Effects Of Phospholipids On Growth Performance,Fatty Acid Composition,Antioxidant Capacity And Lipid Metabolism Of Larval And Juvenile Pearl Gentian Grouper(Epinephelus Fuscoguttatus ♀× E.lanceolatus ♂)

Taking the pearl gentian grouper as the research object,undergoing a certain period of feeding and growth experiment,through some determination methods,the effect of phospholipids on the pearl gentian grouper’s growth performance,fatty acid composition,antioxidant capacity and lipid metabolism was studied.The research content and main results of this article are as follows:1.Effects of dietary phospholipids on growth and body composition of larval and juvenile pearl gentian grouper(Epinephelus fuscoguttatus♀ × E.lanceolatus♂)Taking the pearl gentian grouper larval and juveniles with an initial body weight of(0.37±0.01)g and(13.00±0.02)g as the research object,based on the actual feed,by adjusting the ratio of soybean phospholipid and soybean oil,five different phospholipid levels of 1.87%、3.61%、5.53%、7.25%and 9.69%of the larvae test feed with isonitrogen and other lipids and five different phospholipid levels of 1.41%、3.21%、5.25%、7.02%and 9.13%juveniles test feed were made.After 23 days and 61 days of culture and growth experiments,by measuring the growth indicators and body composition of larvae and juveniles,explore the effect of feed phospholipids on the growth and body composition of larvae and juveniles of pearl gentian grouper,and then determine The optimal requirement of phospholipids for larval and juvenile.The experimental results showed that with the increase of the phospholipid content in the feed,the final body weight(FBW)and specific growth rate(SGR)of pearl gentian grouper larvae both increased first and then decreased,and the maximum value was found in the 7.25%group.The FBW of the 7.25%and 9.69%groups was significantly higher than the other three groups(P<0.05),while the SGR of the 7.25%and 9.69%groups was significantly higher than that of the 1.87%and 3.61%groups(P<0.05).In the juvenile experiment,dietary phospholipids had no significant effect on the final body weight(FBW),specific growth rate(SGR)and survival rate(SR)of juvenile pearl gentian grouper(P>0.05).Dietary phospholipids significantly increased the whole fish protein and lipid levels of pearl gentian grouper larvae.Among them,the protein content of 1.41%group was significantly lower than the other groups except 3.21%group(P<0.05),and the lipid content of 9.13%group significantly higher than the other groups except the 7.02%group(P<0.05).In the juvenile experiment,the lipid content of whole fish and liver in 9.69%group was significantly higher than that in 1.87%group(P<0.05),but there was no significant difference in 3.61%,5.53%,and 7.25%groups(P>0.05).In summary,the growth promotion of pearl gentian grouper fed with phospholipids is mainly in the larval stage,and has little effect on the juvenile stage,but it will affect the absorption and transport of its lipid.Through the simulation equation,the optimal phospholipid requirement of pearl gentian grouper larvae is about 9.19%,and that of juveniles is 5.93%。2.Effects of dietary phospholipids on fatty acid of larval and juvenile pearl gentian grouper(Epinephelus fuscoguttatus ♀× E.lanceolatus ♂)After the breeding experiment,the fatty acids of the whole fish,liver and muscle of the experimental fish were measured.Through data processing,analysis and research,the effect of feed phospholipids on the fatty acids of pearl gentian grouper larvae and juveniles was explored.The experimental results showed that as the feed phospholipid increased from 1.87%to 5.53%,the C14:0 fatty acid content of the whole pearl gentian grouper larvae increased significantly,and then decreased significantly(P<0.05).At the same time,with the increase of feed phospholipid content,the content of C16:0 and saturated fatty acid(SFA)measured in whole fish increased significantly(P<0.05),but dietary phospholipid significantly decreased C18:2n-6,C18:3n-3 and n-6 polyunsaturated fatty acid(PUFA)content(P<0.05).Although there was no significant difference in the content of whole fish fatty acid C20:5n-3 between the groups(P>0.05),the content of C22:6n-3 and long-chain PUFA determined by feeding larvae fish with 3.61%and 7.25%phospholipids was significant higher than the 1.87%group(P<0.05).At the same time,the larvae of fed 3.61%phospholipid,it was observed that the content of n-3 PUFA in whole fish was significantly higher than that of other groups(P<0.05).The n-3/n-6 PUFA content of whole fish increased significantly with the increase of phospholipids in the feed(P<0.05).At the same time,the larvae of fed 3.61%phospholipid experimental diet,the content of n-3 PUFA was significantly higher than that of other groups(P<0.05).The n-3/n-6 PUFA in whole fish increased significantly with the increase of dietary phospholipids(P<0.05).Among the fatty acids measured in whole pearl gentian grouper juvenile fish,dietary phospholipids had no significant effect on the content of C18:0 and C20:4n-6(P>0.05),but significantly increased the C14:0、C16:0、SFA、C16:1、C20:1、C22:6n-3、n-3/n-6 PUFA、n-3 LC-PUFA and DHA/EPA content(P<0.05),and C18:1、MUFA、18:2n-6、n-6 PUFA,、C18:3n-3、C20:5n-3 had the opposite changes.At the same time,the ratio of PUFA measured in 1.41%group was significantly lower than that in 5.25%group(P<0.05).The change trend of muscle fatty acid in pearl gentian grouper larvae and juvenile liver is similar to that of whole fish.At the same time,the change trend of fatty acid composition of pearl gentian grouper larvae and juvenile is basically the same as that of experimental feed.In summary,the fatty acid composition of pearl gentian grouper liver,whole fish and muscle highly reflects the fatty acid composition in the feed.The addition of phospholipids in the feed can promote the absorption and utilization of EFA in the feed.3.Effects of dietary phospholipids on antioxidant capacity of larval and juvenile pearl gentian grouper(Epinephelus fuscoguttatus♀× E.lanceolatus ♂)After the breeding experiment,the antioxidant capacity of the experimental fish liver was measured.Through data processing,analysis and research,the effect of feed phospholipids on the antioxidant capacity of pearl gentian grouper larval and juvenile fish livers was explored.The experimental results showed that in the larval pearl gentian grouper,the content of liver MDA decreased significantly from the 1.87%phospholipid group to the 7.25%phospholipid group(P<0.05).At the same time,the content of MDA in the liver in the 9.69%phospholipid group was significantly higher than that in the 7.25%group(P<0.05),but it was not significantly different from the 3.61%and 5.53%groups(P>0.05).Dietary phospholipids significantly increased the activity of CAT(P<0.05).in addition,the CAT activity in the liver of juveniles fed by 7.25%and 9.69%phospholipid groups was significantly higher than that of the other groups(P<0.05).As the content of phospholipids in the diet increased from 1.87%to 7.25%,SOD activity increased significantly(P<0.05).After that,when phospholipids were added to the feed,the SOD activity decreased slightly.However,among larval fed 5.53%dietary phospholipids,the highest T-AOC activity was obtained,which was significantly higher than the 1.87%and 9.69%groups(P<0.05).In the juvenile experiment,the CAT activity in the liver of the juvenile in the 3.21%phospholipid group was significantly higher than that in the other groups(P<0.05),and the SOD activity was significantly higher than in the 7.02%and 9.13%groups(P<0.05).The dietary phospholipid significantly enhanced the activity of T-AOC and MDA,and achieved the maximum value in the 7.02%group,and the MDA value of the 3.21%group was significantly lower than the other groups(P<0.05).In summary,dietary phospholipids can improve the antioxidant capacity of the liver of pearl gentian grouper larval,In juvenile,too much phospholipid will increase the lipid deposits in the liver,and on the contrary reduce its antioxidant capacity.4.Effects of dietary phospholipids on lipid metabolism of larval and juvenile pearl gentian grouper(Epinephelus fuscoguttatus♀× E.lanceolatus ♂)After the breeding experiment,the genes related to the lipid metabolism of the experimental fish were determined.Through data processing,analysis and research,the effect of feed phospholipids on the expression of genes related to the lipid metabolism of pearl gentian grouper larval and juveniles was investigated.The experimental results showed that dietary phospholipids had no significant effect on the expression of lipogenesis-related genes,liver X receptor a(LXRa),fatty acid synthase(FAS)and acetyl-coenzyme A carboxylase(ACC)in pearl gentian grouper larval(P>0.05).At the same time,the gene expression of diacylglycerol O-acyltransferase 2(DGAT2)was significantly higher in the 9.69%phospholipid group than in the 1.87%group(P<0.05).High dietary phospholipids significantly reduced the expression of peroxisome proliferator-activated receptor α(PPARα)(P<0.05),and the expression levels of larval fed with 1.87%and 3.61%phospholipids were significantly higher than those of other groups(P<0.05).There was no significant difference in the expression of carnitine palmitoyltransferase Ⅰ(CPT1)between different treatments(P>0.05).However,the expression of fatty triacylglycerol lipase(ATGL)decreased significantly with the increase of dietary phospholipids(P<0.05),and its expression in larval,5.53%,7.25%and 9.69%phospholipid group was significantly lower than other treatment groups(P<0.05).In the juvenile experiment,dietary phospholipid levels had no significant effect on the gene expression of FAS and DGAT2 in the liver of juvenile(P>0.05).As the dietary phospholipid level increased from 1.41%to 5.25%,the gene expressions of PPARa,LPL,LXRa and CPT1 in the juvenile pearl gentian grouper were significantly increased(P<0.05),and then significantly decreased(P<0.05),the maximum value was obtained in the 5.25%group.Dietary phospholipids significantly reduced the gene expression of ACC,and the 9.13%phospholipid group was significantly lower than the other groups except the 7.02%group(P<0.05).In summary,dietary phospholipids can regulate the lipid synthesis,transport,decomposition and oxidation processes in the fish body by affecting the expression of genes related to lipid metabolism in the pearl gentian grouper,thereby affecting lipid deposition.