【摘要】 研究了饲料中不同水平n-3 HUFA(0.79%,0.83%,0.85%,0.88%,0.92%,0.94%;DHA/EPA=2.8/1)对黑鲷幼鱼生长及脂肪代谢的影响。结果显示:(1)黑鲷幼鱼肝体指数(HSI)及腹脂率(IPF ratio)随饲料中n-3 HUFA含量的增加而减小,且于0.92%和0.94%组时显著低于其他各组;脂肪细胞直径呈减小趋势,其中0.94%组显著小于0.85%组;肌肉脂肪含量受n-3 HUFA的影响显著,于0.88%组时达到最低。各组全鱼水份和脂肪含量差异不显著(P>0.05)。肝脏、肌肉及腹腔脂肪组织饱和脂肪酸(∑SFA)和C16∶0含量均随饲料n-3HUFA水平增加呈下降趋势,而∑n-3 HUFA呈显著上升趋势。各组织中DHA/EPA不受饲料脂肪酸组成的影响。以增重率为参考指标,二次回归分析结果表明,黑鲷幼鱼[(8.08±0.09)g]获得最佳增重时对饲料中n-3 HUFA的需要量为0.87%DM;(2)黑鲷幼鱼肝脏脂肪酸合成酶(FAS)活性及基因表达水平均在n-3 HUFA>0.92%时有显著下降(P<0.05);腹腔脂肪激素敏感脂肪酶(HSL)活性及基因表达水平均随饲料中n-3 HUFA的添加呈升高趋势(P<0.05),且高含量n-3 HUFA(0.94%)可使HSL活性增加近一倍。结果表明,饲料中n-3HUFA通过同步调控脂肪合成与分解两个过程影响黑鲷幼鱼脂肪代谢。更多还原

【Abstract】 Six diets containing graded levels(0.79,0.83,0.85,0.88,0.92 and 0.94%) of n-3 highly unsaturated fatty acids(n-3 HUFA) with a constant DHA/EPA,were fed randomly to six groups(Diet 1-6) of fish with triplicate [average weight,(8.08±0.09) g;20 fish/replicate] to determine the effects of dietary n-3 HUFA on growth and lipid metabolism in juvenile black sea bream(Sparus macrocephalus).Results of the 8-week growth trial showed that:(1) Hepotasomatic index(HSI) and intraperitoneal fat(IPF) ratio of juvenile black sea bream decreased with the increase of dietary n-3 HUFA and the values in Diet 5 and 6 were significantly lower than those in other four groups(P<0.05).Adipocyte diameter in IPF was decreased by dietary n-3 HUFA and the significance occurred between Diet 3 and 6.Lipid content in muscle was significantly affected by dietary n-3 HUFA and reached the bottom in Diet 4.No significance was found in whole body proximate composition of juvenile black sea bream.Concerning the fatty acid composition,∑SFA and the main constituent,C16:0 were negatively correlated with dietary n-3 HUFA,while ∑n-3 HUFA content was obviously increased among all the treatments.DHA to EPA ratios(DHA/EPA) in liver,dorsal muscle and IPF were unchanged with the supplementation of dietary n-3 HUFA.Quadratic analysis based on weight gain rate(WGR) indicated that dietary n-3 HUFA requirement for black sea bream was 0.87% DM.(2) Determination of fatty acid synthase(FAS) and hormone-sensitive lipase(HSL) activities showed that FAS activity kept constant in Diet 1 to 4,and then decreased significantly with further increment of dietary n-3 HUFA.HSL activity in IPF increased significantly with the elevation of dietary n-3 HUFA level and increased to almost two times in Diet 6(0.94% n-3HUFA).Gene expression of FAS changed following the similar trend with FAS activity in liver;while expression of HSL in IPF was positively correlated with dietary n-3 HUFA level.In summary,we can deduce that n-3 HUFA regulation in lipid metabolism was realized by affecting the lipogenesis and lipolysis at the same time.更多还原