Requirement Of Several Water-soluble Vitamins And Nutritional Physiology Of Carbohydrate In Large Yellow Croaker (Pseudosciaena Crocea) And Japanese Seabass (Lateolabrax Japonicus)

Feeding trials were conducted in indoor flow-through system (120L,200L or 300 L/tank) or in seawater floating net cages (1.0 m×1.0m×1.5mor 1.5m×1.5 m×2.0 m) to investigate the effects of inositol, choline, niacin and carbohydrate on nutritional physiology of large yellow croaker(Pseudosciaena crocea) and Japanese seabass (Lateolabrax japonicus). Results of these studies are presented as follows:1. Dietary niacin did not signicantly influence survival of large yellow croaker (P>0.05). The weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) were the lowest in fish fed the basal diet, and increased with increasing dietary niacin up to 18.21 mg/kg (P<0.05), and leveled off (P>0.05). No significant difference was observed in whole-body composition and hepatosomatic index of large yellow croaker among all the groups (P>0.05). The hepatic niacin concentration significantly increased when the dietary niacin is 1.09-12.34 mg/kg (P<0.05), and leveled off when the dietary niacin content increased to 18.21 mg/kg (P>0.05). On the basis of SGR and hepatic niacin concentrations, the optimum dietary niacin requirements of juvenile large yellow croaker were estimated using broken-line regression analysis to be 17.41 and 21.97 mg/kg, respectively.2. Survival of large yellow croaker was the lowest in fish fed the basal diet, which was significantly lower than fish fed diets supplemented with 18.21mg/kg niacin or higher (P<0.05), but no significant differences in survival were observed among the niacin-supplemented dietary groups (P>0.05). The weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) were the lowest in fish fed the basal diet, and increased with increasing dietary niacin up to 18.21 mg/kg (P<0.05), and leveled off (P>0.05). No significant difference was observed in whole-body composition and hepatosomatic index of Japanese seabass among all the groups (P>0.05). The hepatic niacin concentration significantly increased when the dietary niacin is 1.09-12.34 mg/kg (P<0.05), and leveled off when the dietary niacin content was more than 18.21 mg/kg (P>0.05). On the basis of SGR and hepatic niacin concentrations, the optimum dietary niacin requirements of juvenile Japanese seabass were estimated using broken-line regression analysis to be 19.45 and 22.17 mg/kg, respectively.3. Dietary inositol significantly enhanced the survival of large yellow croaker (P<0.05). The weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) were significantly improved with dietary inositol increasing from 48.45 to 216.07 mg/kg (P>0.05), and leveled off with further increasing dietary inositol level (P<0.05). No significant differences were observed in moisture, crude protein, ash and hepatosomatic index of large yellow croaker among all the groups (P>0.05), however, crude lipid of this fish significantly increased with increasing dietary inositol level (P<0.05). Hepatic lipid concentrations of fish fed the basal diet with or without succinylsulfathiazole were significantly higher than fish fed with inositol-supplemented diets (P<0.05), and no significant differences were observed among the inositol-supplemented treatments. Inositol concentrations in livers significantly improved with increasing dietary inositol up to 216.07 mg/kg (P<0.05) and then leveled off (P>0.05). No significant differences were observed between growth performance and physiology indices of fish fed the basal diet with or without succinylsulfathiazole which demonstrated that de novo synthesis of inositol was not performed or insufficient for normal growth of large yellow croaker under these experimental conditions. On the basis of SGR and hepatic inositol concentrations, the optimum dietary inositol requirements of juvenile large yellow croaker were estimated using broken-line regression analysis to be 313.35 and 335.29 mg/kg, respectively.4. Survival of Japanese seabass was not significantly influenced with increasing dietary inositol level (P<0.05). However, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) significantly improved with increasing dietary inositol level (P<0.05). SGR and FE leveled off when dietary inositol was more than 216.07 mg/kg while WG leveled off with dietary inositol more than 396.76 mg/kg (P>0.05). No significant differences were observed between the values of fish fed the basal diet with or without succinylsulfathiazole which demonstrated that de novo synthesis of inositol in gut was not performed or insufficient for normal growth of Japanese seabass. Hepatosomatic index and hepatic lipid concentrations of fish fed the basal diet with or without succinylsulfathiazole were highest, and significantly higher than fish fed with diets containing 216.07 mg/kg inositol or more (P<0.05), and no significant differences were observed among the inositol-supplemented treatments. Inositol concentrations in livers were lowest in fish fed the inositol-unsupplemented diets, which were lower than fish fed diets containing 396.76mg/kg inositol or more, and no significant differences were observed among the inositol-supplemented treatments (P>0.05). On the basis of SGR and hepatic inositol concentrations, the optimum dietary inositol requirements of juvenile Japanese seabass were estimated using broken-line regression analysis to be 261.22 and 317.20 mg/kg, respectively.5. Survival of large yellow croaker was significantly lower in fish fed the basal diet than those of fish fed diets supplemented with 682.99 mg/kg choline or higher, but no significant differences in survival were observed among the choline-supplemented dietary groups (P>0.05). The weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) significantly improved with increasing dietary choline level. SGR leveled off when dietary choline is 372.12 mg/kg or higher while WG and FE leveled off with dietary inositol more than 682.99 mg/kg (P<0.05). With increasing dietary choline level, hepatic lipid concentrations and hepatosomatic index of large yellow croaker significantly decreased while serum triglyceride and cholesterol significantly increased (P<0.05). Choline concentrations in livers significantly improved with increasing dietary inositol up to 682.99 mg/kg (P<0.05), and then leveled off (P>0.05). On the basis of SGR and hepatic inositol concentrations, the optimum dietary choline requirements of juvenile large yellow croaker were estimated using broken-line regression analysis to be 1056.64 and 1124.28 mg/kg mg/kg, respectively.6. No significant differences were observed in survival of large yellow croaker among various dietary treatments (P>0.05). The weight gain (WG) and specific growth rate (SGR) significantly improved with increasing dietary choline up to 1253.96 mg/kg (P<0.05), and then leveled off (P>0.05). Feed efficiency (FE) was significantly lower in fish fed with basal diet than that fed with choline-supplemented diets (P<0.05). With increasing dietary choline level, hepatic lipid concentrations and hepatosomatic index of Japanese sebass significantly decreased while serum triglyceride and cholesterol significantly increased (P<0.05). Choline concentrations in livers significantly improved with increasing dietary inositol up to 682.99 mg/kg (P<0.05), and then leveled off (P>0.05). On the basis of SGR and hepatic inositol concentrations, the optimum dietary choline requirements of juvenile Japanese sebass were estimated using broken-line regression analysis to be 929.40 and 1013.35 mg/kg, respectively.7. No significant differences were observed in survival of large yellow craoker among dietary treatments with graded levels of carbohydrate (P>0.05). However, with the increasing of dietary carbohydrate levels, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) increased when dietary CBH content is between 1.86 and 19.40%, and then decreased with dietary CBH further increased (P<0.05). Dietary CBH did not influence content of crude protein, moisture and ash of large yellow croaker, but significantly improved crude lipid, liver glycogen, muscle glycogen and serum glucose (P<0.05). No significant differences were observed in protease among dietary treatments. However, the amylase activities in the intestine significantly increased with increasing dietary CBH levels (P<0.05). Digestibility coefficients (ADCs) of dietary protein, lipid and CBH significantly decreased with increasing dietary CBH levels (P<0.05). ADCs of lipid were significantly lower when dietary CBH level is 13.56% or higher compared to basal diet. However, there was no significant effect on the apparent digestibility coefficients (ADC) of protein and CBH when dietary CBH level was no more than 19.40%. On the basis of SGR, the optimum dietary carbohydrate level for the growth of large yellow croaker was estimated using second-order polynomial regression analysis to be 22%.8. No significant differences were observed in survival of Japanese seabass among dietary treatments (P>0.05). However, with the increasing of dietary carbohydrate levels, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) increased when dietary CBH content is between 1.86 and 19.40%, and then decreased with dietary CBH further increased (P<0.05). Dietary CBH significantly improved the content of crude protein and crude lipid, but significantly decreased moisture and ash of Japanese seabass (P<0.05). With increasing dietary CBH, liver glycogen and serum glucose concentration significantly increased (P<0.05), and then leveled off. However, no significant differences were observed in muscle glycogen concentration among dietary treatments. Amylase and protease activities in livers significantly increased with increasing dietary CBH levels (P<0.05), while hexokinase activity was not influenced with dietary CBH levels. Digestibility coefficients (ADCs) of dietary nutrients significantly decreased with increasing dietary CBH levels (P<0.05). However, there was no significant effect on the apparent ADCs of nutrients when dietary CBH level was no more than 19.40%. On the basis of SGR, the optimum dietary carbohydrate level for the growth of Japanese seabass was estimated using second-order polynomial regression analysis to be 19.8%.