Effects of dietary phospholipids and highly unsaturated fatty acids on the precocity, survival, growth and hepatic lipid composition of juvenile Chinese mitten crab, Eriocheir sinensis (H. Milne-Edwards)

Abstract

Precocious puberty is one of the major constraints to the further development of Chinese mitten crab (Eriocheir sinensis) farming industry. Although dietary phospholipids (PL) and highly unsaturated fatty acids (HUFA) supplementation have been shown to enhance the growth of larval E. sinensis in other studies, it is still unknown whether this also leads to a higher precocity rate for juvenile E. sinensis. This study was conducted to investigate the e¡ects of dietary PL and HUFA on precocity, survival, growth and hepatic lipid composition of juvenile E. sinensis. Two diets were formulated with PL [3.95% dry weight (DW)] and HUFA (0.98% DW) supplementation (diet A) and without PL and HUFA supplementation (diet B) and fed to juvenile E. sinensis. Although dietary PL and HUFA levels did not signi¢cantly a¡ect the survival and growth performance of juvenile E. sinensis, compared with crabs fed diet A, a higher precocity rate was found among juvenile E. sinensis fed diet B (P 5 0.051). A higher total lipid content, but sig-ni¢cantly lower levels of HUFA and PL (Po0.05) were found in the hepatopancreas of crabs fed diet B than in those fed diet A. Meanwhile, the precocious females had signi¢cantly lower hepatosomatic index , arachidonic acid (20:4n-6), eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) contents in their hepatopancreas when compared with that of the normal immature juveniles (Po0.05). The results suggest that the occurrence of precocious puberty among farmed juvenile E. sinensis could be reduced by the inclusion of appropriate level of dietary PL and HUFA. Ã Vitamin mix: 1kg of diet contained vitamin A 10 000 IU; vitamin D 2500 IU; vitamin K 64 mg; thiamin 60 mg; ribo£avin 250 mg; pyridoxine 60 mg; a-tocopherol acetate 500 mg; L-ascorbic acid 4.5 g; calcium panthothenic 240 mg; niacin 60 mg; folic acid 12 mg; biotin 50 mg; cyanocobalamine 4 mg. wMineral mix: 1kg of diet contained Ca(H 2 PO 4 ) 2 10 g; MgSO 4 Á 7H 2 O 2.4 g; KCl 4.5 g; NaCl 2.1g; FeSO 4 Á H 2 O 155 mg; CuSO 4 Á 5H 2 O 40 mg; ZnSO 4 Á H 2 O 80 mg; MnSO 4 Á H 2 O 30 mg; KI 11.7 mg; CoCl 2 Á 6H 2 O 4.8 mg; Na 2 SeO 3 2.4 mg. Bold highlights the level di¡erence between two diets. Aquaculture Research, 2011, 42, 457^468 Dietary PL and HUFA on the precocity of juvenile Eriocheir sinensis X Wu et al. r

Does the wild-caught Chinese mitten crab megalopae perform better than the hatchery-produced seed during the juvenile culture?

“…Survival is an important criterion for the evaluation of culture performance of aquatic animals (Wu et al., ). This study showed WC had a lower survival rate than HP, which could be due to the large variation in body weight and aggressive behaviour of juveniles from the WC population.…”

“…The precocious crabs, weighing between 15 and 35 g, have a low market value. Because precocious crabs have completed the terminal moult and reached precocious puberty, they are usually not used for stocking the grow‐out ponds in the following years (Wu et al., ). This has serious impacts on the economic profit of the E. sinensis farming industry (Li et al., ).…”

“…During the first year of juvenile culture, precocious puberty is one of the major constraints for the improvement of culture performance of E. sinensis , since precocious crabs are small (15–35 g/ind.) and generally have little market value (Wu et al., ).…”

A mixture of fish oil and soybean oil as a dietary lipid source prevents precocity and promotes growth in juvenileMacrobrachium nipponense(De Haan)

“…Except improving growth, proper dietary fatty acid composition can also prevent the occurrence of precocity in crustacean (Lu et al . ; Wu, Wang, Cheng, Zeng, Yang & Lu ). In M. nipponense, the optimal dietary lipid content has been reported as 6–12% (Yu & Shen ), but the effects of lipid sources on growth and precocity have not been studied yet.…”

“…Soybean oil containing high n-6 polyunsaturated fatty acids (PUFA) was regarded to promote growth in leader prawn and red claw crayfish (Deering et al 1997;Li, Guo, Gan, Wang, Zhang & Zhao 2011), but in Penaeus vannamei and Litopenaeus vannamei, fish oil containing high n-3 highly unsaturated fatty acids (HUFA), such as 20:5n-3(EPA) and 22:6n-3(DHA), had better effect in promoting growth (Lim, Ako, Brown & Hahn 1997;Gonz alez-F elix, Lawrence, Gatlin & Perez-Velazquez 2002). Except improving growth, proper dietary fatty acid composition can also prevent the occurrence of precocity in crustacean (Lu et al 2010;Wu, Wang, Cheng, Zeng, Yang & Lu 2011). In M. nipponense, the optimal dietary lipid content has been reported as 6-12% (Yu & Shen 1990), but the effects of lipid sources on growth and precocity have not been studied yet.…”