无鱼粉无鱼油饲料喂养下大黄鱼幼鱼个体间生长及相关基因表达差异

Variations in Individual Growth and Related Genes Expression of Juvenile Larimichthys crocea Fed with Fish Meal and Fish Oil Free Diet

为了解大黄鱼个体间对无鱼粉无鱼油饲料的适应性差异,配制了无鱼粉无鱼油配合饲料对大黄鱼幼鱼(体重1.75~5.75 g)进行为期70 d左右的饲养,测定不同个体的生长状况、体组织脂肪酸组成,并用qRT-PCR技术检测高度不饱和脂肪酸(highly unsaturated fatty acids,HUFA)合成相关基因表达情况。结果表明:投喂无鱼粉无鱼油饲料饲养的大黄鱼幼鱼个体生长差异显著,各组最大个体体重是其同组最小个体的3~4倍;生长快个体肌肉中EPA含量较生长慢个体高,而DHA含量则相反(P<0.05),但两者之间ΣHUFA差异不显著;Elovl1、Elovl5、Elovl6和Δ6-Fad 4个基因在大黄鱼脑中表达量最高,其次是肝脏,在肌肉中表达量则最低;投喂无鱼粉无鱼油饲料饲养的生长快个体的脑中Elovl1和Δ6-Fad,肝中Elovl5、Δ6-Fad和Elovl1,以及胃和肠中Elovl1的表达量均极显著(P<0.01)或显著(P<0.05)高于生长慢个体。这说明大黄鱼不同个体之间营养需求或饲料选择性存在显著差异,因此,可通过遗传选育培育出对鱼粉鱼油需求量低的养殖品种。

This study was conducted to investigate the effect of fish meal and fish oil free formulated diet(FMFOFD)to different individuals on the growth,fatty acid compositions and highly unsaturated fatty acids(HUFA)synthesis related genes expression of juvenile Larimichthys crocea.The tested fish(initial weight were 1.75-5.75 g)were divided into six groups by body weight and fed with FMFOFD for 70 d.The results showed that there was a significant difference in the growth of the surviving juvenile fish in each group.The body weight of the maximum individual was 3-4 times of the smallest one,confirming that there was significant difference in nutritional requirements among different individuals.The HUFA content in the muscle of fish fed with FMFOFD was lower than those fed with commercial diet(CMD).In the FMFOFD feeding groups,compared with the slow-growing group,the fast-growing group had higher EPA content and lower DHA content(P<0.05),but there was no significant difference in the∑HUFA content between the two groups.qRT-PCR was used to compare the expression of several genes related to HUFA synthesis in the brain,liver,stomach,intestine and muscle in fish fed with CMD and FMFOFD.Elovl1,Elovl5,Elovl6 andΔ6-Fad were expressed the highest in the brain,followed by the liver,and have the lowest expression level in the muscle.Compared with CMD fish,fast-growing individals fed FMFOFD expressed higher Elovl1 andΔ6-Fad level in the brain,higher Elovl5 and Elovl1 in the liver,higher Elvol1 in the stomach and intestine than slow-growing individals,suggesting that the growth performance of juvenile large yellow croaker fed with FMFOFD may be related to the differential expression of those genes.The results of this study showed that there were significant differences in nutritional requirements or feed selectivity among different individuals of large yellow croaker.Therefore,it is promising to develop breeding varieties with low demand for fish meal and fish oil through genetic selection.