| This experiment investigated the effect of dietary taurine and krill meal on reproductive performance and larval quality of tongue sole. The experiments were in floating water culture pool, water temperature ranged from 19 to 25 ℃, salinity from 30 to 33 ‰, p H from 8.0 to 8.2, DO(dissolved oxygen) content was greater than 6 mg/L and illumination intensity from 100 to 500 lx. The results of these studies are shown as follows:1. Three experimental diets contain three levels of taurine(control T-0, T-0.5 or T-1.5%)were formulated to feed the broodstock, and they were randomly distributed into 3 3 m×2.5 m×1.2 m cement ponds with 15 females and 20 males per pond for 9 weeks. Results showed that, dietary 0.5% taurine can not only improve the relative fecundity, but also promote the secretion of testosterone and estradiol in tongue sole broodstock(P<0.05). The buoyant egg rate, fertilization rate, hatching rate, egg diameter, oil droplet diameter, larval length 3 DPH and 7 DPH were all higher in broodstock fed T-0.5 diet than those in T-0 groups(P<0.05). The broodstock fed the control(T-0) diet showed higher abnormal rate than that of 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 taurine content in liver and gonad were increased and the cysteamine dioxygenase activity was decreased with the dietary taurine level increasing. The superoxide dismutase(SOD) activities in livers, serum, testis, semen were significantly higher in broodstock fed T-0.5 diet than that of the control group(P<0.05), and the malondialdehyde(MDA) content in gonad and eggs were significantly lower than that of the control group(P<0.05). In conclusion, the present study suggested taurine in broodstock diet has a considerable effect on reproductive performance, antioxidant function, egg and larval quality for Cynoglossus semilaevis, and this study suggested that the optimal additive level of taurine was 0.5%.2. A 3-month feeding trial was conducted to investigate the effect of dietary krill in broodstock diets on reproductive performance, larval quality and antioxidant function of tongue sole Cynoglossus semilaevis. Three experimental diets contain three levels of krill meal(control K-0, K-10 or K-20%) were formulated to feed the broodstock. Results showed that, the hepatosomatic index, sex index, sperm concentration and testosterone contents had no significant differences in experimental groups(P>0.05), but dietary 10% krill can not only improve the relative fecundity, but also promote the secretion of estradiol were significantly improved in K-10 group of tongue sole broodstock(P<0.05). The buoyant egg rate, fertilization rate, hatching rate, egg diameter and oil droplet diameter were all higher in broodstock fed K-10 diet than those in K-0 groups(P<0.05). The superoxide dismutase(SOD) activities in semen and eggs had no significant differences between K-10 and K-20 group(P>0.05), but were significantly higher than that of the control group(P<0.05); The malondialdehyde(MDA) content in semen, serum and liver had no significant differences between K-10 and K-20 group(P>0.05), but were significantly lower than that of the control group(P<0.05). The larval length at 1 DPH, 3 DPH, 6 DPH and 11 DPH, survival rate at 3 DPH, SAI were significantly higher for the K-10 than K-0(P<0.05). The broodstock fed the control(K-0) diet showed higher abnormal rate than that of the other two groups(P<0.05). The amylase, lipase, protease activities at 6 DPH, protease activities at 15 DPH were higher in broodstock fed K-10 diet than those in K-0 groups(P<0.05). In conclusion, the present study suggested dietary krill meal has a considerable effect on reproductive performance, larval quality and antioxidant function for Cynoglossus semilaevis, and this study suggested that the optimal additive level of krill meal was 10%. |
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