不同脂肪源对异育银鲫鱼种生长、消化率及体成分的影响

为了探讨不同脂肪源对异育银鲫生长、消化率和体成分的影响,在基础饲料中分别添加4%的鱼油、豆油、猪油、花生油和混合油(鱼油∶豆油∶猪油=3∶4∶3)制成5种等氮试验饲料,饲喂均重为(6.04±0.05)g的异育银鲫60d。结果表明,混合油组的增重率、特定生长率(SGR)显著高于鱼油组和猪油组(P<0.05),但与其他组无显著差异(P>0.05);蛋白质效率(PER)、饲料系数(FCR)各组间均无显著性差异(P>0.05);豆油组的肠体比显著高于鱼油组和猪油组(P<0.05);猪油组的肝体指数(HSI)显著高于鱼油组(P<0.05),猪油组的内脏指数显著高于混合油组(P<0.05);不同脂肪源对肥满度的影响不显著(P>0.05);鱼体肌肉中水分、粗蛋白、粗脂肪、粗灰分和磷各组间差异不显著(P>0.05);猪油组肝脏中粗脂肪含量显著高于鱼油组和花生油组(P<0.05);肝脏中粗蛋白鱼油组和豆油组显著高于猪油组和花生油组(P<0.05);猪油组粗蛋白和粗脂肪的表观消化率显著低于其他各组(P<0.05)。研究结果显示,当豆油和花生油单独添加时,与添加鱼油组表现出相似的生长性能、表观消化率和体成分,而单独添加猪油,鱼体对...     

不同脂肪源对罗氏沼虾生长及体组织常见组分的影响

用5种不同脂肪源组合的饲料(Ⅰ.鱼油0.5%+豆油2.5%;Ⅱ.鱼油0.5%+菜籽油2.5%;Ⅲ.鱼油0.5%+花生油2.5%;Ⅳ.鱼油0.5%+亚麻油2.5%;Ⅴ.豆油1.5%+亚麻油1.5%)投喂体重为(2.22±0.04)g的罗氏沼虾(Macrobrachium rosenbergii)40 d,研究不同脂肪源对其生长及全虾和肌肉中水分、粗蛋白、粗脂肪含量的影响。结果显示:在生长方面,第Ⅴ组的罗氏沼虾增重显著高于Ⅱ组和Ⅲ组(P<0.05),Ⅰ组和Ⅳ组增重也显著大于Ⅱ组(P<0.05)。在体成分方面,Ⅰ组全虾总水分含量最低,显著低于Ⅲ组和Ⅳ组(P<0.05),其他各组间无显著差异(P>0.05);Ⅴ组全虾粗脂肪含量最高,显著高于其他各试验组(P<0.05);Ⅲ组全虾粗蛋白含量显著低于Ⅰ组、Ⅱ组及Ⅴ组(P<0.05);Ⅳ组肌肉总水分含量显著高于其他各组;肌肉粗脂肪和粗蛋白含量各试验组之间差异不显著(P>0.05)。     

不同脂肪源对罗氏沼虾脂肪酸组成的影响

试验旨在探讨饲料中不同脂肪源组合对罗氏沼虾全虾脂肪酸组成的影响.设计5种不同脂肪源组合的饲料(Ⅰ.鱼油0.5％+豆油2.5％;Ⅱ.鱼油0.5％+菜籽油2.5％;Ⅲ.鱼油0.5％+花生油2.5％;Ⅳ.鱼油0.5％+亚麻油2.5％;V.豆油1.5％+亚麻油1.5％),投喂平均体质量为(2.22±0.04)g的罗氏沼虾60 d,采集的全虾样通过气相色谱法分析其脂肪酸相对含量.结果表明:Ⅲ组虾体单不饱和脂肪酸(MUFA)含量最高,达32.58％,显著高于Ⅰ、Ⅳ和V组(P＜0.05).Ⅰ组虾体n-6多不饱和脂肪酸(n-6PUFA)含量最高,为28.62％,并且显著高于其他4组(P＜0.05).Ⅳ组虾体n-3多不饱和脂肪酸(n-3 PUFA)含量最高,为17.17％,并且显著高于Ⅰ和Ⅲ组(P＜0.05).虾体二十碳五烯酸和二十二碳六烯酸含量(EPA+DHA)则是Ⅰ、Ⅱ、Ⅲ组显著高于Ⅳ和V组(P＜0.05).不同脂肪源组合对罗氏沼虾脂肪酸组成有显著影响.     

不同脂肪源对鲤鱼抗氧化功能的影响

在鲤鱼饵料分别添加鱼油、豆油、菜籽油配置成等能等氮的饵料,探讨不同脂肪源对其机体抗氧化功能的影响.结果表明,鲤鱼饵料中分别使用鱼油、豆油、菜籽油对鲤鱼血清中的超氧化物歧化酶和过氧化氢酶活性未产生显著的影响(P>0.05).鱼油组总抗氧化能力和谷胱甘肽过氧化物酶活性显著高于菜籽油组(P<0.05);豆油组总抗氧化能力和谷...     

不同脂肪源饲料对中华绒螯蟹幼蟹生长、消化酶活力和脂肪酸组成的影响

选用初始体重为(2.15±0.10)g的中华绒螯蟹(Eriocheir sinensis)雄性幼蟹,随机分为5组(每组12只幼蟹),饲喂100%鱼油组(简称F1组)、100%豆油组(F2组)、100%亚麻油组(F3组)、50%鱼油+50%豆油组(F4组)、50%鱼油+50%亚麻油组(F5组)不同脂肪源配制的5种等氮等能饲料。实验蟹单个体养殖,实验周期为112 d。结果表明,F5组体重、增重率和特定生长率都显著高于其他饲料组(P0.05),各组的蜕壳间隔和肝胰腺指数没有显著差异(P0.05)。肝胰腺组织消化酶活力测定结果表明,F1组幼蟹肝胰腺的类胰蛋白酶活力显著高于其他各组(P0.05);F3组的胃蛋白酶活力显著高于其他各组(P0.05);F1组、F2组和F4组的脂肪酶活力显著高于其他两组(P0.05);各组的淀粉酶活力差异不显著(P0.05)。脂肪酸测定结果表明,肝胰腺和肌肉中的亚油酸(LOA)(C18:2n-6)、亚麻酸(LNA)(C18:3n-3)、EPA(C20:5n-3)和DHA(C22:6n-3)等主要脂肪酸含量与饲料脂肪酸组成呈正相关关系,F1组的高度不饱和脂肪酸(HUFA)含量显著高于其余各组(P0.05),F2组的LOA含量显著高于其余各组(P0.05),F3组的LNA含量显著高于其余各组(P0.05)。本研究结果表明,以50%的豆油或亚麻油替代鱼油能促进中华绒螯蟹幼蟹的生长,但可能使幼蟹的成活率降低。以豆油或亚麻油替代鱼油会影响幼蟹胰蛋白酶、胃蛋白酶和脂肪酶的活力和肝胰腺、肌肉脂肪酸组成。     

豆油替代鱼油对圆斑星鲽幼鱼生长和肌肉脂肪酸的影响

本实验旨在研究饲料中豆油替代鱼油对圆斑星鲽(Verasper variegatus)幼鱼生长和肌肉脂肪酸组成的影响。用豆油分别替代0、25%、50%和75%的鱼油,配制4组等氮、等脂肪的饲料。选择初始体重为(65.47±1.57)g的圆斑星鲽幼鱼360尾,随机分为4组,每组3个重复,每个重复30尾鱼,养殖56 d。结果显示,(1)随着豆油替代水平的升高,增重率(WGR)呈现降低的趋势(P0.05),饲料系数(FCR)呈现升高的趋势(P0.05),25%替代组的WGR高于鱼油组(P0.05)。(2)豆油替代鱼油对圆斑星鲽肌肉的粗蛋白、粗脂肪、灰分和水分含量无显著性影响(P0.05),对肝体比(HSI)、脏体比(VSI)和肥满度(CF)无显著性影响(P0.05),豆油替代组肝脏的脂肪含量显著高于鱼油组(P0.05)。(3)随着饲料中豆油水平的增加,圆斑星鲽幼鱼肌肉亚油酸(C18:2n-6)和亚麻酸(C18:3n-3)显著升高(P0.05),而二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)则显著降低(P0.05)。研究结果表明,在该实验条件下,饲料中高比例的豆油替代鱼油会降低鱼体的生长性能和肌肉脂肪酸营养品质。     

不同脂肪源对红螯光壳螯虾幼虾生长、消化酶活性及其肌肉生化组成的影响

通过在人工配合饲料中分别添加5%的花生油、猪油、鱼油和豆油作为主要脂肪源,以商业饲料为对照,进行8周饲喂实验,研究不同脂肪源对红螯光壳螯虾(Cherax quadricarinatus)幼虾生长、消化酶活性及其肌肉生化组成的影响。结果显示,不同脂肪源对红螯光壳螯虾幼虾的体长增长率和特定增长率影响不显著(P0.05);但增重率各组间存在显著性差异(P0.05),以豆油组最高,达到2332.93%,花生油组最低,为1839.50%;豆油组肝胰腺指数显著高于其他各组(P0.05),为0.75%。幼虾存活率以豆油组最高(P0.05),达到83.3%,鱼油组较低,仅为56.7%。不同脂肪源饲喂组的肝胰腺胃蛋白酶活力无显著差异(P0.05);脂肪酶活力花生油组显著高于其他实验组(P0.05),为1177.23U/g(prot);淀粉酶活力各组间差异显著(P0.05),由高到低依次为鱼油组、对照组、豆油组、猪油组、花生油组;纤维素酶活力以花生油组较高,为61.14U/(gprot()P0.05)。幼虾腹部肌肉中各种脂肪酸的含量明显受到饲料中脂肪酸种类和含量的影响,饱和脂肪酸含量猪油组显著高于其他组(P0.05);单不饱和脂肪酸以花生油组含量最高,豆油组最低;多不饱和脂肪酸则以豆油组含量最高(P0.05)。在各实验组中,豆油组红螯光壳螯虾幼体具有最高的体质量增长率和存活率,较高的肝胰腺指数和肝胰腺消化酶活力,豆油组幼虾腹部肌肉中多不饱和脂肪酸尤其是亚油酸和亚麻酸含量也较高。因此,以豆油作为主要脂肪源能够满足红螯光壳螯虾幼体的生长需要,获得较好的饲养效果,并降低饲料成本。     

小麦胚芽油替代鱼油对半滑舌鳎幼鱼生长、体成分、血清生化指标及脂肪代谢酶的影响

以初始体重为(3.70±0.01)g的半滑舌鳎(Cynolossus semilaevis Günter)幼鱼为实验对象,研究小麦胚芽油替代鱼油对其生长、体成分、血清生化指标及脂肪代谢酶的影响。以添加7.5%的鱼油组为对照组,用小麦胚芽油分别替代0、20%、40%、60%、80%、100%的鱼油配制成6组等氮等能饲料,在海水循环养殖系统中进行68 d的养殖实验。结果显示:饲料中小麦胚芽油替代鱼油对半滑舌鳎幼鱼存活率无显著影响;随着替代水平的升高,特定生长率和蛋白质效率降低,饲料系数升高。各组间脏体比、肝体比和肥满度均无显著性差异。肝脂肪含量随替代水平的升高而升高,而全鱼脂肪含量降低;80%和100%替代组全鱼水分含量显著高于对照组(P0.05)。随着饲料中小麦胚芽油水平的升高,鱼体组织中亚油酸和亚麻酸含量显著升高(P0.05),EPA和DHA含量显著降低(P0.05)。各组间血清谷丙转氨酶、谷草转氨酶、碱性磷酸酶和溶菌酶活性均无显著性差异(P0.05);80%和100%替代组甘油三酯和总胆固醇含量显著高于对照组(P0.05);血清丙二醛含量呈降低趋势。随着替代水平的升高,肝脂蛋白酯酶、肝酯酶、总酯酶、脂肪酸合成酶以及肠道脂肪酶活性升高。研究表明,在本实验条件下,小麦胚芽油可替代60%的饲料鱼油而不影响半滑舌鳎幼鱼的生长;小麦胚芽油的添加,促进了鱼体脂肪代谢,抑制脂质过氧化作用,但显著改变了鱼体脂肪酸组成。     

豆油和菜油对鲫鱼生长、体成分及血清生化指标的影响

分别以豆油、菜油、混合油(豆油:菜油=1:1)作为脂肪源,制成3种试验饲料,饲养体重为(27.64±2.29)g的鲫57 d,对试验鱼生长、生物学性状、体成分、血清生化指标进行测定,以综合评价豆油和菜油对鲫(Carassius auratus)的影响并进行比较.结果表明,菜油组和豆油组终末体重差异不显著,但均显著高于混合油组(P<0.05);饲料系数、增重率、绝对生长率各组间均无显著差异;内脏指数菜油组和豆油组差异不显著,但均高于混合油组(P<0.05);菜油组的含肉率显著低于混合油组(P<0.05),两者与豆油组差异不显著;菜油组的肝体比显著高于混合油组(P<0.05),两者与豆油组差异不显著;菜油组的肠体比和豆油组差异不显著,但均高于混合油组(P<0.05);肠长比各组间差异均不显著;菜油组的肥满度最高,混合油组最低,且组间差异显著(P<0.05);豆油组肌肉粗蛋白含量显著高于菜油组(P<0.05),与混合油组间差异不显著;混合油组肌肉粗灰分含量显著高于菜油组(P<0.05),与豆油组含差异显著;鱼体肌肉水分、粗脂肪、肝胰脏脂肪含量及血清生化指标各组间差异不显著.研究结果显示,豆油、菜油单独作为脂肪源对鲫生长、血清牛化性状的影响没有显著差异,但豆油能够改善鲫的体形,提高鲫的肌肉粗蛋白含量,而2种油脂混合使用则抑制鲫的生长,其原因可能与鲫的消化道发育受到抑制有关.建议生产中使用豆油为鲫的脂肪源,并避免同时使用豆油和菜油.     

鱼油对幼鼠血清总脂、总胆固醇及组织脂肪酸组成的影响

本实验是选用雌雄两性的幼鼠,按随机区组法分成三组,分别在基础饲料中添加豆油、鱼油和鱼油浓缩物。喂养4周后,发现喂鱼油和鱼油浓缩物的两组幼鼠血清总脂和总胆固醇含量低于喂豆油组的(P<0.05)。脂肪酸分析表明:喂鱼油及喂鱼油浓缩物组幼鼠的脑、肝、脾和肾组织的二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)明显比喂豆油组的高。相反,喂豆油组的花生四烯酸和二十二碳四烯酸却比喂鱼油及喂鱼油浓缩物组的高。三组的体重增长率、血清总蛋白、碱性磷酸酶及脏体比都没有显著差异(P>0.05)。     

Growth,antioxidant capacity,intestine histology and lipid metabolism of juvenile red claw crayfish,Cherax quadricarinatus,fed different lipid sources

Five dietary lipid sources (fish oil, soybean oil, palm oil, rapeseed oil and linseed oil) were evaluated in juvenile red claw crayfish, Cherax quadricarinatus, based on the response of growth, antioxidant capacity, intestine histology, whole‐body composition, fatty acid nutrition and lipid metabolism. Crayfish were fed in quadruplicate net cages for 8 weeks. Crayfish fed diets with fish oil, soybean oil and linseed oil obtained significantly higher weight gain and specific growth rate than those fed the other two diets. Survival, condition factor and hepatosomatic index were not significantly affected by lipid sources. Lipid sources also do not affect the whole‐body composition of crayfish. Serum SOD, T‐AOC and GSH‐PX activities of crayfish fed the palm oil and rapeseed oil diets had a significantly lower value than those fed other diets. The minimum concentrations of MDA have been observed in crayfish fed the soybean oil diet. The activity of ACC in the hepatopancreas of crayfish fed the linseed oil diet showed the highest value, and the CPT‐1 activity was not significantly affected by different lipid sources. Crayfish fed the soybean oil diet showed significantly higher TC and TG contents in hepatopancreas than those fed other diets. Crayfish fed linseed oil diet had a significantly higher percentage of EPA, C18:3n?3 and Σn?3 PUFA in muscle than those fed other treatments. Most of the fatty acid compositions in the hepatopancreas had a close correlation to fatty acid compositions in diets. All findings in this study indicate that soybean oil is the advantageous lipid source for juvenile C. quadricarinatus which can reflect in satisfactory growth performance, antioxidant capacity and fatty acid nutrition of edible tissues.     

Effect of soybean meal,raffinose and stachyose on the growth,body composition,intestinal morphology and intestinal microflora of juvenile allogynogenetic silver crucian carp (Carassius auratus gibelio♀×Cyprinus carpio♂)

The study was conducted to investigate the effects of soybean meal (SBM), raffinose and stachyose on juvenile crucian carp (Carassius auratus gibelio♀ × Cyprinus carpio♂). The experimental diets consisted of one control diet based on fish meal (FM), one diet containing 300 g kg^?1 SBM and four FM‐based diets with the addition of either 6.7 g kg^?1 raffinose (Raf), 33.9 g kg^?1 stachyose (Sta), a combination of raffinose and stachyose (Raf?Sta) and finally a Raf?Sta diet supplemented with 2.5 g kg^?1 saponins (Raf?Sta?Sap). After 3 weeks of feeding, the relative gut lengths of SBM‐fed fish and the fish fed stachyose‐containing diets were shorter than those of the FM‐fed fish; further, more SBM‐fed fish showed fissures on the tips of the intestinal folds. After 8 weeks of feeding, the growth of SBM‐fed fish was significantly lower than that of FM‐fed fish (P<0.05). The fish fed Raf?Sta?Sap had a low relative gut length (P<0.05). In comparison with the other fish, the SBM‐fed fish had a higher number of large‐sized homogeneous vacuoles in the cytoplasm of epithelial cells and shorter microvilli. No significant difference was observed in body composition or intestinal microflora. The results indicated that raffinose and stachyose played no or only minor roles in the development of soybean‐induced growth reduction.     

Effects of different dietary lipid sources in the diet for Pangasius hypophthalmus (Sauvage, 1878) juvenile on growth performance,nutrient utilization,body indices and muscle and liver fatty acid composition

Four isonitrogenous (300 g kg^?1 crude protein), isoenergetic (21 kJ g^?1) experimental diets were formulated to contain fish oil (FO), soybean oil (SBO), crude palm oil (CPO) and linseed oil (LO), respectively, as lipid sources each at inclusion level of 120 g kg^?1 and fed to triplicate groups of 15 juvenile iridescent shark, Pangasius hypophthalmus (Sauvage, 1878) (mean weight 10.00 ± 0.70 g) to apparent satiation twice daily for 12 weeks. The results showed that survival of fish was consistently over 95% for all treatments whereas growth performance in the SBO and CPO treatments was similar and significantly (P < 0.05) higher than for fish fed the LO diet. However, fish fed all vegetable oil‐based diets performed better than those fed the FO diet. Muscle and liver fatty acid composition for all treatments generally reflected the composition in the diet and the ratio of n‐3/n‐6 was found to play an important role in P. hypophthalmus, suggesting that excessive amounts of n‐3 fatty acids reduce the overall growth performance. Results of this study thus suggests that P. hypophthalmus fed diets containing vegetable oils (especially CPO and SBO) produce better growth than those fed FO diet without showing any signs of nutrient deficiency.     

Effects of different dietary lipid sources in the diet for Pangasius nasutus (Bleeker, 1863) juveniles on growth performance,feed efficiency,body indices and muscle and liver fatty acid compositions

Four isonitrogenous (300 g kg^?1 crude protein), isoenergetic (21 kJ g^?1) experimental diets were formulated to contain fish oil (FO), soybean oil (SBO), crude palm oil (CPO) and linseed oil (LO), respectively, as the lipid sources, added at 120 g kg^?1 of crude lipid each. The diets were fed by hand to triplicate groups of Pangasius nasutus (Bleeker, 1863) juveniles (mean weight 10.66 ± 0.04 g), to apparent satiation twice daily for 12 weeks. Fish survival rate was 100% among all the treatments. Growth performance (DGR) was similar among fish fed the SBO, CPO and LO diets, but was significantly (P < 0.05) higher in the CPO compared to fish fed the control (FO) diet. Fish fed SBO and CPO diets also recorded significantly (P < 0.05) higher intraperitoneal fat compared to fish fed the control, whereas fish fed the LO diet did not significantly differ from the other treatments. Muscle and liver fatty acid profile of fish from all the treatments generally mirrored the composition of the diets fed and the major fatty acids recorded were 18:3n‐3 and 18:2n‐6 in the tissues of fish fed the LO and SBO treatments, respectively. Results of this study suggests that P. nasutus fed diets containing vegetable oils (especially CPO and SBO) produce better growth performance, without compromising fish survival and feed efficiency compared with those fed a diet containing only FO.     

Effects of different dietary lipid sources on growth performance,antioxidant enzyme activities and biochemical composition of juvenile swimming crab,Portunus trituberculatus

An 8‐week feeding trial was conducted to evaluate the effects of dietary lipid sources on growth performance, antioxidant enzyme activities and biochemical composition of juvenile swimming crab Portunus trituberculatus of initial weight 2.34 ± 0.08 g. Four different diets were formulated to contain fish oil (FO), soybean oil (SO), linseed oil (LO) or palm oil (PO). The highest final body weight, weight gain, specific growth rate and molting frequency were observed in crabs fed the FO diet. Crabs fed the SO diet showed higher glutathione peroxidase, superoxide dismutase (SOD) and catalase (CAT) activities in both serum and hepatopancreas than those fed the FO diet. The lowest malondialdehyde concentration in hepatopancreas and serum were occurred at crabs fed the SO diet. Crabs fed the LO diet had significantly higher SOD and CAT activities in hepatopancreas compared with those fed the FO diet. Crabs fed the PO diet had the highest activities of fatty acid synthase and carnitine palmitoyltransferase 1 activities in hepatopancreas among all treatments. Fatty acid compositions both in hepatopancreas and muscle reflected those of diets. Overall, these findings demonstrated that physiological–biochemical characteristics and lipid metabolism were significantly regulated by different dietary lipid sources. Moreover, dietary SO and LO supplementation could improve antioxidant ability.     

Influences of dietary fatty acid profile on growth, body composition and blood chemistry in juvenile fat cod (Hexagrammos otakii Jordan et Starks)

This study was conducted to investigate the influence of dietary lipid source and n‐3 highly unsaturated fatty acids (n‐3 HUFA) level on growth, body composition and blood chemistry of juvenile fat cod. Triplicate groups of fish (13.2 ± 0.54 g) were fed the diets containing different n‐3 HUFA levels (0–30 g kg^?1) adjusted by either lauric acid or different proportions of corn oil, linseed oil and squid liver oil at 100 g kg^?1 of total lipid level. Survival was not affected by dietary fatty acids composition. Weight gain, feed efficiency and protein efficiency ratio (PER) of fish fed the diets containing squid liver oil were significantly (P < 0.05) higher than those fed the diets containing lauric acid, corn oil or linseed oil as the sole lipid source. Weight gain, feed efficiency and PER of fish increased with increasing dietary n‐3 HUFA level up to 12–16 g kg^?1, but the values decreased in fish fed the diet containing 30 g kg^?1 n‐3 HUFA. The result of second‐order polynomial regression showed that the maximum weight gain and feed efficiency could be attained at 17 g kg^?1 n‐3 HUFA. Plasma protein, glucose and cholesterol contents were not affected by dietary fatty acids composition. However, plasma triglyceride content in fish fed the diet containing lauric acid as the sole lipid source was significantly (P < 0.05) lower than that of fish fed the other diets. Lipid content of fish fed the diets containing each of lauric acid or corn oil was lower than that of fish fed the diets containing linseed oil or squid liver oil only. Fatty acid composition of polar and neutral lipid fractions in the whole body of fat cod fed the diets containing various levels of n‐3 HUFA were reflected by dietary fatty acids compositions. The contents of n‐3 HUFA in polar and neutral lipids of fish increased with an increase in dietary n‐3 HUFA level. These results indicate that dietary n‐3 HUFA are essential and the diet containing 12–17 g kg^?1 n‐3 HUFA is optimal for growth and efficient feed utilization of juvenile fat cod, however, excessive n‐3 HUFA supplement may impair the growth of fish.     

Regulation of growth, fatty acid composition and delta 6 desaturase expression by dietary lipids in gilthead seabream larvae (Sparus aurata)

The Δ6 and Δ5 desaturases and elongases show only very limited activity in marine fish, and little is known of the possibility of enhancing Δ6 desaturase gene expression in these fish. The use of plant oils in marine fish diets is limited by their lack of n−3 highly unsaturated fatty acids (HUFA) despite an abundant content of the 18C fatty acid precursor linoleic and α-linolenic acids. The objective of the present study was to determine the ability of larval gilthead seabream to utilize vegetable oils and assess the nutritional regulation of Δ6 desaturase gene expression. Seventeen-day-old gilthead seabream larvae were fed during a 17-day period with one of four different microdiets formulated with either sardine fish oil (FO), soybean, rapeseed or linseed oils, respectively, or a fifth diet containing defatted squid meal and linseed oil. Good larval survival and growth, both in terms of total length and body weight, were obtained by feeding the larvae either rapeseed, soybean or linseed oils. The presence of vegetable oils in the diet increased the levels of 20:2n−9 and 20:2n−6, 18:2n−9, 18:3n−6, 20:3n−6 and 20:4n−6, in larvae fed rapeseed and soybean oils in comparison to those fed FO. In addition, a sixfold increase in the relative expression of Δ6 desaturase-like gene was found in larvae fed rapeseed and soybean oils, denoting the nutritional regulation of desaturase activity through its gene expression in this fish species. However, feeding linseed oil did not increase the expression of the Δ6 desaturase gene to such a high extent.     

Growth and immune response of Chinese mitten crab (Eriocheir sinensis) fed diets containing different lipid sources

A 10‐week feeding trial was conducted to evaluate the effects of dietary lipid sources on the growth and immune responses of Chinese mitten crab Eriocheir sinensis. Six isonitrogenous and isoenergetic diets were formulated with fish oil (FO), linseed oil (LO), soybean oil (SO), rapeseed oil (RO), coconut oil (CO) and beef tallow (BT) as the sources of lipid with five replicates each. Thirty crabs (2.35 ± 0.14 g) were stocked into each tank and fed twice daily. Weight gain and specific growth rate of crab fed the FO diet were significantly lower than those fed other diets (P < 0.05), except for crabs fed LO diet (P < 0.05). Crab fed the SO diet weighed more than those fed FO diets (P < 0.05). Serum superoxide dismutase and malondialdehyde of crab fed the FO diet were significantly higher than in other groups (P < 0.05). Crab fed the FO diet had the highest activities of serum phenoloxidase, acid phosphatase, alkaline phosphatase and lysozyme (P < 0.05). The fatty acid composition in the liver of crab reflected the change in test diets. Our results indicate that the use of dietary vegetable or animal oils can achieve similar growth performance to the use of dietary FO in Chinese mitten crab, but non‐FOs may impair crab immunity. Soybean oil is recommended as a suitable replacer for FO in Chinese mitten crab diet.     

Effects of total replacement of fish oil by pork lard or rapeseed oil and recovery by a fish oil finishing diet on growth,health and fish quality of gibel carp (Carassius auratus gibelio)

An 84‐day growth trial was designed to investigate effects of dietary replacements fish oil with pork lard (PL) or rapeseed oil (RO) on growth and quality of gibel carp (Carassius auratus gibelio var. CAS III) (initial body weight: 158.2 ± 0.2 g), and responses of the fish refed fish oil (FO) diet. Three isonitrogenous (crude protein: 30%) and isolipid (crude lipid: 10%) diets were formulated containing 7.73% FO, PL or RO. Five experimental treatments including FO group (FO), PL group (PL), RO group (RO), group fed PL for 42 days and refed FO for 42 days (PL+rFO), RO and refed FO group (RO+rFO) was tested. At the end of first 42 days, the fish fed PL and RO had higher mortality than that of the control (P > 0.05). At the end of whole experiment, fish fed PL and RO showed higher plasma cortisol than FO fish (P < 0.05). RO+rFO fish showed higher lysozyme activity than RO fish (P < 0.05). Fish growth and feed utilization, composition of whole body and muscle, free amino acids, texture, off‐flavour substances or sensory attributes were not affected by dietary treatments (P > 0.05). PL and RO diet decreased muscle EPA, DHA and n‐3/n‐6 ratio (P < 0.05), while FO‐refeeding had recovery effect. It can be concluded that the replacement of FO by PL and RO does not affect the growth, feed utilization or fish tasting quality in gibel carp. Fish muscle fatty acids modified by dietary PL and RO can be recovered by refeeding with FO diet.     

Effects of Different Dietary Lipid Sources on the Survival, Growth, and Fatty Acid Composition of South American Catfish, Pseudoplatystoma fasciatum, Surubim, Juveniles

The present study examines the effect of four semi‐purified diets (casein–gelatin based) where the source of fatty acids was free (esterified) oleic acid and linoleic acid (LA) (LOA diet), linseed and olive oil (predominantly LA and linolenic acid) (LO diet), cod liver oil (rich in highly unsaturated fatty acids) (CLO diet), and soybean lecithin (phospholipids; mostly LA) (LE diet) on the growth of juvenile South American catfish (surubim, Pseudoplatystoma fasciatum, Pimelodidae) (0.98 ± 0.04 g individual weight). Fish were fed at a restricted–readjusted feeding rate for 8 wk. At the end of the experiment, LE‐diet‐fed fish grew significantly larger than those of the other three groups (P < 0.05). Considerable cannibalism was observed in all the treatments. It is suggested that the quantitative growth performance may possibly change under other conditions, with less or no cannibalism. Survival did not differ significantly among the fish fed four different diets. Muscle and liver lipid contents did not vary among dietary treatments (P > 0.05), but whole‐body lipid concentrations were affected by dietary treatments. Fish fed LE diet contained significantly lower lipid level than those fed three other diets (P < 0.05). Muscle and liver fatty acid profiles reflected dietary fatty acid composition. Arachidonic acid level was significantly higher in muscle and liver of fish fed LOA and LE diets than in those fed LO and CLO diets. The results suggest that the efficiency of elongation and desaturation of 18C fatty acids depends on the dietary lipid source, and South American catfish has considerable capacity to transform linoleate to arachidonate.