Effect Of VA And VD Different Levels In Dietary, Respectively, On Growth, Feed Utilization, Immunity, Fat Metabolism Enzyme Activities And FAS, HL MRna Expression Of Grouper(epinephelus Coioides) At Two Stages

A series of 10 weeks feeding experiment was conducted to estimate the effects of dietary vitamin A(VA) and vitamin D(VD) levels on feed utilization, immune activities and lipid metabolism enzyme activities and the key enzyme of lipid metabolism m RNA expression in the liver ofgrouper(Epinephelus coioides) fishat two growth stages.(juvenile grouper,the frist stage,initial weight 7.40g±0.03g; middle grouper, the second stage, initial weight 81.50g±0.05g).The experiment was carried out in toughened glass barrels of mariculture system in laboratory of Guangdong Ocean University Donghai Island biological base. During the rearing period, water temperature was 28.5-31.5 ℃, p H 7.5-8.0, salinity was 26-30‰. The results are presented as follows:1. A 10 week experiment was conducted to to estimate the effects of dietary vitamin A(VA) levels on feed utilization, immune activities and lipid metabolism enzyme activities and the key enzyme of lipid metabolism m RNA expression in the liver of grouper(Epinephelus coioides) fish at two growth stages. Six diets were formulated to contain the different VA levels of 0, 1 000, 2 000, 4 000, 8 000 and 20 000IU/kg of dry diet, respectively.White fishmeal, gelatin and casein(vitamin free) were used as the main protein source, fish oil, corn oil and lecithin as the main lipid source.The feeding trial lasted for 10 weeks. The results showed that the weight gain rate(WGR) and specific growth rate(SGR) were showed the similar trend, which increased and then decreased with the increasing of VA level(P<0.05), WGR in the 2 000 IU group at the first experimental phase was the highest, which significantly higher than that in control group and 20 000 IU group(P<0.05);The WGR at second stage showed the highest in 1 000 IU group, which was not difference with 2 000 IU group(P>0.05), but significantly higher than the other groups(P<0.05). The survival of two trials of the experimental fish were not affected by the level of VA(P>0.05).The feed conversion ratio(FCR) were significantly decreased with the increasing of VA(P<0.05). VA in two trials had no significant effect on HSI of fish(P>0.05), but at the second stage of the experiment, the 1 000 IU group FC was the highest(P<0.05). The contents of moisture, crude protein(CP), crude lipid(CL) and crude ash(CA) in fish whole body had no significant effect in two trials(P>0.05). At the second stage of experiment, the level of VA has great effect on the hepatic lipid deposition, which increased and then decreased(P<0.05). VA significantly increased the superoxide dismutase(SOD) activity in serum and liver(P<0.05), but the serum alkaline phosphatase(AKP) activity had no significant difference(P>0.05). At the second stage of experiment, VA significantly reduced the serum malondial-dehyde(MDA) content(P<0.05), and serum glutamic oxaloacetic transaminase(AST) activity significantly increased(P<0.05). Serum cholesterol(CHOL) decreased significantly(P<0.05), The contents of TG, HDL-C, LDL-C increased and then decreased with the increase of VA(P<0.05). The content of TG and LDL-C which were at the second stage of experimen were showed the highest in group 1 000 IU. The VA levels had significant influence on grouper liver FAS, LPL and HL activity(P<0.05). In the first stage, the FAS, LPL activities were the highest in the 2 000 IU group, but the FAS activity in the 2 000 group and 8 000 IU group had no significant difference(P>0.05), and the activity of HL in the two phase of the experiment showed the highest in group 4 000IU(P<0.05); while at the second stage, the activities of FAS and HSL showed the highest in the 8 000 IU group, and the activity of LPL in 4 000 IU group was the highest, and the CPT-1 activity was significantly affected by the level of vitamin A, which decreased gradually, and then stable(P<0.05). Liver VA deposition were significantly increased with dietary VA level increased, and then tended to be stable(P<0.05); lack or excessive of VA significantly inhibited the FAS and HL expression, when add the optimal amount of VA significantly promoted the FAS and HL expression(P<0.05). In a conclusion, the results indicated that VA in the grouper healthy growth plays an important role. Based on the growth performance, FCR and immune activities of criterion in two phase experiment, when VA level was 2 000IU-4 000IU/kg, the grouper growth performance, feed utilization and immunity showed the highest. Used the serum biochemical indexes, enzyme activities, lipid metabolism of liver VA deposition and FAS, HL gene expression levels as the criterion, added amount of VA in 2 000IU-4 000IU/kg significantly improved lipid metabolism, which significantly higher than the control group and 20 000 IU group. Thus, the optimal VA level in dietary can enhance and improve the grouper lipid metabolism, prevent the lesions caused by excessive fat deposition.2. This study was conducted to evaluate the effect of different VD levels on growth performance and feed utilization in Epinephelus coioides. Six diets contenting VD 0, 500,1000, 2000, 4000 and 10 000 IU / kg, respectively, were confected using formulated with white fish meal, gelatinand casein without vitamin as the main protein sources, and fish oil, corn oil and lecithin oil as the main fat sources. A 10-week feeding experiment was conducted to determine dietary VD requirments of Epinephelus coioides. The results showed that no fish have bone deformities, poisoning and other non-normal phenomen on caused by the lack of or excessive VD during the breeding experiment. Growth and feed utilization were significantly increased with an increase dietary VD(P<0.05) and thereafter declined. WGR and best feed utilization of juvenile fish were at 1000IUgroup(P<0.05), but middle fish was better at500-1 000 IU / kg. No significant differences were found in survival contents of CL and CA(P>0.05) and hepatosomatic index(HSI)(P>0.05). No significant differences were found in FC, AKP, SOD activities(P>0.05) among middle grouper. Contents of CP of juvenile grouper had no significant difference(P>0.05), but 1 000 IU group were significantly higher than other group(P<0.05), liver lipid content increased with increased the levels of VD to decreased and thereafter increased, the lowest showed in 4 000 IU group among middle grouper(P <0.05). AKP activity of 4 000 IU group and SOD activity of 1 000 IU group were the highest in juvenile grouper(P<0.05). Liver SOD activity changed significantly with the VD increased while increased first and then decreased(P<0.05).VD showed significantly lower MDA content in serum(P<0.05) and inhibited the activity of ACP(P<0.05).The CHOL content in serum of juvenile grouper had no significant differences(P>0.05), but CHOL content in serum of middle grouper had decreased significantly lower than the control group(P<0.05). The CHOL and TG content in serum along with the VD of feed showed the same trend, the content of HDL-C and LDL-C rised increased gradually and thereafter declined(P<0.05). VD inhibited significantly FAS activity in liver, improved the activities of total lipoidase(LPL and HL sum activities)(P<0.05), but HSL activity increased significantly with the decrease slightly of CPT-1 activity(P< 0.05) among Middle stage of grouper. Liver VD increased as exponential growth with the increase dietary levels of VD, and FAS and HL m RNA expression had the same tendency as enzyme activities.