维生素C对半滑舌鳎亲鱼繁殖性能及后代质量的影响

Effects of Vitamin C on Reproductive Performance and Offspring Quality of Tongue Sole(Cynoglossus semilaevis) Broodstocks

本试验旨在研究维生素C对半滑舌鳎亲鱼繁殖性能及后代质量的影响。在基础饲料中分别添加0.5%(C0.5组)、1.0%(C1.0组)和1.5%(C1.5组)的L-抗坏血酸-2-磷酸酯(作为维生素C添加剂),制成维生素C添加量分别为0.175%、0.350%和0.525%的3种试验饲料。每种试验饲料饲喂3.5龄滑舌鳎雌性亲鱼15尾[(1.15±0.11)kg/尾]和雄性亲鱼20尾[(0.25±0.05)kg/尾],饲喂2个月后人工育苗。结果表明:添加维生素C对半滑舌鳎雌性亲鱼的性腺指数和相对产卵量以及雄性亲鱼的精液浓度没有显著影响(P>0.05),添加0.350%维生素C能显著提高雄性亲鱼的性腺指数(P<0.05)。随饲料中维生素C添加量的增加,上浮卵率和孵化率显著上升(P<0.05),初孵仔鱼畸形率显著下降(P<0.05)。C1.0和C1.5组的卵径、受精率、初孵仔鱼体长以及血清中雌二醇和睾酮含量均显著高于C0.5组(P<0.05),而C1.0与C1.5组之间无显著差异(P>0.05)。C1.5组卵中大油球直径显著高于C0.5组(P<0.05)。卵子和上浮卵中维生素C含量随饲料中维生素C添加量的增加呈上升趋势,但各试验组间无显著差异(P>0.05)。此外,饲料中添加维生素C能不同程度地提高亲鱼肝脏、卵巢、精巢和卵子中维生素C含量,提升亲鱼血清、肝脏、卵巢、精巢、卵子和精液中超氧化物歧化酶活性并相应降低丙二醛含量。由此可见,本试验条件下,饲料中添加高剂量(0.525%)的维生素C更有利于促进半滑舌鳎亲鱼性激素的合成,改善亲鱼的繁殖性能,提高精卵质量,促进受精卵孵化,减少仔鱼畸形。

This study was conducted to investigate the effects of vitamin C on reproduction performance and offspring quality of tongue sole （ Cynoglossus semilaevis） broodstocks. Three experimental diets were prepared by adding 0.5% （C0.5 group） , 1.0% （C1.0 group） and 1.5% （C1.5 group） L-ascorbate-2-phosphate （ as vita- min C additive） into the basal diet, and the vitamin C supplemental levels in the 3 experimental diets were 0.175%, 0.350% and 0.525%, respectively. Fifty 3.5-year-old female broodstocks [ （ 1.15±0.11 ） kg/fish and twenty 3.5-year-old male broodstocks [ （1.15±0.11 ） kg/fish ] of tongue sole were fed one of three experi- mental diets for 2 months, and then artificial reproduction. The results showed that the supplementation of vita- min C had no significant effects on the gonadal index and relative fecundity of female broodstocks and the sperm concentration of male broodstocks （P〉0.05）, and the supplementation of 0.350% vitamin C could sig- nificantly increase the gonadal index of male broodstocks （P〈0.05）. With the vitamin C supplemental level in- creasing, buoyant egg ratio and hatching rate were significantly increased （P〈0.05）, while newly-hatched lar- val malformation ratio was significantly reduced （ P〈 0.05 ）. Egg diameter, fertilization rate, newly-hatched larval body length and the contents of estradiol and testosterone in serum of C1.0 and C1.5 groups were signifi- cantly higher than those of C0.5 group （P〈0.05） , but no significant differences were observed between C1.0 and C1.5 groups （P〉0.05）. There was an increasing tendency in vitamin C content in egg and buoyant egg with the vitamin C supplemental level increasing, but no significant differences were observed among all experimental groups （P〉0.05）. Besides, the supplementation of vitamin C could increase the vitamin C content in liver, ovary, testicle and egg, enhance the superoxide dismutase activity in serum, liver, ovary, testicle, egg and seminal fluid, and reduce the malondialdehyde content, correspondingly. The results demonstrate that the high dose （ 0.525% ） vitamin C supplemented in the diet of tongue sole broodstocks is advantageous to promote the synthesis of sex hormones, improve the reproductive performance of broodstocks and the quality of egg and sperm, promote the development of fertilized egg, and reduce the malformation of larvae under this experimental condition.