| This study was conducted to determine the effects of dietary protein and lipid levels on growth performance,body composition, Organizational digestive enzyme activity, serum non-specific immunities and disease resistance of Exopalaemon carinicauda, in order to providing theoretical basis for optimizing the feed formular for Exopalaemon carinicauda, which included three series.Series 1 Effect of dietary protein and lipid level on growth performance,body composition of Exopalaemon carinicauda.A bifactorial model(4×3) was used to investigates the effect of dietary protein and lipid on growth performance,body composition and digestive enzymes activities of Exopalaemon carinicauda.Twelve groups of shrimp with three replicates and 50 shrimp [average weight(0.21±0.08)g] per replicate were fed twelve experimental diets containing four protein levels(35%, 39%,43% and 47%) and three lipid levels(5%, 7% and 9%) for 8 weeks. Results show that: No interaction between dietary protein and lipid existed for growth performance(P>0.05). Weight gain, specific growth rate,feed conversion ratio and survival rate were significantly influenced by both dietary protein(P<0.05) and lipid levels(P<0.05). Weight gain of shrimp fed with P39 protein and F5 lipid was significantly(P<0.05) higher than that of the other groups. Specific growth rate of shrimp fed with P47 protein was significantly lower than that of the other protein groups(P<0.05). Feed conversion rate of P39F5 grpup was significantly lower than that of the other groups. The P39F5, P39F7 and P43F5 group survival rate was significantly higher than that of the other groups(P<0.05).Proximate analysis indicated that whole-body moisture and protein were affected significantly(P<0.05) by dietary protein. Whole-body lipid was affected significantly(P<0.05) by dietary lipid.The F7 lipid group was significantly higher than that of the other lipid group(P<0.05). Whole-body ash was not affected significantly by both dietary protein(P>0.05) and lipid levels(P>0.05).Series 2 Digestive and metabolic responses of Exopalaemon carinicauda diets differing in protein and lipid levelsThe conceptual design of raising was the same as that of the first experiment.Evaluate the effects of dietary fat and protein on Digestive and Hepatic enzymesactivities of E. carinicauda. Results show that: The intestine amylase and trypsin activities were not affected significantly by dietary protein(P>0.05) and lipid levels(P>0.05),the pepsin activity was affected significantly by both dietary protein(P<0.05)and lipid levels(P<0.05). The P39 and P43 protein group perpsin activity was significantly higher than P35 protein group(P<0.05). No interaction between dietary protein and lipid existed for pepsin 、 intestine amylase and trypsin(P>0.05).The hepatopancreas lipase and alkaline phosphatase activities were affected significantly(P<0.05)by dietary lipid. The interaction between dietary protein and lipid only existed for hepatopancreas lipase.(P=0.017)Series 3 Evaluate the effects of dietary fat and protein on serum non-specific immunities and disease resistance of E. carinicauda.The conceptual design of raising was the same as that of the first experiment.Results show that: The serum phenoloxidase(PM), lysozyme(LZM) and superoxide dismutase(SOD) activities were affected significantly(P<0.05) by different dietary protein.The P43 protein group serum phenoloxidase activity was significantly higher than the other protein group(P<0.05). The P39 protein group lysozyme(LZM) and superoxide dismutase(SOD) activities than the other protein group(P<0.05). The serum superoxide dismutase(SOD) and malondialdehyde(MDA)activities were affected significantly(P<0.05) by different dietary lipid.The F5 lipid group serum superoxide dismutase(SOD) activity was higher than the other lipid group.The F7 lipid group serum malondialdehyde(MDA) activity was significantly higher than the other lipid group. No interaction between dietary protein and lipid existed for serum phenoloxidase(PM), lysozyme(LZM) 、malondialdehyde(MDA)and superoxide dismutase(SOD) activities(P>0.05). The challenge trial results showed that dietary protein level had signficant effects on the ability of the shrimp anti-WSSV infection(P<0.05).Within 48 h and 72 h, cumulative mortality rate of P39 and P43 groups ptotein were signifcantly lower than that of the other groups(P<0.05).In conclusion, diet containing 39% protein, 5%-7% lipid was suitable for Exopalaemon carinicauda. Increased dietary protein level appropriately may enhance the serum phenoloxidase(PM), lysozyme(LZM) and superoxide dismutase(SOD) activities and decrease the mortality of shrimp in the early stage after WSSV infection. In addition,increased dietary protein level appropriately may enhance digestive enzyme activities.The low level of fat may enhance the body resistance tooxidation.More dietary lipid level may led to passive effdect to Hepatopancreas metabolism. And an appropriate increaseof dietary lipid could produce protein-sparing effects. |
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