Dietary Lysine And Arginine Requirement Of Red Swamp Crayfish(Procambarus Clarkii)

This study was conducted to determine the effects of dietary lysine and arginine levels on growth performance, feed utilization, body composition, physiological and biochemical parameters of red swamp crayfish (Procambarus clarkii), aiming to determine the optimal dietary lysine requirement of this species, in order to provide theoretical basis for optimizing the feed formular for Procambarus clarkii, which included three series:Series 1 Dietary lysine requirement of red swamp crayfish (Procambarus clarkii)This experiment was conducted to evaluate the effects of dietary lysine levels on growth performance, feed utilization, body composition, muscle and hepatopancreas amino acids composition of red swamp crayfish (Procambarus clarkii), aiming to determine the optimal dietary lysine requirement of this species. Seven isonitrogenous (28.26% crude protein) and isocaloric (17.15 kJ·g-1 gross energy) diets were formulated with the protein sources originated from casein, gelatin, wheat gluten and crystalline amino acid (AA) mixture. The measured lysine levels of the experimental diets were 0.76%,1.00%,1.22%, 1.47%,1.69%,1.89% and 2.18%, respectively. Each diet was fed to quadrupled groups of 12 crayfish with initial body weight (7.60±0.01) g in floating net cages (60×60×60 cm). Crayfish was fed three times daily for 60 d. The results indicated that weight gains rate (WGR), specific growth rate (SGR) and feed efficiency ratios (FER) all increased significantly with increasing dietary lysine levels(P<0.05), and their maximum values were attained at 1.69%,1.69% and 1.22%, respectively. However, they all decreased with further increasing dietary lysine levels. Survival rate ranged from 89.58% to 97.92%, and showed no significant difference among all the dietary treatments (P>0.05). Whole-body moisture content of crayfish fed 1.22% dietary lysine was significantly lower than that of crayfish fed 0.76% dietary lysine(P<0.05), but showed little difference with that of the other treatments(P>0.05). The highest whole-body protein and lipid content was observed in crayfish fed 1.89% and 1.69% dietary lysine respectively. They were both significantly higher than that of crayfish fed 0.76% lysine (P<0.05), but showed little difference with that of the other treatments (P>0.05). Hepatopancreas protein content of crayfish fed 1.22% dietary lysine was significantly higher than that of crayfish fed 1.89% and 2.18% dietary lysine(P<0.05). No significant difference was all found in whole-body ash content, muscle composition and muscle AA contents among all the treatments(P>0.05). Digestive enzyme activities (protease, lipase, amylase) all decreased with increasing dietary lysine levels from 1.68% to 2.18%, and their minimum values were attained at 2.18% group, but showed no significant difference among all the dietary treatments (.P>0.05).The second-order regression analysis of WGR against dietary lysine levels indicated that the optimal dietary lysine requirement of red swamp crayfish (Procambarus clarkii) was 1.66% of diet (5.87% of diet protein).Series 2 Effect of dietary lysine levels on non-specific immunity, metabolic and antioxidant indices of red swamp crayfish (Procambarus clarkii)The conceptual design of raising was the same as that of the first experiment. The results indicated that free arginine, free lysine, free methionine, free phenylalanine, free aspartic acid, free glutamic acid, free glycine, free proline concentrations in the hemolymph were both significantly effected by dietary lysine content. The concentration of TP, Blue copper protein, and the activities of ACP in serum of crayfish fed 1.69% and 1.89% dietary lysine was significantly higher than that of crayfish fed 0.76% dietary lysine(P<0.05), but showed little difference with that of the other treatments(.P>0.05). The activities of AST and ALT in hepatopancreas was not significantly affected by dietary lysine (P>0.05). AST and ALT was highest at 1.69% group, and lowest at 0.76% group. Series 3 Dietary arginine requirement of red swamp crayfish (Procambarus clarkii)This experiment was conducted to evaluate the effects of dietary arginine levels on growth performance, feed utilization, and physiological and biochemical parameters of red swamp crayfish (Procambarus clarkii), aiming to determine the optimal dietary arginine requirement of this species. Six isonitrogenous (28.00% crude protein) and isocaloric (15.86 kJ·g-1 gross energy) diets were formulated with the protein sources originated from fish meal, wheat gluten and crystalline amino acid (AA) mixture. The measured arginine levels of the experimental diets were 0.72%,1.12%,1.52%,1.92%,2.32%, and 2.72%, respectively. Each diet was fed to quadrupled groups of 10 crayfish with initial body weight (8.83±0.01) g in floating net cages (60x60x60 cm). Crayfish was fed three times daily for 56 d. The results indicated that weight gains rate (WGR), specific growth rate (SGR) and feed efficiency ratios (FER) all increased with increasing dietary lysine levels, and their maximum values were attained at 2.32%,2.32% and 1.52%, respectively, and then show a downward trend. Survival rate ranged from 65.00% to 72.50%, and showed no significant difference among all the dietary treatments (P>0.05). With the increase of dietary arginine level, the concentration of TP, Blue copper protein in serum, and the activities of ACP all increased, and their maximum values were attained at 1.92%, but showed little difference with that of the other treatments(P>0.05). The dietary arginine levels did not affect the biochemical parameter of in hepatopancreas significantly (P>0.05). The second-order regression analysis of WGR against dietary arginine levels indicated that the optimal dietary arginine requirement of red swamp crayfish(Procambarus clarkii) was 2.04% of diet (7.28% of diet protein).In conclusion, the optimal dietary lysine and arginine requirement of red swamp crayfish (Procambarus clarkii) was 5.87% and 7.28% of diet protein respectively. The optimal dietary lysine decrease the whole-body moisture content, improve the whole-body protein and lipid content. The excessive dietary lysine levels suppress digestive enzyme activities. And an appropriate increase of dietary lysine and arginine could improve the non-specific immunity of Procambarus clarkii.