| Choline and inositol are two vitamin-like nutrients required for the growth and health of aquatic animals.But up to now,studies on the optimal requirements of choline and inositol for Litopenaeus vannamei are scarce and the results are very different.Therefore,in this study,the purified feed was used to study the physiological effects of choline and inositol on the shrimp,to explore the precise nutritional requirements of choline and inositol for L.vannamei.The experimental results are as follows:1.In this study,six isonitrogenous and isolipidic purified diets(containing about 42.20%crude protein and 7.99% crude lipid)were used to culture L.vannamei(initial weight 1.75±0.09 g)for 8 weeks.Diets were supplemented with 0,2000,4000,6000,8000 and 12000mg/kg choline chloride,respectively.Each treatment was randomly assigned to 4 replicated tanks and 30 shrimp in each tank.After the breeding,the growth,whole-body composition,serum metabolites,activities of hepatopancreatic digestive enzymes and antioxidant enzymes,serum metabolome and hepatopancreatic transcriptome of L.vannamei were analyzed.The results of this study showed that dietary choline did not affect the survival,weight gain,specific growth rate,condition factor and hepatosomatic index of L.vannamei.Shrimp fed 6000 mg/kg dietary choline gained the highest crude protein,which was significantly higher than that of shrimp given 12000 mg/kg dietary choline.The serum total cholesterol of shrimp fed 6000 mg/kg choline was significantly higher than that in shrimp fed 4000 mg/kg choline.Dietary choline significantly decreased the content of malondialdehyde(MDA)and the activities of superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)in the hepatopancreas of shrimp.Compared with shrimp given 6000mg/kg choline,glycerophospholipid metabolism pathway was significantly enriched and bile salt-activated lipase-like relative expression was significantly up-regulated in the 0mg/kg choline group.Compared with shrimp given 6000 mg/kg choline,the relative expression of the trypsin-1-like gene in protein digestion and absorption pathway was significantly down-regulated in shrimp fed 12000 mg/kg choline.Dietary choline can reduce the damage of lipid peroxidation by affecting the lipid metabolism of shrimp,and apolipoprotein D may be a potential biomarker in this physiological process.According to the weight gain and degree of oxidative damage,1080 mg/kg dietary total choline can meet the normal growth requirement of L.vannamei,but 2822 mg/kg dietary total choline can significantly reduce the degree of peroxidation damage.2.In this study,three isonitrogenous and isolipidic purified diets(containing about36.44% crude protein and 7.42% crude lipid)were used to culture L.vannamei(initial weight0.38 ± 0.02 g)for 8 weeks.Diets were supplemented with 2500,5000 and 10000 mg/kg choline chloride,respectively.At low salinity of 3‰,shrimps were fed with diets supplemented with 2500,5000 and 10000 mg/kg choline(L2500,L5000 and L10000),while those in the seawater were fed with diets supplemented with 2500 mg/kg choline chloride(S2500).Each treatment was randomly assigned to 4 replicated tanks and 30 shrimp in each tank.After the breeding,the growth,whole-body composition,serum and hepatopancreatic metabolites and the activities of hepatopancreatic digestive and antioxidant enzymes of L.vannamei were analyzed.In this study,results showed that the pepsin activity of shrimp in L2500 group was significantly higher than that in S2500 group.However,there was no significant difference in other indexes of L.vannamei rearing under different salinities.Under the desalination culture condition,the crude lipid content of shrimp in L10000 group was significantly lower than that in L2500 and L5000 groups,but the activity of SOD in the hepatopancreas was significantly higher than that in L2500 and L5000 groups.The triglyceride content of shrimp hepatopancreas in L2500 group was significantly higher than that in L5000 and L10000 groups.The glucose contents of serum and hepatopancreas in L5000 group were the lowest and significantly lower than those in L2500 group.Based on the growth and combined with the results in the second chapter,2500 mg/kg dietary choline chloride can meet the needs of normal growth of L.vannamei rearing at 3‰ salinity.3.In this study,six isonitrogenous and isolipidic purified diets(containing about 36.67%crude protein and 7.44% crude lipid)were used to culture L.vannamei(initial weight 0.78± 0.039 g)for 8 weeks.Diets were supplemented with 0,500,1000,2000,3000 and 4000mg/kg myo-inositol,respectively.Each treatment was randomly assigned to 3 replicated tanks and 30 shrimp in each tank.After the breeding,the growth,whole-body composition,serum and hepatopancreatic metabolites and activities of hepatopancreatic digestive and antioxidant enzymes of L.vannamei were analyzed.In this study,compared with shrimp fed0 mg/kg myo-inositol,the weight gain and condition factor of prawns given other diets were significantly increased.Besides,the hepatosomatic index of prawns increased gradually and reaching the maximum value in the 1000 mg/kg group.The survival was the lowest in shrimp given 0 mg/kg dietary inositol,but there was no significant difference from shrimp given other diets.The total serum protein content of shrimp fed with 2000 mg/kg inositol was significantly lower than that of shrimp fed 0 mg/kg dietary choline.The contents of serum triglyceride,total cholesterol and low-density lipoprotein cholesterol in shrimp fed 0 mg/kg inositol were significantly lower than those in other groups.The content of serum highdensity lipoprotein cholesterol in shrimp fed 0 mg/kg inositol was significantly lower than that in shrimp fed with 4000 mg/kg dietary inositol.Except for the shrimp fed with 2000mg/kg inositol,the total protein content in the hepatopancreas of shrimp fed 0 mg/kg dietary inositol was significantly lower than shrimp given other diets.Meanwhile,the glucose content was significantly lower than that of shrimp fed with 2000 and 3000 mg/kg dietary inositol.When the diet inositol supplementation was ≥1000 mg/kg,the triglyceride content in the hepatopancreas of shrimp was significantly higher than that of shrimp fed 0 mg/kg inositol.There was no significant difference in MDA content in the hepatopancreas of L.vannamei.Compared with other supplemental groups,α-amylase and lipase activities in the hepatopancreas of shrimp fed 0 mg/kg dietary inositol were the highest,but pepsin activity was significantly lower than that in shrimp fed 1000 mg/kg dietary inositol.Compared with other diets,the α-amylase and lipase activities in the hepatopancreas of shrimp fed 0 mg/kg dietary inositol were the highest,but the pepsin activity was significantly lower than that in shrimp fed 1000 mg/kg dietary inositol.Based on the weight gain and the degree of oxidative damage,it is considered that 528 mg/kg dietary inositol could meet the needs of the healthy growth of L.vannamei. |
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