Search

Cholesterol is an important component of fresh biological baits and essential precursor to synthesize steroid hormones for crustacean. However, the cholesterol demand in Pacific white shrimp broodstock and its roles on ovary development and reproductive capacity are unknown. In the present study, female Pacific white shrimp broodstock (initial weight 51.3 ± 0.5g) were fed with three diets contained 0.5%, 1% or 1.5% cholesterol for 45 days. The results found that dietary cholesterol levels did not affect survival rate, weight gain, egg-laying number, vitellogenin content and vitellogenin receptor gene expression in the hepatopancreas. However, the hepatosomatic index, gonadosomatic index, egg diameter, vitellogenin level in the ovary and fertilized egg, C22:6n-3 (DHA) level in the fertilized egg, total protein, triglyceride and cholesterol contents were all increased in the 1.0% and 1.5% cholesterol groups than those in the 0.5% cholesterol group. Moreover, compared with the 0.5% and 1.0% cholesterol groups, the 1.5% cholesterol group had significantly higher gonad maturation number, mating rate, estradiol level in the hemolymph, steroid hormones synthesis related genes (HMGCR, StAR, 17βHSD and 1vMFBP) expression in the ovary and hepatopancreas. In conclusion, dietary 1.5% cholesterol could promote ovary development and reproductive capacity in female Litopenaeus vannameibroodstock by improving nutrients accumulation and steroid hormones synthesis pathway. Our results provide guidance for design of artificial compound feed and healthy development of shrimp broodstock farm.

Starvation is a natural process in the life cycle of wild fish, and also a means of body composition regulation for farmed fish. This study with tiger puffer was aimed at investigating the effects of starvation on lipid and fatty acid compositions in fish with different levels of lipid accumulation. Different lipid accumulation levels in tiger puffer were obtained by manipulating the dietary lipid content (8%, 12%, and 16%) in a previous feeding period for 9 weeks. Each diet was fed to sextuplicate net cages in this feeding trial. At the end of the feeding trial, fish with an average initial body weight of 68.26g were then subjected to starvation for 31 days. Tissue samples were collected at the end of the feeding trial and at 1, 4, 9, 16, and 31 days after starvation. The results showed that the muscle lipid content decreased linearly with starvation time, but the liver lipid content increased firstly (1-16 days of starvation), and thereafter sharply declined. However, no interaction between starvation time and dietary lipid level was observed in the effects on liver and muscle lipid composition. Starvation had slight effects on muscle and liver fatty acid compositions, except that it largely increased the C22:5n-3 content in the muscle. Starvation primarily mobilized C14:0, C16:1n-7, C20:1n-9 and C22:1n-9 in the muscle, and C18:0, C18:1n-9, and EPA in the liver. Interactive effects between starvation time and dietary lipid level were observed for many fatty acids. Short-term (1-4 days) starvation increased the muscle texture parameters, but longer-term starvation decreased them. In conclusion, starvation exerts significant effects on lipid and fatty acid composition in farmed tiger puffer. Customed lipid and fatty acid composition, and possibly customed fillet quality could be obtained through manipulation of starvation time and dietary lipid level in the previous feeding period.

•To tiger puffer, FPH supplementation in plant protein based diets was able to save fish meal.•The response of amino acid and peptide transporters in the FPH supplementation group was similar to the HFM group.•FPH supplementation in diets not only affected muscle protein synthesis, but also affected muscle texture.

•The coding sequence and 3′- untranslated region of Takifugu rubripes mid1ip1was cloned.•Tiger puffer mid1ip1, putatively mid1ip1subtype B, is highly expressed in the muscle and skin.•The hepatic gene expression of mid1ip1was regulated by dietary bile acid, but not by dietary lipid level.•This mid1ip1subtype may have potential roles in microtubule stabilization, but have limited functions in lipogenesis.