range of P/E ratios (from 19.8 to 28.6mg protein kJ 1). Each diet was randomly assigned to triplicate groups of 60 fish in sea floating cages (1.5 1.5 2.0m). Fish were fed twice daily (06:30 and 16:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 26.5 to 32.5 jC, the salinity from 32xto 36xand dissolved oxygen content was approximately 7mg l 1 during the experimental period. The results showed that the growth was significantly affected by dietary P/E ratio (P<0.05). Fish fed the diets with 46% protein (12% and 16% lipid, P/E ratio of 26.7 and 25.7mg protein kJ 1) had the highest specific growth rates (SGR) (4.26 and 4.24% day 1). However, fish fed the diet with 41% protein and 12% lipid showed comparable growth (4.20% day 1), and had higher protein efficiency ratio (PER), protein productive value (PPV) and energy retention than other groups (P<0.05). No significant differences in survival were found among dietary treatments. Carcass lipid content positively correlated with dietary lipid level irrespective of protein level and inversely correlated with carcass moisture content. Carcass protein and ash contents increased with increasing dietary lipid at each protein level. These results suggest that the diet containing 41% protein and 12% lipid with P/E of 25.9mg protein kJ 1 is optimal for Japanese seabass.

The experiments were conducted to investigate the effects of dietary myo-inositol on the survival, growth, proximate composition and de novo synthesis of myo-inositol in abalone, Haliotis discus hannai Ino. The possible inositol-synthesizing capacity of intestinal microflora was also examined. Seven semipurified diets were formulated to provide graded levels of myo-inositol (28.7-1020.1mg/kg diet). A control diet, the basal diet supplemented with 4g/kg tetracycline hydrochloride, was employed to suppress synthesis of myo-inositol by intestinal bacteria. Abalone juveniles of similar size (weight, 144.6 6 0.8mg; shell length, 10.92 6 0.10mm) were distributed in a flow-through system using a completely randomized design with eight treatments and three replicates per treatment. They were fed the appropriate diets once daily for 16wk. Survival, growth, crude protein, lipid, moisture of whole soft body and visceral inositol content were independent of myo-inositol supplementation (P. 0.05). The addition of the antibiotic also did not affect the survival, growth and whole soft body composition. It indicated that intestinal microflora contributed little to the myo-inositol nutrition in abalone. The present study, for the first time, demonstrated de novo synthesis of myo-inositol in mollusks because the visceral tissue of abalone showed high levels of myo-inositol synthetase activities (combined activities of myo-inositol-1-phosphate synthetase and inositol-1-phosphatase), ranging from 74.0 to 98.2mmol/(hzg protein). The enzyme activity significantly and negatively correlated with dietary myo-inositol level (r520.81). Hence, dietary myo-inositol is not essential for abalone because tissue synthesis of the vitamin appears to be sufficient to support normal growth and health of this mollusk.