Effects Of Different Levels Of Dietary Vitamin A, C, E On Reproductive E Performance And Offspring Quality Of Tongue Sole (Cynoglossus Semilaevis)

This experiment objiective of tongue sole (Cynoglossus semilaevis) was toinvestigate the effect of dietary vitamin A, vitamin E and vitamin C on reproductiveperformance and offspring quality of tongue sole. The experiments were in indoorfloating water culture pool in2-3months before breeding season. During theexperimental period, water temperature ranged from19to25℃, salinity from30to33‰, pH from8.0to8.2, DO (dissolved oxygen) content was greater than5mg/L andillumination intensity from100to500lx. The results of these studies are shown asfollows:1. A10-weeks feeding experiment was conducted to investigate the effects of dietaryvitamin A on reproduction and offspring quality of tongue sole. The basal diet wassupplemented with0,20and100IU/g vitamin A (retinol acetate) to formulate threeexperimental diets Ac, Al and Ah. Results showed that female gonad mature rate ofAl and Ah groups (70.00%and72.73%respecvtively) was higher than that of Acgroup (54.55%), and the relative fecundity of Al group (1.57×105eggs/kg) was thehighest, followed by the Ah group (1.57×105eggs/kg) and the Ac group (1.00×105eggs/kg) was the lowest. With the increasing dietary vitamin A, hatching rate wassignificantly increased (P<0.05). Fertilization rate of Al and Ah groups wassignificantly higher than that of Ac group (P<0.05), but no significan difference wasobserved between Al and Ah groups. Buoyant eggs rate, larvae length, survival rate at3DPH larvae and survival activity index of larvae (SAI) of Al group wassignificantly higher than those of Ac and Ah groups (P<0.05). Buoyant eggs rate andlarvae length of Ah group were significantly higher than those of Ac group (P<0.05).Abnormal larvae ratio was increased with the increasing dietary vitamin A withoutsignificant difference (P>0.05). With the increasing dietary vitamin A, the vitamin Acontent of tissues and eggs and superoxide ismutase (SOD) activities in serum were significantly increased (P<0.05). Besides, the vitamin C content in eggs of Al and Ahgroups were significantly higher than that of the Ac group (P<0.05), and theoxidation resistance in eggs of Al and Ah groups was increased. The contents ofn-3HUFA, n-6PUFA and PUFA in the fatty acid of eggs of Al and Ah groups werehigher than those of Ac group. This experiment demonstrated that the proper amountof vitamin A supplemented in the diet of broodstock could promote the developmentof gonad and improve the quality of eggs and larvae．The broodstock of Al group (20IU/g) had the best reproductive performance compared with the Ac and Ah groups inthis study.2. A10-weeks feeding experiment was conducted to investigate the effects of dietaryvitamin E on reproduction and offspring quality of tongue sole. The basal diet wassupplemented with0,200and1200mg/kg vitamin E (DL-α-tocopherol acetate) toformulate three experimental diets Ec, El and Eh. Results showed that female gonadmature rate of El and Eh groups was higher than that of Ec group. Relative fecundity,buoyant egg ratio, fertilization rate, hatching rate ratio and larvae length of Eh groupwere significantly higher than those of Ec group (P<0.05). Larvae survival rate,larvae length at12days post hatching and SAI of Eh group were also higher thanthose of Ec group. The development of gonad and larvae length in diet supplementedwith200mg/kg vitamin E (El group) was improved compared with that of Ec group(P<0.05), but the relative fecundity, buoyant egg ratio, fertilization rate and hatchingrate ratio in El group were not significantly different compared with those of Ecgroup (P>0.05). With the increasing dietary vitamin E, SOD activities in serumsignificantly increased (P<0.05), and MDA content significantly reduced (P<0.05). Inaddition, vitamin E supplemented in the broodstock diet increased the dry matter andvitamin C contents of eggs and PUFA, n-3PUFA, n-3HUFA and n-6PUFA contents inlipids of eggs. This experiment demonstrated that the high dose vitamin E (1200mg/kg) supplemented in the diet of broodstock could promote the development ofgonad and improve fecundity and quality of eggs and larvae．3. A2-months feeding experiment was conducted to investigate the effects of dietaryvitamin C on reproduction and offspring quality of tongue sole. The basal diet wassupplemented with0.5%,1.0%and1.5%L-Ascorbate-2-Phosphate to formulate threeexperimental diets C0.5, C1.0and C1.5. Results showed that dietary vitamin C had notsignificant effects on female gonadal development, relative fecundity and sperm concentrations. With the increasing dietary vitamin C, buoyant eggs ratio andhatching rate were significantly increased (P<0.05), and abnormal larvae ratio wassignificantly reduced (P<0.05). Egg diameter, fertilization rate and larval length ofC1.0and C1.5groups were significantly higher than those of C0.5group (P<0.05), butno significan difference was observed between C1.0and C1.5groups. Big dropletdiamter of C1.5group was significantly higher than that of C0.5group. Estradiol andtestosterone contents in serum of C1.0and C1.5groups were significantly higher thanthose of C0.5group (P<0.05), but no significan difference was observed between C1.0and C1.5groups. There were an increasing tendency in vitamin C content of eggs andbuoyant eggs ratio with the increasing dietary vitamin C, but no significantdifferences were observed (P>0.05). Besides, dietary vitamin C could increasevitamin C content of tissues, enhance SOD activities of tissues, eggs and seminalfluid, and reduce MDA contents in tissues, eggs and seminal fluid. This experimentdemonstrated the high dose L-Ascorbate-2-Phosphate (1.5%) supplemented in thediet of tongue sole broodstock was advantageous to promote the synthesis of sexhormones, improve reproductive performance of broodstock and the quality of eggsand larvae, promote the development of fertilized eggs, and reduce the abnormallarvae ratio.