抗生素药饵对中华鳖稚鳖摄食和生长的影响

将红霉素（ＥＭ）、氯霉素（ＣＰ）和土霉素（ＯＴＣ）分别按５０、１５０和３００μｇ／ｇ用量添加在配合饲料中投喂中华鳖稚鳖，结果表明，饲喂拌有ＥＭ、ＣＰ和ＯＴＣ的药饲对供试中华鳖稚鳖的摄食量和增生率没有显著影响，而相同抗生素不同添加剂量对中华鳖稚鳖的增生率有显著影响。     

亚麻籽油替代鱼油对大菱鲆幼鱼生长、脂肪酸组成及脂肪沉积的影响

为研究亚麻籽油替代不同鱼油水平对大菱鲆幼鱼[初始体质量为(5.89±0.02)g]生长、脂肪酸组成以及肝脏和肌肉脂肪沉积的影响,以亚麻籽油分别替代0、33.3%、66.7%和100%鱼油,配制4种等氮等脂饲料。每组饲料随机投喂3组实验鱼,饱食投喂,养殖周期为92 d。结果发现,饲料亚麻籽油水平并未显著影响大菱鲆幼鱼存活率(SR)和特定生长率(SGR),但显著影响其摄食率(FI)、饲料效率(FE)和表观净蛋白利用率(ANPU)。随饲料亚麻籽油水平升高,FI显著升高,而FE和ANPU显著下降,且其均在100%亚麻籽油组分别达到最大值或最小值。饲料亚麻籽油水平并未显著影响大菱鲆饲料脂肪表观消化率、肝体比和肌肉脂肪含量。当饲料中亚麻籽油替代100%鱼油,鱼体肝脏脂肪含量显著高于全鱼油组。肝脏和肌肉脂肪酸组成与饲料脂肪酸组成相似。相对于全鱼油组,亚麻籽油替代组肌肉和肝脏中亚油酸和亚麻酸显著升高,而EPA和DHA含量显著下降。研究表明,大菱鲆饲料中亚麻籽油替代水平应低于66.7%,且大菱鲆饲料中n-3长链多不饱和脂肪酸含量需大于0.8%。     

不同脂肪源日粮补充维生素E对罗氏沼虾生长、免疫及肉品质的影响

本研究旨在完善罗氏沼虾（）饲料配方，降低罗氏沼虾饲料成本。研究采用3×2双因素设计，配制6组饲料，分别包含鱼油（fish oil，FO）、豆油（soybean oil，SO）、菜籽油（rapeseed oil，RO）三种脂肪源；200 mg/kg（200VE）和600 mg/kg（600VE）两个维生素E（VE）水平。养殖实验在温室水泥池中进行，每个处理3个重复，养殖期8周，每天定点定量投喂3次。结果显示，相对于FO组，SO和RO组增重率、特定生长率显著升高，饵料系数显著下降（>0.05）。对于血淋巴抗氧化指标，在相同VE水平下，FO组血淋巴总抗氧化能力（T-AOC）和超氧化物歧化酶（SOD）活性均显著低于SO和RO组，谷胱甘肽过氧化物酶（GPX）活性均显著高于SO和RO组（<0.05）。在相同脂肪源下，600VE可显著提高FO组T-AOC活性，RO组GPX活性以及SO和RO组SOD活性（>0.05）。对于血淋巴生理生化指标，谷草转氨酶（AST）、总蛋白（TP）、白蛋白（ALB）和甘油三酯（TC）受日粮影响显著（<0.05）。此外，日粮脂肪源和VE水平对肉质也有显著影响。其中，SO组肌肉鲜度和滋味强度较高；RO组鱼腥味较低；FO组肌肉亮度较高，气味强度较低。在200 mg/kg VE水平下，FO组肌肉硬度、胶黏性、耐咀性、黏性和回复性显著高于植物油组（<0.05），而对肌肉蒸煮损失和滴水损失无显著影响（>0.05）。上述结果表明，相对于鱼油，豆油和菜籽油等植物油是罗氏沼虾更优质的脂肪源，VE在以鱼油为单一脂肪源的饲料中有一定的促生长和缓解应激的作用，且脂肪源和VE均显著影响肌肉品质。本研究结果将为降低鱼油在罗氏沼虾饲料中的使用提供数据支持。     

不同蛋氨酸剂型对中华鳖生长性能和肝脏基因表达的影响

为了研究在低鱼粉含量饲料中分别添加不同蛋氨酸剂型对中华鳖生长性能、消化酶活性、肝脏相关基因表达的影响,以初始体质量为(3.48±0.03)g的中华鳖(Pelodiscus sinensis)稚鳖为试验对象,配制5组饲料,其中正对照组(T1)饲料蛋白的质量分数为46%,添加鱼粉的质量分数为46%,负对照组(T2)饲料蛋白质量分数为43%,添加鱼粉的质量分数为23%,在T2饲料的基础上分别添加0.1%DL-蛋氨酸(T3)、0.2%包膜蛋氨酸(T4)和0.125%羟基蛋氨酸钙(T5),开展持续8周的养殖试验。结果显示,T2组的特定生长率显著低于T1组(P0.05),摄食添加不同蛋氨酸剂型饲料的试验组,中华鳖的特定生长率均显著高于T2组,其中T3、T5组与T1组无显著差异(P0.05)。添加蛋氨酸可显著提高试验鳖的胃淀粉酶活性(P0.05),T3和T5组的胃蛋白酶活性以及T3组的脂肪酶活性相对T2组均显著提高(P0.05)。添加蛋氨酸显著提高了中华鳖肝脏GHR和IGF-I基因mRNA的表达量(P0.05),T3和T5组的IGF-ⅡmRNA相对表达量也显著高于T2组(P0.05)。T5组的HSP70 mRNA相对表达量显著高于T2和T4组(P0.05),T2组的HSP90 mRNA相对表达量显著低于除T4组以外的其它各组(P0.05)。结果表明,在低鱼粉含量的饲料中补充不同剂型蛋氨酸对中华鳖幼鳖的生长性能有不同程度的促进作用,其中补充0.1%的DL-蛋氨酸和0.125%的羟基蛋氨酸钙可达到T1组的养殖效果。     

牛磺酸缓解脂质氧化日粮对黄河鲤生长性能和肠道健康的负面影响

为了探究牛磺酸对脂质氧化饲料饲喂下黄河鲤生长性能和肠道健康的影响,实验先用等量的氧化鱼油（记为OFO）替换基础日粮（记为FO）中的新鲜鱼油,接着将不同含量（0.4%、0.8% 和1.2%）的牛磺酸分别加入OFO组饲料中（分别记为T0.4、T0.8和T1.2）,对初始体重为（8.74±0.01）g的黄河鲤进行为期10周的养殖实验。结果显示,与FO组相比,OFO组的终末体质量、增重率、特定增长率和饲料效率均显著降低。上述所有指标在T0.4、T0.8和T1.2组中均显著高于OFO组。另外,OFO组中肝胰脏抗氧化酶的mRNA表达水平显著低于FO组,而牛磺酸添加组中肝胰脏和肠道的抗氧化酶mRNA表达均有不同程度的上调。与FO组相比,OFO组中的肠道消化酶活性,肠绒毛高度、肠绒毛宽度和肌层厚度均显著降低,而在牛磺酸添加组中均得到提高。同样的,OFO组中肠道微生物组成的丰富度和多样性显著降低,条件致病菌丰度明显升高,而有益菌的丰度却有所下降,这些不良现象在牛磺酸组中均得到明显改善。研究表明,牛磺酸可缓解脂质氧化饲料对黄河鲤造成的生长性能抑制、肠道组织结构破坏、消化功能下降及肠道菌群紊乱等不良影响。结合本研究结果,在氧化脂质饲料中牛磺酸的建议添加剂量为0.4~0.8%。本研究为进一步探索牛磺酸对鱼类肠道的生物学功能奠定理论基础。     

蚕蛹油等7种油脂对吉富罗非鱼生长、体组成及脂质代谢影响的比较

为研究蚕蛹油在吉富罗非鱼饲料中应用的可行性,在饲料中分别添加5.0%的蚕蛹油(SPO)、海水鱼油(MFO)、罗非鱼油(TO)、猪油(PL)、鸡油(CO)、亚麻籽油(LO)和大豆油(SO),配制成7种等氮等脂实验饲料,饲喂初始均重为(47.51±0.52)g的实验鱼。每个处理设置3个重复,每个重复放鱼20尾,进行56 d的养殖实验。结果显示,罗非鱼终末均重、增重率和特定生长率均为LO和SO组显著高于SPO和MFO组,与TO、PL和CO组差异不显著。饲料系数SPO组显著高于除MFO组外的其余各组,而蛋白质效率与之相反。摄食量SPO组最低,SO组最高。TO组罗非鱼脏体比、体长/体高和腹脂率均为最低,而肥满度最高。肝体比PL组显著高于除LO组外的其他各组。腹脂率MFO组显著高于除CO组外的其余各组。同其他组相比,SPO可降低罗非鱼全鱼、组织粗脂肪及血清甘油三酯(TG)、葡萄糖和丙二醛的含量;MFO可降低全鱼粗脂肪的含量和提高肝脏乙酰辅酶A羧化酶(ACC)的活性;PL组罗非鱼血清TG和总胆固醇(TC)含量均较低,而肝脏肉碱脂酰转移酶-I和ACC活性均较高;CO组血清TG、TC、低密度脂蛋白胆固醇(LDL-C)含量和谷草转氨酶活性均为最高;LO和SO可显著提高罗非鱼对饲料脂肪的沉积率和全鱼、肌肉粗脂肪的含量,SO还可显著提高血清高密度脂蛋白胆固醇(HDL-C)和降低LDL-C、TC的含量;SPO、LO和SO可分别显著提高罗非鱼肌肉中高不饱和脂肪酸、α-亚麻酸和亚油酸的含量。研究表明,SPO作为吉富罗非鱼饲料的单一脂肪源,虽会影响其生长性能,但具有降体脂、血脂和血糖,保护鱼体健康和优化肌肉脂肪酸组成等优点。     

复方中草药制剂对中华鳖生长、体组成及血清指标的影响

将初始体质量为(3.28±0.15)g的中华鳖稚鳖分为4组,每组设3个重复,分别投喂添加0%、0.5%、1%、2%复方中草药的试验饲料60d,研究复方中草药对中华鳖生长、体成分和某些血清指标的影响。试验结果显示,各组间成活率无显著差异(P0.05)。1%添加组中华鳖的体质量增加率最高,显著高于对照组(P0.05),与0.5%和2%添加组无显著差异(P0.05)。1%添加组中华鳖的肝体比最低,2%添加组中华鳖的脏体比最低。随着中草药添加量的升高,中华鳖的体蛋白含量显著升高(P0.05),灰分含量显著降低(P0.05)。复方中草药添加量对中华鳖体水分和粗脂肪无显著影响(P0.05)。1%与2%复方中草药组鳖体总氨基酸、必需氨基酸以及鲜味氨基酸高于对照组。中华鳖血清谷草转氨酶、谷丙转氨酶含量随中草药含量升高而显著降低(P0.05),各组中华鳖血清甘油三酯、总胆固醇含量及碱性磷酸酶活性无显著差异(P0.05)。试验结果表明,添加复方中草药能提高中华鳖的生长性能,添加量以1%为宜。     

关于在饲料中利用淡水鱼内脏油的研究

用淡水鱼内脏油作配合饲料脂肪源是行之有效的。采用进口酪蛋白、糊精、纤维素、矿物剂及维生素为基础原料，配制四组不同的等量单一脂肪源饲料及四组不等量的相同脂肪源饲料，通过６０ｄ的团头鲂喂养试验，以鱼体增重率、饲料系数、蛋白质效率为试验评定指标，得出：（１）精制鱼油较粗制鱼油为好，添加效果均优于豆油，淡水鱼内脏油是一种理想的饲料脂肪源；（２）精制淡水鱼内脏油与海水鱼油饲养效果相当，淡水鱼内脏油可以部分或全部取代海水鱼油；（３）配合饲料中添加４％～６％的淡水鱼内脏油，不仅可加快鱼体的生长，而且能降低饲料成本，提高蛋白质利用率。     

不同脂肪源对克氏原螯虾生长性能与肠道菌群的影响

为研究饲料中不同脂肪源对克氏原螯虾(Procambarus clarkii)生长、营养代谢及其肠道菌群组成的影响,本实验通过在人工配合饲料中分别添加5%的豆油(SO)、鱼油(FO)、猪油(LO)和混合油(豆油∶鱼油=1∶1,MO)作为主要脂肪源,对克氏原螯虾进行60 d饲喂实验后检测其生理生化指标与肠道菌群组成。结果显示：不同脂肪源对克氏原螯虾存活率与特定生长率影响显著,MO组存活率与特定生长率均为最高,LO组均显著低于其他组;营养代谢指标检测结果显示,LO组肝胰脏的脂肪酶、谷丙转氨酶、谷草转氨酶和血清的总胆固醇均显著高于其他实验组;运用16S rDNA高通量测序技术对肠道微生物组成进行测定,结果显示四个组共有优势菌属只有拟杆菌属(Bacteroides),可见脂肪源是克氏原螯虾肠道菌群的较大影响因素;未知的RsaHf231菌属和Anaerorhabdus＿furcosa＿group属是除了SO组外其他三组的共有优势菌群;柠檬酸杆菌属(Citrobacter)是SO组和FO组的优势菌群;Candidatus＿Bacilloplasma是MO组特有优势菌群。综上所述,混合油更能满足克氏原...     

不同水平亚麻籽油对罗非鱼肝功能和脂质代谢的影响

在基础饲料中分别添加0%、1.5%、3.0%、4.5%的亚麻籽油(LO)配制4种等氮(粗蛋白质33%)试验饲料,在淡水循环养殖系统中,分别饲喂初均重为(9.15±0.03)g的吉富罗非鱼(Oreochromis niloticus)8周,研究饲料中添加亚麻籽油对罗非鱼肝功能和脂质代谢的影响。结果显示:4.5%LO组鱼体肝胰脏脂肪和丙二醛(MDA)含量显著高于其他组,而各组间比肝重(HSI)无显著差异。随饲料中LO水平的增加,鱼体肝胰脏EPA、DHA、n-3 PUFA、n-3 HUFA含量及n-3/n-6比例显著升高,而3.0%LO水平后无显著变化。鱼体肝胰脏亚油酸和n-6多不饱和脂肪酸(n-6 PUFA)含量以对照组最高,4.5%LO组最低。各试验组鱼体肝胰脏中油酸、花生四烯酸(ARA)、饱和脂肪酸(SFA)和单不饱和脂肪酸(MUFA)含量无显著差异。随LO添加水平的增加,鱼体血液中胆固醇(CHOL)、甘油三酯(TG)及低密度脂蛋白胆固醇(LDL-C)含量也显著升高。而4.5%LO组血液中高密度脂蛋白胆固醇(HDL-C)含量显著低于其他组。4.5%LO组鱼体肝胰脏苹果酸脱氢酶(MDH)活性显著高于其他组,而脂蛋白脂酶(LPL)活性以1.5%和3.0%LO组最高。3.0%LO组鱼体肝胰脏超氧化歧化酶(SOD)和过氧化氢酶(CAT)活性显著高于其他组。而肝胰脏谷丙转氨酶(GPT)和谷草转氨酶(GOT)活性以4.5%LO组最低。结果表明,饲料中添加3.0%的亚麻籽油有利于罗非鱼肝胰脏和机体健康。     

Effects of dietary lipid sources on growth performance,lipid metabolism and antioxidant status of juvenile Russian sturgeon Acipenser gueldenstaedtii

Six isonitrogenous and isoenergetic diets were used to test the influence of lipid source on growth performance, antioxidant status and lipid metabolism of juvenile Russian sturgeon, Acipenser gueldenstaedtii. Each diet was supplemented with 90 g kg^?1 of lipid from each of six sources including fish oil (FO), beef tallow (BT), sunflower oil (SO), linseed oil (LO) and equal combinations of FO + SO + BT (FSB) or LO + SO + BT (LSB). After 56 days, fish fed LSB demonstrated highest weight gain, specific growth rate and lowest hepatosomatic index among all groups. The n‐6 polyunsaturated fatty acids (PUFAs) in the whole fish were highest in the SO group, and n‐3 PUFAs were highest in fish fed LO. The fish fed FO contained highest n‐3 highly unsaturated fatty acids. Triglyceride in the serum of fish fed LSB was lowest, but was not significantly different from that in the SO group. Triglyceride in the serum of fish fed FO and BT was highest among all groups. Lipase, malate dehydrogenase and lipoprotein lipase activities were highest in fish fed LSB. Serum malondialdehyde in fish fed LSB was significantly lower than in fish fed FO or SO, but no significant differences were found among fish fed LSB, BT, LO or FSB. Fish fed LSB showed higher catalase activity and total antioxidant capacity than fish fed FO or FSB. This study indicates that linseed, sunflower oil and BT mixed oil are a suitable lipid source and can benefit growth performance and antioxidation in juvenile sturgeon.     

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.     

Effects of Different Dietary Lipid Sources on Growth Performance,Fatty Acid Composition,and Antioxidant Enzyme Activity of Juvenile Rockfish,Sebastes schlegeli

This study was carried out to investigate and compare the effects of various dietary lipid sources on growth performance, body composition, fatty acid profiles, and hepatic and plasma antioxidant enzyme activities of juvenile rockfish, Sebastes schlegeli. Three replicate groups of fish (initial mean weight, 1.7 ± 0.04 g) were fed four isonitrogenous and isolipidic diets containing either fish oil (FO), soybean oil (SO), linseed oil (LO), or a mixture of SO and LO (SO + LO) for 8 wk. There were no significant differences in survival, weight gain, feed efficiency, and protein efficiency ratios of fish fed the diets containing different lipid sources (P > 0.05). The fatty acids compositions of the liver and muscle tissues reflected the dietary fatty acid compositions. Liver and muscle of fish fed the SO diet had high concentration of linoleic acid, whereas those of fish fed the LO diet were rich in linolenic acid. Liver and muscle of fish fed the FO diet had significantly (P < 0.05) higher levels of eicosapentaenoic acid and docosahexaenoic acid than those of fish fed the SO and LO diets. Dietary lipid source had no significant effect on the hepatic and plasma enzyme activities of superoxide dismutase and glutathione peroxidase. The results of this study suggest that SO and LO can be used as a replacement for FO in the diets of juvenile rockfish without incurring any negative effects on growth, feed utilization, and antioxidant enzyme activity, when the dietary essential fatty acid requirements are satisfied for rockfish.     

Effects of different dietary lipid sources on growth performance,body composition and lipid metabolism‐related enzymes and genes of juvenile golden pompano,Trachinotus ovatus

Three groups of juvenile golden pompano, Trachinotus ovatus (54.75 ± 0.25 g), were each fed one of three diets containing different lipid sources: fish oil (FO), soybean oil (SO) and lard oil (LO). Fish were reared in sea cages for 8 weeks, and the fish fed the FO diet had significantly higher specific growth rate (SGR) but lower condition factor (CF) than the other treatments. The fatty acid (FA) composition of whole‐body lipids was closely correlated with those in the diets. Although no differences can be found in hepatic fatty acid synthase (fasn) activity, the carnitine palmitoyl transferase 1 (cpt1) activity in fish fed the FO diet was significantly higher compared with other treatments. In addition, the relative gene expression of lipid metabolism‐related enzymes, such as cpt1, fas, apolipoprotein B100 (apoB100), delta‐6 fatty acyl desaturase (fadsd6) and fatty acid‐binding protein 1 (fabp1), was also influenced by the different dietary lipid sources. Serum triglyceride (TG) and glucose content in fish fed the LO and FO diets were significantly higher than those in the SO group. Accordingly, it can be concluded that FO could not be completely replaced by SO or LO in golden pompano diets. The lipid sources of a diet could impose significant influence on body condition factor and hepatic lipid metabolism of golden pompano.     

Effect of dietary lipid source and vitamin E on growth,non‐specific immune response and resistance to Aeromonas hydrophila challenge of Chinese mitten crab Eriocheir sinensis

Six purified diets were formulated to contain three lipid sources, fish oil (FO), linseed oil (LO) and soybean oil (SO), at 6% diet lipid crossing two levels of vitamin E (100 and 300 mg α‐tocopheryl acetate/kg diet) for each lipid source (FO100, FO300, LO100, LO300, SO100, SO300). The juvenile Chinese mitten crab, Eriocheir sinensis, respectively, fed on these diets with four replicates for 6 weeks. The crab weight gain (WG) and specific growth rate (SGR) were significantly affected by dietary lipid sources. No difference was found between the crabs fed two levels of vitamin E, but the WG and SGR were numerically higher in crab fed 300 mg/kg vitamin E than those fed the other level of vitamin E. The lipid source and vitamin E level could affect fatty acid composition in the hepatopancreas. The contents of saturated fatty acids (SAFA) and n‐3HUFA were significantly higher in the crab‐fed fish oil. The highest contents of n‐6PUFA and n‐3PUFA were found in the crab‐fed soybean oil and linseed oil respectively. The contents of SAFA, n‐3HUFA and n‐3PUFA were higher in the 300 mg/kg vitamin E treatment. A lower malondialdehyde (MDA) content and higher phenoloxidase (PO) activity were observed in the crab fed 300 mg/kg vitamin E. The results of this study indicate that the Chinese mitten crab fed the diet with 6% fish oil and 300 mg/kg vitamin E showed better growth, antioxidant capacity and resistance to Aeromonas hydrophila.     

European seabass (Dicentrarchus labrax) ability to discriminate between diets made with different dietary fat sources

The aim of this work was to determine whether juvenile and adult European seabass (Dicentrarchus labrax L.), fed ad libitum manually and with self‐feeding demand feeders, respectively, were able to discriminate between a fish oil‐based diet and a series of diets made with vegetable oils (soybean, linseed, rapeseed and sunflower oil), as well as a fat‐free diet. Adult D. labrax (443.6 ± 108.8 g) selected diets made from soybean (SYO) and rapeseed (RO) in proportions similar to fish oil (FO). Demand levels for the other two diets, sunflower (SUO) and linseed (LO) oils, were significantly lower than FO, whilst juveniles (56.4 ± 11.2 g) displayed a preference for SYO and FO. The lowest demand levels were associated with a fat‐free diet (FF). Selection percentages of the diets for adult and juvenile fish were, respectively, FF—22.96% and 39.76%, SYO—43.02% and 53.26%, LO—36.48% and 36.19%, SUO—39.87% and 37.32%, and RO—46.38% and 40.94%. The animals’ size and feeding method did not significantly affect dietary selection. However, a statistical difference in specific growth rate (1.37% ± 0.26% day^?1) for juveniles was only observed for FO+FF combination. For juveniles, no differences were observed in the conversion index. The juvenile group (FO + FF) had the highest food intake (2.00 ± 0.35 g 100 g^?1 body weight). Moreover, the groups fed FO + SUO and FO + RO consumed the least. In conclusion, this study shows D. labrax can discriminate between diets where the only difference is the lipid source. These findings should be used to understand the acceptance or rejection of different source oils, which are increasingly being used in aquaculture such as aquafeeds for European seabass.     

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.     

Effect of variation in the dietary ratio of linseed oil to fish oil on growth,body composition,tissues fatty acid composition,flesh nutritional value and immune indices in Manchurian trout,Brachymystax lenok

In order to study the effects of linseed oil substitution on the growth, body composition, tissue fatty acid composition, flesh nutritional value and immune indices of juvenile Manchurian trout, five feed types containing different levels of linseed oil (LO) mixed with fish oil (FO) were prepared: 0 (0 LO); 250 g/kg (25 LO); 500 g/kg (50 LO); 750 g/kg (75 LO); and 1000 g/kg (100 LO); and fed to juvenile Manchurian trout (initial weight 6.43 ± 0.02 g) for 9 weeks. The results showed that substitution of FO with 750 g/kg LO did not affect the growth of juvenile trout, with protein content in the dorsal muscle, and lipid content in the liver not showing any significant difference (p > 0.05). The highest lipid content found in muscle samples occurred for the 25 LO diet. The fatty acid composition found in the dorsal muscle and the liver of the Manchurian trout reflects the fatty acid composition in the diet, where the relative amount of linolenic acid (ALA), linoleic acid (LA) and docosahexaenoic acid (DHA) found in these organs has a positive linear correlation with their relative composition in the diet (p < 0.05). As the amount of LO in the diet was increased, the composition of ALA found in the sampled organs increased, while the composition of DHA and eicosapentaenoic acid (EPA) decreased. At the same time, the index of atherogenicity (IA) and thrombogenicity (IT) of the muscle samples from the 75 LO and 100 LO diets was significantly lower than for the 0 LO and 25 LO diets (p < 0.05), while the flesh lipid quality (FLQ) in the 100 LO diet was significantly lower than for the other diets (p < 0.05). The aspartate transaminase (AST) activity decreased initially, and then increased, as the level of LO replacement for FO was increased, with the 25 LO diet being significantly lower than for other groups (p < 0.05). The alanine aminotransferase (ALT) activity in serum samples from the 100 LO diet was higher than that from other diets. The lysozyme (LZM) activity in both serum and liver tissue first increased to a peak for the 25 LO and 50 LO diets, respectively, and then decreased as the level of LO was further increased. There was no significant change in the alkaline phosphatase (AKP) activity in the liver samples; however, the acid phosphatase (ACP) activity decreased significantly from the highest value for 0 LO feed group. In conclusion, the composition of fatty acids in the dorsal muscle and the liver was found to be modified by the diets, and with the diet containing less than 750 g/kg LO, being both beneficial for growth, and improved immunity, while maintaining the nutritional value of the lipid content in the dorsal muscle during the 9‐week period.     

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.