Study On Fatty Acid Requirement And Suitable Lipid Source Of Russian Sturgeon Acipenser Gueldenstaedti

Russian sturgeon(Acipenser gueldenstaedti)is one of the oldest fish species along the course of fish evolution and is reputed for its long evolution history,large body size,delicious flesh and nutritional eggs.The life cycle of this species was closed in 1969 and most studies have focused on its systematics and general biology in the last half century,but the rearing trial of sturgeons for meat production on farm is in infancy.The effects of different lipid sources and various levels of linoleic and linolenic acids in dietary on growth performance,lipid metabolism and antioxidant status of sturgeon has been investigated.The essential fatty acids of sturgeon and their requirements were also explored.And we also conducted the effects of n-3 HUFA in dietary on sturgeon.Results in our study will not only contribute to fish nutrition physiology,but also can be beneficial to the artificial feeding and diets of sturgeon.1.Effects of dietary lipid sources on growth performance,lipid metabolism and antioxidant status of juvenile Russian sturgeonSix isonitrogenous and isoenergetic diets were used to test the influence of lipid source on growth performance,antioxidant status and lipid metabolism of juvenile Russian sturgeon,Acipenser gueldenstaedti.Each diet was supplemented with 90 g kg-1 of lipid from each of six sources including fish oil(FO),beef tallow(BT),sunflower oil(SO),linseed oil(LO)and equal combinations of FO + SO + BT(FSB)or LO + SO + BT(LSB).After 56-days,fish fed LSB demonstrated highest weight gain,specific growth rate and lowest hepatosomatic index among all groups.The n-6 polyunsaturated fatty acids(PUFAs)in the whole fish were highest in the SO group,and n-3 PUFAs were highest in fish fed LO.The fish fed FO contained highest n-3 highly unsaturated fatty acids.Triglyceride in the serum of fish fed LSB was lowest,but was not significantly different from that in the SO group.Triglyceride in the serum of fish fed FO and BT was highest among all groups.Lipase,malate dehydrogenase and lipoprotein lipase activities were highest in fish fed LSB.Serum malondialdehyde in fish fed LSB was significantly lower than in fish fed FO or SO,but no significant differences were found among fish fed LSB,BT,LO or FSB.Fish fed LSB showed higher catalase activity and total antioxidant capacity than fish fed FO or FSB.This study indicates that linseed,sunflower oil and beef tallow mixed oil are a suitable lipid source and can benefit growth performance and anti-oxidation in juvenile sturgeon.2.Growth performance,lipid requirement and antioxidant capacity of juvenile Russian sturgeon fed various levels of linoleic and linolenic acidsTo evaluate the effects of dietary linoleic(LA)and linolenic acids(LN)on growth,enzyme activities to lipid addition and antioxidant capacity of the Russian sturgeon,Acipenser gueldenstaedti,10 diets with different sources of lipid were formulated.Coconut oil in the basal diet was replaced by sunflower oil to make three diets(LA0.5+LN0,LA1.0+LN0,LA2.0+LN0)with dietary LA at 0.5%,1.0%and 2%,by perilla oil to obtain three diets(LA0+LN0.5,LA0+LN1.0,LA0+LN2.0)with dietary LN at 0.5%,1.0%and 2%,and by the combination of sunflower oil and perilla oil to provide three diets(LA0.25+LN0.25,LAO.5+LN0.5,LA1.0+LN1.0)containing LA and LN at 0.25,0.50 and 1.00%.Coconut oil was used as the control diet at 10%,but without LA and LN(LA0+LN0).After feeding for 56 days,the fish whole body,the serum and the liver of sturgeon were sampled.Fish fed LA0+ LN0 and LA0+LN2.0 gained lowest weight but was not significantly different from the fish fed LA0+ LN1.0.Fish fed LA1.0+LN1.0 gained highest weight among all groups.Feed conversion ratio was the best in fish fed LA1.0+ LN1.0.Survival,condition factor and viserosomatic index did not differ among treatments.Total body n-6 fatty acids increased with the levels of n-6.Total body n-3 fatty acids also increased with dietary n-3,and fish fed 2.0%LN had the highest content of total body n-3 fatty acids among all groups.Triglyceride and cholesterol in the serum of fish fed LA 1.0+ LN1.0 were lowest.Fish fed LA1.0+ LN1.0 showed the highest lipoproteinlipase and lipase activities,but the lowest malate dehydrogenase activity.Fish fed LA1.0+ LN1.0 showed higher catalase,superoxide dismutase activity and total antioxidant capacity than fish fed other diets.This study indicates that diets containing both LA and LN are best for the growth of Russian sturgeon.The level of LA1.0+LN1.0 in the diet is most beneficial for growth performance and antioxidant capacity in juvenile Russian sturgeon.3.Dietary linolenic acids requirement of juvenile Russian sturgeonThis study conducted the linolenic acids(LN)requirement of juvenile Russian sturgeon.The initial weights of sturgeons were about 11.68±0.13g.The levels of linolenic acids in diets were designed by linseed oil as follow,0%,0.5%,1.0%,1.5%and 2.0%.After feeding for 8 weeks,the fish fed 0.5%and 1.0%LN got the highest weight gain and specific growth ratio,and lowest feed conversion ratio.The group fed 2.0%LN got the lowest weight gain.And the feed conversion ratio was highest at the group fed 0%LN.There had no significant differences in survival ratio,viserosomatic index and hepatosomatic index among all groups.Analysis of quadratic broken line model showed that the dietary LN requirement of sturgeon for growth was 0.69%.Fish fed 0.5%LN got the lowest MDA content,and the fish fed 1.0%got the highest.The activities of CAT got the similar trend with MDA.The activity of SOD was highest in fish fed 0.5%among all groups.The fish fed 0.5%LN had the higher T-AOC than fish fed 1.5%and 2.0%LN.Fish fed 0.5%LN got the highest MDH activity and the lowest LPL activity.The activity of LPS in 0.5%group was lower than 1.0%and 2.0%groups.Total body n-3 fatty acids also increased with dietary n-3.The TG and CHO in serum of fish fed 2.0%was higher than other groups.Fish fed 0.5%LN had the lowest CHO and LDL content of all.There were no significant differences in HDL among all groups.The real-time quantitative PCR showed that △6 Fatty acid desaturase(△ 6 FAD)and elongases of very long chain fatty acids 5(ELOVL5)genes were expressed higher with the increasing LN contents in diets.In conclusion,the optimal content in diet of LN for Russian sturgeon was between 0.5%to 1.0%.When comes to weight gain,the most optimal LN content was 0.69%.4.Dietary linoleic acids requirement of juvenile Russian sturgeonThis study conducted the linolenic acids(LA)requirement of juvenile Russian sturgeon.The initial weights of sturgeons were about 11.66±0.14g.The levels of linoleic acids in diets were designed by sunflower oil as follow,0%,0.5%,1.0%,1.5%,2.0%and 2.5%.After feeding for 8 weeks,the fish fed 1.0%got the highest weight gain and specific growth ratio,and the fish fed 2.5%LA got the lowest.The feed conversion ratio was lower in fish fed 1.0%than 0%,2.0%and 2.5%.There were no significant differences among 1.0%,0.5%and 1.5%in feed conversion ratio.Fish among all groups has no significant in survival ratio,viserosomatic index,hepatosomatic index and condition factor.Analysis of quadratic broken line model showed that the dietary LA requirement of sturgeon for growth was 1.15%.The content of MDA in serum of fish fed 1.0%and 1.5%was lower than 2.5%,and had no significant differences between other groups.The activity of SOD in fish fed 1.0%was lowest among all groups.The fish fed 1.5%LA got the lowest activity of CAT.The T-AOC showed the highest in fish fed 1.0%,and lowest in 0%.The content of TG and CHO in serum were increasing first,and then decreasing as the content of LA in diets increasing,and peaked at 1.5%LA.The content of LDL was higher than others in 1.5%LA,and the group of 0.5%LA was the lowest.There were no significant differences in content of HDL among all groups.The fish fed 1.0%got the highest activities of LPS and LPL.The activity of MDH in fish fed 1.0%was significantly lower than fish fed 2.0%,and had no significant difference with 1.5%.The real-time quantitative PCR showed that A6 Fatty acid desaturase(△6 FAD)and elongases of very long chain fatty acids 5(ELOVL5)genes were expressed higher with the increasing LA contents in diets.The results showed that the most optimal LA requirement of Russian sturgeon was 1.0%-1.5%.When comes to weight gain,the content of LA was 1.15%in diet,was most beneficial for growth of sturgeon.5.Optimal linolenic and linoleic ratio of juvenile Russian sturgeonThis study conducted the optimal linolenic and linoleic ratio of juvenile Russian sturgeon.The initial weights of sturgeons were about 11.67±0.12g.This study last for eight weeks.Lauric acid was replaced by sunflower oil and linseed oil to make five LA/LN diets(G1-0,G2-1,G1-1,G1-2,G0-1).The results showed that fish fed G2-1 got the highest weight gain and specific growth ratio among all groups,and the fish fed G1-2 and G0-1 got the lowest.The feed conversion ratio showed lowest in G2-1 group,and highest in G1-0 and G0-1 groups.There were no significant differences in viserosomatic index,hepatosomatic index and condition factor.The content of MDA in serum showed the lowest in fish fed G2-1,and had no significant differences with fish fed G0-1.Fish fed G2-1 and G1-1 got the highest SOD activities and T-AOC.Fish fed G1-1 got the highest CAT activity,and the G1-2 got the lowest.There were no significant differences among G1-0,G1-2 and G0-1 in T-AOC.Fish fed G0-1 got the highest MDH activity,and G1-0 and G0-1 got the lowest.The activity of LPL in liver showed highest in G2-1,and lowest in G1-1.The activity of LPS showed highest in fish fed G2-1 and G1-2,when the fish fed G1-0 and GO-1 showed the lowest.The content of TG and LDL in serum of fish fed G2-1 and G1-0 showed lower than others.The content of CHO in G2-1 group was the lowest among all groups,and the G1-2 was the highest.There were no significant differences in HDL content among all groups.The real-time quantitative PCR showed that A6 Fatty acid desaturase(△6 FAD)were expressed highest in fish fed G2-1,and lowest in fish fed G1-0,but there were no significant differences with GO-1.The real-time quantitative PCR of elongases of very long chain fatty acids 5(ELOVL5)genes showed highest in G2-1,lowest in GO-1.And there were no significant differences between G2-1 and G1-2.In conclusion,when the LA/LN ratio was 2:1 in diet,was the most optimal for the growth performance,antioxidant status and lipid metabolism of Russian sturgeon juvenile.6.Effects of different n-3 HUFA contents in diets on growth performance,antioxidant status and lipid metabolism of Russian sturgeonThis study aimed to find the optimal content of n-3 HUFA in diet for Russian sturgeon juvenile.The initial weight of sturgeon was 7.42±0.73.The n-3 HUFA was provided by fish oil to make five levels(0,0.3,0.6,0.9,1.2%)in diets.This study last for eight weeks.The content of lipid was 10%in diets.Also in diets had 1.0%linseed oil and 1.5%sunflower oil.Besides fish oil,lauric acid was as a supplement to reach the 10%lipid content.The results showed that there were no significant differences among fish fed 0.3,0.6,0.9 and 1.2%n-3 HUFA in weight gain,and significantly higher than fish fed diet without fish oil.Fish fed 0.3%n-3 HUFA got the lowest feed conversion ratio,and the 0.9%group got the highest.Condition factor showed higher in fish fed 0.3%than 0.9%,and there were no significant differences between 0.3%group and others.Survival ratio,viserosomatic index and hepatosomatic index showed no significant differences among all groups.Fish fed 0.9%n-3 HUFA had highest content of MDA in serum,and there were no significant differences among others.The content of SOD in serum showed lower in fish fed 0%n-3 HUFA than others.Fish fed 0%and 0.9%n-3 HUFA got the lowest activity of CAT in serum,and the fish fed 0.3%got the highest.Fish fed 0%n-3 HUFA showed the lowest T-AOC among all groups,and there were no significant differences between others.The activity of MDH in liver showed lowest in fish fed 1.2%,and highest in 0.3%and 0.6%.The activity of LPL decreased by the decreasing of content of n-3 HUFA in diets.Fish fed 0%n-3 HUFA showed the highest,and the 0.9%and 1.2%showed the lowest.The activity of LPS in liver showed the highest in fish fed without fish oil,and lowest in fish fed 0.9%and 1.2%.The content of LDL in serum decreased by increasing of the content of n-3 HUFA in diets.Fish fed 0%n-3 HUFA showed the highest,and 1.2%group showed the lowest.There were no significant differences in contents of TG,CHO and HDL among all groups.In conclusion,n-3 HUFA was benefit for the growth of Russian sturgeon juvenile.With all of the results together,it indicated that the most optimal content of n-3 HUFA in diet of Russian sturgeon juvenile was about 0.3%-0.6%.