Effects of dietary vitamin A supplementation on the reproduction and offspring quality of tongue sole Cynoglossus semilaevis

Abstract:

This study evaluated the effects of vitamin A supplementation on the reproduction and offspring quality of tongue sole Cynoglossus semilaevis. Broodstock (females, average weight 1.58 kg; males, average weight 0.2 kg) were fed with one of the three diets (Ac, control, no vitamin A supplementation; Al, 20 IU/g vitamin A as retinol acetate; and Ah, 100 IU/g vitamin A as retinol acetate) for 10 weeks at water temperature of 19-25℃. Results showed that female gonad mature rates (GMA) in the Al and Ah groups were higher than that of the Ac group. The relative fecundity in the Al group was the highest (1.57×10⁵ ind./kg), while that in the Ac group was the lowest (1.00×10⁵ ind./kg). Hatching and fertilization rate in the Al and Ah groups were significantly higher than those in the Ac group (P<0.05). Buoyant eggs rate, larvae length, larvae survival rate and survival activity index of larvae (SAI) were the highest in the Al group. The dietary vitamin A supplementation increased the abnormal larvae ratio, but the effect was not significant (P>0.05). Vitamin A content in the tissues and eggs and activity of the superoxide dismutase (SOD) in serum were significantly increased with the increasing dietary vitamin A level (P<0.05). In addition, compared to those in the control group, vitamin C levels in the eggs were significantly higher in the two treatment groups (P<0.05); and the oxidation resistance of the eggs increased in the two treatment groups. The levels of n-3HUFA, n-6PUFA and PUFA in the eggs in the Al and Ah groups were all higher than those in the Ac group. These results demonstrated that the proper amount of vitamin A supplemented in the diet may promote the development of broodstock gonads and improve the quality of the eggs and larvae. The broodstock in the Al group (20 IU/g) had the best reproductive performance compared to those in the Ac and Ah groups．