Investigation Of The Effct Of Different Sterol Sources Of Feed On Growth,Lipid Metabolism,Hormone Secretion And Early Gonad Development Of Juvenile Redclaw Crayfish,Cherax Quadricarinatu

In the process of modern industrial farming,the redclaw crayfish,Cherax quadricarinatus,face problems such as large differences in cell maturation of female crayfish egg cell maturation,small spawning amount,low hatchability and survival rate due to lack of nutritional precision needs,red crayfish are in a state of oxidative stress for a long time,growth and breeding are inhibited,and even reduced immunity leads to disease outbreaks.Male crayfish also have sperm malformations and germplasm degradation problems due to lipid nutritional imbalance.This leads to damage to the output value and affects the large-scale development of crayfish aquaculture industry.Lipid nutrition plays an important role in aquatic animals,and can provide the energy needed for growth and gonadal development,among which sterol nutrition is an important derived lipid,which can improve lipid accumulation and promote the rapid development of aquatic animals.Since crustaceans cannot synthesize cholesterol de novo,exogenous sterols must be ingested,and the red crayfish is a phytovorous species.Therefore,the addition of sterols to the feed can improve the nutritional parameters of red crayfish,and the development of professional crayfish special feed provides theoretical research.However,sterols from different sources have different effects on aquatic animals,and the same sterol has different effects on different aquatic animals.At present,studies on sterol nutrition from different sources in crayfish have not been reported.This study aims to use cholesterol,ergosterol,β-sitosterol and fucosterol as four different sources of sterols to set up the experimental group,and the feed without sterols as the control group,respectively,with male and female red crayfish as experimental objects,through growth,lipid metabolism and hormone secretion to screen out the most suitable sterol sources suitable for the growth of male and female crayfish,respectively,and determine the next research direction of sterol nutritional regulation through metabolome metabolic pathway analysis.The main research contents and results are as follows:1.Effects of different sterol sources in feed regulating growth,lipid metabolism,hormone secretion and early gonadal development of female red crayfishCholesterol,ergosterol,β-sitosterol and fucosterol were added to female red crayfish,and the sterol-free group was used as the control for 8 weeks,and the results showed that: The weight gain and specific growth rate of crayfish fed diet with ergosterol were significantly higher than those of crayfish fed with cholesterol,fucosterol and control diets,but there was no significant difference with β-glutamol group.The hepatosomatic index of crayfish in the control was significantly higher than crayfish fed diets with ergosterol and β-sitosterol.The total cholesterol content of hepatopancreas in crayfish fed with cholesterol diet was significantly higher than that in other experimental groups,and the content of triacylglycerol in hepatopancreas was the lowest in crayfish fed with fucosterol diet.There was no significant difference in the content of total cholesterol in the ovary of crayfish among all experimental groups,but the content of triglyceride in fucosterol group was significantly higher than that in other experimental groups.Crayfish fed with β-sitosterol diet had the highest content of serum very low-density lipoprotein,but also had the lowest activity of Hepatopancreatic3-hydroxy-3-methylglutaryl-Co A reductase.Crayfish fed diet with β-sitosterol had the highest serum progesterone,testosterone,estradiol,methyl-farnesoate and cyclooxygenase-1 activity,but the lowest serum aromatase activity and gonadal inhibitory hormone content.Basis on the analysis of serum metabonomics,in the early stage of gonadal development of female crayfish,β-sitosterol intake can promote the development of ovarian tissue by improving galactose metabolism,pyrimidine metabolism,phenylalanine metabolism,phenylalanine,tyrosine and tryptophan biosynthesis.In conclusion,plant-source ergosterol could significantly increase the rate of early gonadal development of female crayfish,and plant-source β-sitosterol could significantly increase the content of sex hormones in crayfish.However,algae-source fucosterol and animal-source cholesterol did not play a significant positive role in the early gonadal development stage of crayfish.2.Effects of different sterol sources in feed regulating growth,lipid metabolism,hormone secretion and early gonadal development of male red crayfishCholesterol,ergosterol,β-sitosterol and fucosterol were added to male red crayfish,and the sterol-free group was used as the control for 8 weeks,and the results showed that: The weight gain and specific growth rate of crayfish fed diet with ergosterol and β-sitosterol were significantly higher than those of crayfish fed with cholesterol,fucosterol and control diets,but there was no significant difference with β-glutamol group.The condition factor in β-sitosterol was significantly lower than control、cholesterol and fucosterol.The hepatosomatic index between experimental diet was insignificant.The gonadsomatic index of crayfish in the control was significantly higher than crayfish fed diets with β-sitosterol、ergosterol and fucosterol.The total cholesterol content of hepatopancreas in crayfish fed with cholesterol diet was significantly higher than that in other experimental groups,The total cholesterol in fucosterol wasi significantly higher than control.Crayfish fed with β-sitosterol diet had the highest content of serum very low-density lipoprotein,and fed diet with β-sitosterol had the highest serum progesterone,estradiol,methyl-farnesoate and cyclooxygenase-1 activity,but the lowest serum aromatase activity and gonadal inhibitory hormone content.The fucosterol possess the lowest testosterol content.Basis on the analysis of serum metabonomics,In the stage of gonad development of male crayfish,the intake of β-sitosterol can promote the development of testis by improving biosynthesis and metabolism.In conclusion,plant-source ergosterol and β-sitosterol could significantly increase the growth of male crayfish,and plant-source β-sitosterol could significantly increase the content of sex hormones in male crayfish.However,algae-source fucosterol and animal-source cholesterol did not play a significant positive role in the early gonadal development stage of male crayfish.