Effects of Different Levels of Dietary Vitamin E on the Reproductive Performance and Offspring Quality of Tongue Sole Cynoglossus semilaevis

Abstract:

In this study we investigated the effects of vitamin E on the reproduction and the egg quality of tongue sole Cynoglossus semilaevis. Broodstock were fed for 10 weeks with diet groups Ec, El and Eh that were supplemented with 0, 200 and 1200 mg/kg vitamin E (DL-α-tocopherol acetate) respectively. The results showed that subjects in the Eh group (1200 mg/kg Vitamin E) displayed advantageous development of gonad, and improvement in the relative fecundity, buoyant egg ratio, fertilization rate, hatching rate ratio and larvae length, as well as higher quality of larvae. The larvae survival rate, larvae length at 12 days post hatching and survival activity index of larvae (SAI) of the Eh group were higher than those in the Ec group (P<0.05). The development of gonad and the larvae length in the El group (200 mg/kg vitamin E) were promoted, however the fecundity, buoyant egg ratio, fertilization rate and hatching rate ratio were not changed compared to those in the Ec group (P>0.05). Along with the increase in dietary vitamin E, the activity of superoxide ismutase (SOD) in serum was significantly increased and the level of malonaldehyde (MDA) was reduced (P<0.05). The levels of dry matter and vitamin C in eggs were significantly higher in the El and Eh groups (vitamin E supplementation groups) than in the Ec group (P<0.05), but there was no difference between the El and Eh groups. Furthermore, the addition of vitamin E in the diet also increased the levels of PUFA, n-3PUFA, n-3HUFA and n-6PUFA in eggs and thus improved the egg quality. These results demonstrated that vitamin E supplemented in the diet could promote the development of gonad and improve the fecundity, the quality of eggs and larvae of tongue sole, and that 1200 mg Vitamin E per kg was optimal for the reproductive performance of tongue sole.