| 1.This experiment was conducted to investigate the effects of dietary vitamin C(L-ascobyl-2-monophosphate)on growth performance,serum biochemistry,related enzyme activities,tissue ascorbic acid concentrations and muscle composition in healthy juvenile C.striata.Seven iso-nitrogenous and iso-energetic diets were formulated in gradient level of vitamin C at 10.97,74.03,148.33,213.64,335.33,618.88,910.98 mg/kg diet,which were fed respectively to 3 replicates and each replicate contained 30 fishes with initial weight about(88.34±24.1)g.Results indicated that after 10 weeks of the feeding trial(two weeks of adaptive phase):1)With the increase of dietary vitamin C,the weight gain rate(WGR),special gain rate(SGR)of fish and protein efficiency of feed increased at first and then decreased,which reached a peak at 74.03 mg/kg.The fishes in 74.03 mg/kg V_C group had significantly higher condition factor(CF)than that in the control group(P<0.05),but its feed coefficient(FE)is the minimum among other six groups.The fish body indices were not significantly different among groups(P>0.05).2)With the increase of dietary vitamin C,the content of total protein(TP)in serum of fish increased at first and then kept steady,the activity of lysozyme(LZM)increased first and then declined,and the LZM activity reached the maximum at 335.55 mg/kg,which was significantly higher than that of the control group(P<0.01).But the alkaline phosphatase(AKP)activities and total cholesterol(CHOL)contents were no significance different(P>0.05).3)The superoxide dismutase(SOD)activities in serum,liver and muscle of juvenile C.striata increased at first and then decreased with the increase of the level of dietary vitamin C,and the activities in 335.55 mg/kg group were the highest.At the same time,the content of malondialdehyde(MDA)in serum and liver was the lowest.The activities of catalase(CAT)in the three issues were not significantly affected by the amount of V_C added to the feed(P>0.05).Total antioxidant competence(T-AOC)increased significantly when vitamin C was added from 10.97 mg/kg to 148.33 mg/kg(P<0.05).4)When the levels of dietary vitamin C increased from 10.97 mg/kg to 618.88 mg/kg,the activity of glutamic oxalacetic transaminase(GOT)in serum decreased continuously,and the activity of liver GOT increased continuously.With the increase of dietary vitamin C,the serum glutamic-pyruvic transaminase(GPT)activity increased at first and then kept steady,but there was no significant difference in the activity of GPT in liver.5)The accumulations of vitamin C in the liver and muscle were all saturated at 335.33 mg/kg,and the amount of accumulation no longer changed significantly when the V_C level increased.But the serum V_C content did not appear to reach a plateau at the addition of910.98 mg/kg.The amount of V_C in the liver was much higher than muscle and serum.6)Dietary V_C supplementation had no significant effect on the crude protein,crude fat and crude ash contents of fish muscle(P>0.05).However,collagen content of muscle increased with the increase of V_C supplement.When the dosage was 910.98 mg/kg,the collagen contents could be as high as 6.21 g/kg.Set the SGR,plateau liver vitamin C and serum LZM activity as evaluation indexes,broken-line regression analysis results indicate that the dietary vitamin C requirement of juvenile C.striata(about 88 g)is estimated to be 66.66mg/kg,309.93 mg/kg and 345.11 mg/kg.2.Grouper is an important world marine economic fish.As a low-fat,high-protein edible fish,it is deeply loved so that its supply is not adequate to the demand.In order to improve the muscles quality of the cultured grouper and provide the basic data for the development of compound feed,the nutritional components in muscles of E.moara,E.lanceolatus,E.moara(♀)×E.lanceolatus(♂)(hereinafter Yunlong)were analyzed and evaluated by routine biochemical analysis methods.The results showed that the contents of crude protein in three species of groupers’fresh muscles were 20.60%,19.30%and 20.00%,respectively,and the contents of crude fat were 2.60%,1.60%and4.30%.Sixteen common amino acids were detected in the muscles of three species of grouper.The contents of total amino acid(TAA),essential amino acids(EAA)and delicious amino acids(DAA)in wet weight fish flesh were 16.95%、7.11%、6.31%,respectively,in E.moara,17.46%,7.18%and 6.83%,respectively,in E.lanceolatus,and 18.56%,7.69%,7.16%,respectively,in Yunlong.The composition proportions of the essential amino acids in the muscles of three species of grouper all accord with the FAO/WHO Standard.The ratios of branched chain amino acid to aromatic amino acid(F values)in 3 species of groupers’muscles were 2.22,2.57,and 2.60,respectively.According to the amino acid score(AAS)and chemical score(CS),the first limiting amino acid of the 3 species of grouper was methionine,and the second limiting amino acid was valine.The EAA index in muscle of Yunlong was the highest(84.37)among the three groupers.In addition,3 species of groupers’muscles were all rich in minerals.The content of potassium is the highest in macroelements,and the content of zinc in trace elements is highest.The ratios of K to Na(K/Na)in the muscle of groupers were all high.Studies have shown that the three species of groupers are high quality marine fish with high nutritional value,which have good prospects for exploitation and utilization.3.C.striata is an important world marine economic fish.In this study the contents of nutritional composition in muscle of C.striata were compared and evaluated by routine biochemical analysis methods between male and female.The results showed that the female C.striata contained very significantly lower moisture than the male(P<0.01).But compared with male,crude fat in fresh muscle of female were very significantly higher(P<0.01).There was no significant difference in crude protein and crude ash contents in fresh muscle between female and male(P>0.05).Sixteen common amino acids were detected in the muscles of both male and female.Except for the contents of methionine,lysine and glycine,there were no significant difference in the other 13 kinds of amino acids and TAA,EAA,DAA(P>0.05).According to the AAS and CS,the first limiting amino acid of female and male C.striata was methionine,and the second limiting amino acid was valine.The EAAI of male C.striata was 85.28,a little higher than that of female C.striata(84.84).The composition proportions of the essential amino acids in the muscles of C.striata all accorded with the FAO/WHO Standard.The F values in flesh of male and female C.striata were 2.28 and 2.24respectively.Monounsaturated fatty acid(MUFA)concentration of male C.striata was higher than female’s,the difference was extremely significant(P<0.01),but the contents of Polyunsaturated fatty acid(PUFA)and EPA+DHA were no significant differences between male and female.The ratio of∑n-3PUFA to∑n-6PUFA in flesh of male C.striata was 6.43,higher than that of female(5.51).In addition,the ratio of K to Na in the muscle of male C.striata was also higher than that of female,the female was 8.27and the male was 14.27.In conclusion,the male C.striata have higher edible value than females. |
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