不同脂肪水平下添加胆汁酸对大菱鲆(Scophthalmus maximus)幼鱼生长、体组成和脂肪代谢的影响

EFFECTS OF DIETARY BILE ACIDS ON GROWTH,BODY COMPOSITION AND LIPID METABOLISM OF JUVENILE TURBOT(SCOPHTHALMUS MAXIMUS) AT DIFFERENT LIPID LEVELS

在10%和18%两个脂肪水平下,分别添加0%、1.5%的胆汁酸,配制成四种等氮饲料,投喂初始平均体重为(45.78±0.11)g的大菱鲆(Scophthalmus maximus)幼鱼8周,研究两个脂肪水平下添加胆汁酸对大菱鲆幼鱼生长、体组成和脂肪代谢的影响。结果表明:饲料脂肪水平升高或添加胆汁酸均能显著提高大菱鲆幼鱼增重率、特定生长率、蛋白质效率,降低饵料系数(P<0.05);相同脂肪水平下,添加胆汁酸显著提高了实验鱼的生长,降低了肝体比(P<0.05)。随着饲料脂肪水平的升高,组织中粗脂肪含量呈上升的趋势;而添加胆汁酸降低了组织中脂肪的蓄积,但全鱼与肌肉中水分、粗蛋白含量主要受饲料中胆汁酸水平的影响(P<0.05)。胆汁酸能显著降低大菱鲆幼鱼肌肉PUFA含量(P<0.05),增加SFA、MUFA含量。饲料添加胆汁酸能降低实验鱼血清甘油三酯、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇含量及谷草转氨酶、谷丙转氨酶活性(P<0.05),但饲料脂肪水平对血液生化指标的影响呈相反趋势。饲料脂肪水平的升高或添加胆汁酸均能提高实验鱼肝脏脂蛋白脂酶、肝脂酶、总脂酶和肠道脂肪酶活性(P<0.05),且胆汁酸和脂肪二者之间的交互作用对脂肪代谢有显著影响(P<0.05)。综上所述,在2个脂肪水平下添加胆汁酸均能促进大菱鲆幼鱼的生长,提高饲料利用状况,促进脂肪消化吸收,降低组织中粗脂肪含量。

The objective of this study was to investigate the effects of dietary bile acids on growth performance,body composition and lipid metabolism of juvenile turbot(Scophthalmus maximus) at different lipid levels.The fish with initial average weight of(45.78±0.11)g were fed four isonitrogenous diets at lipid levels of 10% and 18% supplemented with 0% and 1.5% bile acids for 8 weeks,respectively.With dietary increasing lipid levels or bile acids supplementation,growth rate,specific growth rate and protein efficiency were significantly increased(P<0.05); however,feed conversion ratio was reduced(P<0.05).Adding bile acids significantly promoted fish growth(P<0.05),while hepatosomatic index decreased at the same lipid level(P<0.05).Crude lipid contents of tissues showed an increasing trend as lipid levels increased,while adding bile acids reduced the accumulation of crude lipid contents in tissues.Moisture and crude protein contents of whole fish and dorsal muscle were mainly affected by diets supplemented with bile acids(P<0.05).Addition of bile acids significantly reduced PUFA contents of dorsal muscle(P<0.05),and increased SFA and MUFA contents.For fish fed diets with 10% and 18% lipid levels,addition of bile acids significantly reduced contents of serum triglyceride,total cholesterol,high-density lipoprotein cholesterol,low-density lipoprotein cholesterol,as well as the activities of ALT and AST(P<0.05).However,the serum biochemical indices showed an opposite trend with the increasing dietary lipid levels.In terms of lipid metabolism enzymes,increasing the dietary lipid levels or bile acids supplementation significantly elevated activities of lipoprotein lipase,hepatic lipase,total lipase and intestinal lipase(P<0.05); moreover,statistical interaction of dietary lipid and bile acids was found on activities of lipid metabolism enzymes(P<0.05).The results show that adding bile acids can not only promote growth performance and feed utilization,but also reduce the accumulation of body fat and thereby protect liver functions of juvenile turbot at two different lipid levels.