饲料中添加龙须菜对草鱼生长性能、血清生化指标及肌肉脂肪酸组成的影响

为考察饲料中添加龙须菜对草鱼生长性能、血清生化指标及肌肉脂肪酸组成的影响,试验共配制了6种龙须菜添加比例分别为0(对照组)、1%、2%、3%、4%和5%的等氮等脂饲料,投喂平均体重为(15.94±0.10)g的草鱼8周。每种饲料投喂4个水箱(重复),每箱30尾鱼。结果显示:1)饲料中不同添加比例龙须菜对草鱼的增重率(WGR)、特定生长率(SGR)、存活率(SR)及饲料效率(FE)没有显著影响(P0.05)。2)各试验组的肝体指数(HSI)均高于对照组,对照组与除5%添加组外的其他试验组的差异均达到显著水平(P0.05)。3)全鱼、肝脏及肌肉的粗蛋白质含量各组间皆无显著差异(P0.05),而饲料中不同添加比例龙须菜对全鱼粗灰分与粗脂肪、肝脏粗脂肪及肌肉水分含量有显著影响(P0.05)。4)血清总蛋白(TP)、总胆固醇(TCHO)、甘油三酯(TG)以及低密度脂蛋白(LDL)含量以5%添加组最低,显著低于对照组(P0.05),其他试验组与对照组没有显著差异(P0.05)。5)饲料中龙须菜添加比例影响了草鱼肌肉脂肪酸的组成,除C14∶1、C20∶0、C20∶2外,其他肌肉脂肪酸的含量均受到饲料中龙须菜的添加比例的显著影响(P0.05),其中肌肉多不饱和脂肪酸(PUFA)含量及n-3/n-6 PUFA均在3%添加组获得最高值。1%、2%、3%、4%和5%添加组肌肉C20∶5(EPA)、C22∶5(DPA)、C22∶6(DHA)以及EPA+DHA的含量都显著高于对照组(P0.05)。由此得出,饲料中添加一定比例的龙须菜对草鱼的生长性能没有显著影响,但能降低血脂含量,影响草鱼肌肉脂肪酸的组成,并能提高功能性脂肪酸DHA、EPA及PUFA的含量;饲料中添加3%的龙须菜能更好地增加肌肉功能性脂肪酸含量,而添加5%的龙须菜则草鱼生长相对较好,降低血脂效果更加明显。

Effects of Dietary Gracilaria lemaneiformis on Growth Performance,Serum Biochemical Indices and Muscle Fatty Acid Composition of Grass Carp (Ctenopharyngodon idellus)

In order to evaluate the effects of dietary Gracilaria lemaneiformis on growth performance, serum biochemical indices and muscle fatty acid composition of grass carp ( Ctenopharyngodon idellus) , juvenile fish at the average body weight of (15.94±0.10) g were fed six isonitrogenous and isolipid diets containing graded levels of Gracilaria lemaneiformis [ 0 ( control group ) , 1%, 2%, 3%, 4% and 5%, respectively ] for 8 weeks. Each diet fed four water tanks and each tank had 30 fish. The results showed as follows:1) there were no significant differences in weight gain rate ( WGR) , specific growth ratio ( SGR) , survival rate ( SR) and feed efficiency ( FE) of fish fed diets supplemented with different proportions of Gracilaria lemaneiformis ( P>0.05) . 2) Hepato-somatic index ( HSI) of fish in experimental groups was higher than that in control group, and the differences were significant except 5% supplementation group ( P<0.05) . 3) Crude protein content in whole body, liver and muscle was not significantly affected by diets supplemented with different levels of Gracilaria lemaneiformis (P>0.05), however, there were significant differences in the contents of ash and crude lipid in whole body, crude lipid in liver and moisture in muscle ( P<0.05) . 4) Total protein ( TP) , total cholesterol ( TCHO) , triglycerides ( TG) and low density lipoprotein ( LDL) contents in serum in 5% supple-mentation group had the lowest values, and significantly higher than those in control group ( P<0.05) , but no significant differences were found between control group and other experimental groups (P>0.05). 5) Fatty acid composition in muscle of grass carp was affected by diets with different proportions of Gracilaria lemane-iformis. Diets supplemented with different proportions of Gracilaria lemaneiformis could significantly affect the contents of fatty acids except C14∶1, C20∶0 and C20∶2 in muscle ( P<0.05) , and the highest values of poly-unsaturated fatty acids ( PUFA) content and n-3/n-6 PUFA were found in 3% supplementation group. The con-tents of C20∶5 ( EPA) , C22∶5 ( DPA) , C22∶6 ( DHA) and EPA+DHA in muscle in 1%, 2%, 3%, 4% and 5% supplementation groups were significantly higher than those in control group ( P<0.05) . The present results indicate that diets supplemented with a certain proportion of Gracilaria lemaneiformis have no significant effect on the growth of grass carp, but can reduce the blood lipid contents. It can also influence the fatty acid compo-sition in muscle, improve the functional fatty acid contents, such as DHA and EPA, and increase the content of PUFA. The fish fed with 3% Gracilaria lemaneiformis can better increase the functional fatty acid contents was, and the fish fed with 5% Gracilaria lemaneiformis have a relatively better growth performance as well as an obviously lower blood lipid.