Abstract:Tongue sole Cynoglossus semilaevis has high economic values and is extensively exploited in northern China. However, there have been few reports on the broodstock nutritional requirements of this species. In this study we investigated the effects of dietary taurine on the reproductive performance, the antioxidant function, and the egg and larval qualities of tongue sole C. semilaevis. Three experimental diets containing different levels of taurine (control T-0, T-0.5 and T-1.5%) were formulated and randomly distributed into three 3 m×2.5 m×1.2 m cement ponds with 15 females and 20 males in each for 9 weeks. Dietary taurine (0.5%) improved the relative fecundity and boosted the secretion of testosterone and estradiol in tongue sole broodstock (P<0.05). Moreover, compared to T-0, the T-0.5 diet significantly elevated the buoyant egg rate, the fertilization rate, the hatching rate, the egg diameter, the oil droplet diameter, and the larval length at 3 DPH and 7 DPH (P<0.05). The broodstock fed with the control (T-0) diet exhibited higher abnormal rate than the other two groups (P<0.05), and there was no significant difference in larval survival activity index (SAI) among the different dietary treatments (P>0.05). The concentrations of taurine in the liver and the gonad were increased and the activity of cysteamine dioxygenase was decreased along with the increase in dietary taurine. Compared to the control group, the activity of superoxide dismutase (SOD) in the liver, the serum, the testis, and the semen was also significantly higher in broodstock fed with T-0.5 diet (P<0.05), and the level of malondialdehyde (MDA) in the gonad and the eggs were significantly lower (P<0.05). In conclusion, these results suggested that dietary taurine may have considerable effects on the reproductive performance, the antioxidant function, and the egg and larval quality of C. semilaevis, and that the optimal concentration of taurine in the diet should be 0.5%.
