| Cholesterol is one of the essential nutrients in aquatic animals and plays an important role in maintaining growth and reproductive regulation.With the continuous development of large-scale breeding technology,although the lack of research on broodstock nutrition of Litopenaeus vannamei has become a “bottleneck” restricting the high-speed and efficient development of China’s shrimp industry,there are few studies on the effects of cholesterol nutrition on the growth and reproduction of L.vannamei.In this study,the techniques of nutrition,histology,molecular biology and modern omics were used to evaluate the optimal cholesterol content in fortified feed,by analyzing the effects and mechanisms of cholesterol levels on growth performance,antioxidant capacity,lipid metabolism,sex hormone secretion and ovarian development of female L.vannamei.Five kinds of isonitrogenous and isoenergetic feeds by adding 0%(control),0.5%,1%,2%,or 3%cholesterol were prepared.Female L.vannamei broodstocks(initial weight 39.5 ± 4.3 g)were fed these five experimental diets for 28 days.The main results and conclusions are as follows:1)Dietary supplementation of 1% cholesterol to the diet could significantly increase the weight gain and the growth performance of female shrimp.Moreover,it can significantly improve the total antioxidant capacity(T-AOC)and superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activities of the hepatopancreas.Meanwhile,transcription factors(Fox O,GST)were also coordinated to regulate the antioxidant system and improve the antioxidant capacity of female shrimp.2)Dietary supplementation of 1% cholesterol to the diet could significantly increase the gonadal index(GSI)in female shrimp and promote the deposition of yolk granules in the ovary.The contents of hepatopancreas triglyceride(TG)and total cholesterol(T-CHO)in the shrimp fed diet with 1% cholesterol were significantly accumulated.Also in this experimental group,and the secretion of estrogen(E2,PROG,MF)was significantly increased than shrimp fed the other experimental diets by upregulating the genes expression of Vg,Vgr,St AR3,3β-HSD,17β-HSD and ERR which related to the steroid hormone synthesis pathways.3)Correlation analysis of serum metabolomics and ovarian transcriptomics found those significantly differently metabolites and differentially expressed genes were commonly enriched in the glutathione metabolism pathway significantly.This pathway further enhances the antioxidant capacity of shrimp with GSTs and may promote steroid hormone synthesis.Meanwhile,the correlation analysis of metabolites,genes and biochemical indexes showed that 3β-HSD and 17β-HSD were significantly positively correlated with E2 and MF,respectively.There was a significant positive correlation between Linoleic acid and PROG,while a significant negative correlation between Pro-leu and PROG.The differentially expressed gene LOC113827313 was also positively correlated with PROG and regulated by differential metabolite Linoleic acid.In conclusion,the dietary supplementation of 1% cholesterol can significantly promote ovarian development and strengthen antioxidant system of female L.vannamei.To improve reproductive performance and health status,it is suggested that the appropriate dietary cholesterol supplementation level for female broodstock of L.vannamei is 1.606%-1.680%. |
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