饲料中DHA与EPA比例对星斑川鲽雌鱼性类固醇激素及繁育性能的影响

Effects of DHA and EPA ratios in dietary on sex steroid hormone andreproduction performance in female starry flounder(Platichthys stellatus)

为了探索饲料中DHA与EPA比例对星斑川鲽(Platichthys stellatus)雌性亲鱼繁育性能的影响,配制等氮等脂含不同DHA与EPA比例(0.65、1.33、2.12、3.08和3.92)饲料5组,每组设3重复,室内循环水系统养殖,试验周期90 d,试验结束后取亲鱼血清及性腺检测。结果表明,随着饲料DHA与EPA比值的升高,亲鱼雌二醇(E 2)呈先升后降趋势,DHA与EPA比值为1.33时,促进作用显著(P<0.05)。性腺中FSHR、StAR和芳香化酶表达量也显著高于对照组(P<0.05);添加DHA和EPA后亲鱼的绝对繁殖力显著提高,但DHA与EPA比值为1.33效果更显著(P<0.05);在DHA与EPA比值为0.65、1.33组和2.12时,雌鱼性腺中单不饱和脂肪酸的含量显著高于其他组(P<0.05),n-6多不饱和脂肪酸出现显著下降(P<0.05),n-3多不饱和脂肪酸明显上升,差异显著(P<0.05)。由此可见,饲料中添加DHA和EPA能有效促进星斑川鲽雌性亲鱼的性腺发育,DHA与EPA比值为1.33时能提高亲鱼E 2分泌,FSHR、StAR和芳香化酶表达以及单不饱和脂肪酸的吸收,增加性腺发育能量供给,促进亲鱼性腺成熟,提高繁育性能。

In order to investigate the effects of docosahexaenoic acid(DHA)and eicosapentaenoic acid(EPA)ratios in dietary on sex steroid hormone and reproduction performance in female starry flounder(Platichthys stellatus),five isonitrogenous and isolipidic experimental diets were formulated to contain different DHA and EPA ratios(0.65,1.33,2.12,3.08 and 3.92),each group has 3 duplication.Fish were reared in an indoor flowing seawater system and lasting 90 d.At the end of the feeding trial,sex steroid hormone production was assayed and gonad samples from females were collected to determine the gene expressions of sex steroid-synthesizing proteins.The results showed that the estradiol production in females increased and then decreased with higher DHA and EPA ratios,promotion significantly and increased the mRNA expression of FSHR、StAR and aromatase in ovaries significantly when DHA and EPA ratios at 1.33(P<0.05).Female broodstock gonadosomatic index,absolute fecundity,relative fecundity increased significantly after adding DHA and EPA,and obtained better results in DHA and EPA ratios group 1.33 compared with the control group.In ovaries,the content of monounsaturated fatty acids(MUFA)in group 0.65,1.33 and 2.12 was significantly higher than other groups(P<0.05);Meanwhile n-6 polyunsaturated fatty acid(PUFA)decreased significantly compared to the control group and n-3 PUFA increased significantly as well(P<0.05).In conclusion,DHA and EPA adding promoted female starry flounder gonad development and increased the estradiol production in females effectively.The mRNA expression of FSHR、StAR and aromatase and absorption of MUFA and increased the energy supply of gonad development only when DHA/EPA ratios at 1.33 as well as promoting the maturation of the gonads and improving reproduction performance of females.