饲料脂肪水平和投喂频率对大黄鱼生长、体组成及脂肪沉积的影响

本实验以我国重要的海水养殖鱼类大黄鱼[初始体质量(13.57±0.33)g]为研究对象,在浮式网箱中进行为期8周的摄食生长实验,探讨饲料脂肪水平和投喂频率对大黄鱼生长、体组成及脂肪沉积的影响。采用3×2双因子实验设计,其中饲料脂肪水平分别为9%、12%和15%,投喂频率分别为2次/天和1次/天。结果表明:投喂频率对大黄鱼特定生长率(SGR)和饲料效率(FER)均有显著影响(P<0.05),而饲料脂肪水平仅对FER有显著影响(P<0.05)。2次/天投喂组的大黄鱼末体质量和SGR均显著高于1次/天投喂组,而饲料效率显著低(P<0.05)。在2次/天投喂时,各个饲料脂肪水平对SGR和FER没有显著影响(P>0.05)。而在1次/天投喂时,随着饲料脂肪水平的提高,SGR和FER均显著提高(P<0.05)。2次/天投喂组的大黄鱼全鱼水分含量显著低于1次/天投喂组,而粗脂肪含量显著高(P<0.05)。大黄鱼全鱼粗脂肪含量随着饲料脂肪水平的增加而显著升高(P<0.05)。然而在1次/天投喂时,饲料脂肪水平未对全鱼体粗脂肪含量产生显著影响(P>0.05)。大黄鱼的肝脏和肌肉脂肪含量、肝体比(HSI)以及脏体比(VSI)受到了饲料脂肪水平的显著影响(P<0.05)。在2次/天投喂时,肝脏和肌肉脂肪含量、HSI以及VSI随饲料脂肪水平的升高而显著增加(P<0.05);而在1次/天投喂时,各个饲料脂肪组大黄鱼肝脏和肌肉脂肪含量、HSI以及VSI均无显著差异(P>0.05)。饲料脂肪水平和投喂频率仅对大黄鱼的生长、饲料效率的影响存在显著的交互作用(P<0.05),而对大黄鱼体组成、形态学指标以及肝脏和肌肉脂肪含量无显著的交互作用(P>0.05)。     

饲料蛋白质水平对三倍体虹鳟生长和肠道组织形态的影响

在水温8～16℃下,将初始体质量为(233.30±0.39)g的三倍体虹鳟Oncorhynchus mykiss饲养在规格为3m×3 m×6 m的网箱中,网箱放在青海省龙羊峡水库,每箱100尾,分别投喂蛋白质水平为35.4%(低蛋白质组)、43.3%(中蛋白质组)和52.4%(高蛋白质组)的等脂等能饲料,每种饲料4个网箱,探讨饲料蛋白质水平对三倍体虹鳟生长和肠道组织形态的影响。80 d的饲养结果表明:随着饲料蛋白质水平的增加,特定生长率、肠道皱襞高度和上皮细胞厚度呈显著上升的趋势(P0.05);与低蛋白组相比,中蛋白组和高蛋白组特定生长率分别高出14.4%和22.1%;肠长指数(肠长/体长×100%)、Zihler指数(肠长(mm)/[10×(体质量(g)~(1/3))])、肠道微绒毛高度和肌层厚度呈显著下降的趋势(P0.05);饲料蛋白质水平对三倍体虹鳟肠道中杯状细胞数量无显著影响(P0.05)。综上所述:投喂高蛋白质水平饲料能促进三倍体虹鳟生长,其原因是投喂高水平蛋白质饲料(52.4%)增大了鱼肠道表面积,提高对饲料的消化吸收率;投喂低水平蛋白质饲料(35.4%)可能导致肠道炎症。     

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%。     

饲料中菜籽油替代鱼油对大黄鱼生长、肌肉脂肪酸组成和体色的影响

以初始体质量为(13.56±0.05)g的大黄鱼为对象,研究饲料中菜籽油替代鱼油对大黄鱼生长、肌肉脂肪酸组成和体色的影响。以鱼油组为对照组,用菜籽油分别替代25%、50%、75%、100%的鱼油,配制5种等氮等脂的实验饲料,在海水浮式网箱中进行为期8周的摄食生长实验。结果显示,饲料中不同水平菜籽油替代鱼油对大黄鱼的存活率(SR)和特定生长率(SGR)均无显著性影响;但饲料系数(FCR)随着替代水平的增加呈上升趋势,在100%替代组显著高于对照组。各处理组之间全鱼粗蛋白质、粗脂肪、灰分和水分含量均无显著性差异。肌肉中脂肪酸和饲料中脂肪酸线性关系分析表明,随着菜籽油替代鱼油水平的升高,大黄鱼肌肉中C18∶0、C18∶1、C18∶2n-6和C18∶3n-3含量不断增加,而C20∶4n-6和C22∶5n-3含量不断降低。肌肉中的饱和脂肪酸(SFA)含量随着替代水平的升高而升高,与饲料中SFA含量的变化趋势相反。菜籽油替代鱼油对大黄鱼腹部皮肤亮度值(L*)无显著性影响,但显著影响了背部皮肤L*值,100%替代组L*值显著高于对照组。对照组腹部皮肤红色值(a*)显著高于替代组;与腹部皮肤红色值相反,对照组背部皮肤红色值低于各替代组。菜籽油替代鱼油对大黄鱼背部和腹部皮肤黄色值(b*)均无显著性影响。研究表明,在本实验条件下,菜籽油替代鱼油对大黄鱼生长和体组成无显著影响,却显著影响了大黄鱼的肌肉脂肪酸组成和体色。     

花幼鱼饲料中脂肪水平适宜量的研究

以等量混合的鱼油、豆油作为添加的脂肪源,设计成脂肪水平为1.62%、3.71%、5.77%、7.96%、9.95%和12.01%的6种饲料进行60 d养殖对比试验研究了饲料中花(Hem ibarbus maculatus)幼鱼脂肪水平适宜量。结果显示:花幼鱼饲料中不同脂肪水平对花的相对增重率、饲料系数和蛋白质效率存在显著差异(P<0.05),其中以投喂脂肪水平为7.96%的饲料花的生长最快,相对增重率为(1066.35±13.15)%;以投喂脂肪水平为5.77%的饲料花对蛋白质利用最高,蛋白质效率为(1.84±0.10);以投喂脂肪水平为5.77%的饲料花对饲料的利用最好,饲料系数仅1.39。研究结果表明:花幼鱼饲料中脂肪含量以5.77%~7.96%为最佳,考虑到饲料成本,把花幼鱼饲料脂肪的最适含量定为6%~7%。     

对两种不同投料方式的大黄鱼肠道菌群结构分析

为了解在不同投喂方式下大黄鱼的肠道微生态结构,研究采用高通量测序的方法对投喂冰鲜饲料和投喂颗粒饲料的大黄鱼的肠道菌群进行高通量测序,分析了肠道菌群结构差异。研究表明:变形菌门(Proteobacteria)、厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)、蓝藻门(Cyanobacteria)是大黄鱼肠道的主要菌群,其中变形菌门的丰度超过了30%;不同投喂组的大黄鱼肠道菌群结构存在一定差异,投喂冰鲜料组大黄鱼肠道内菌群OTUs和菌群的α多样性略低于投喂颗粒料的。     

投喂水平对黄鳝(Monopterus albus)生长、肠道消化酶活性及部分血清生理生化指标的影响

为探究不同投喂水平对黄鳝(Monopterus albus)生长、肠道消化酶活性及血清生理生化指标的影响,分别以初始体重为(68.85±0.44)g和(26.67±0.17)g的2种规格黄鳝为研究对象,大规格按照体重的2.8％、3.6％、4.4％和5.2％投喂;小规格按照体重的3.0％、4.0％、5.0％、6.0％和7.0％投喂;每个处理组设置3个重复,大规格组50尾/箱,小规格组100尾/箱,实验持续56d.实验结果显示,随着投喂水平的增加,2种规格黄鳝增重率、饲料系数、肝体比以及全鱼脂肪含量都显著升高(P＜0.05),但金鱼蛋白含量呈下降趋势.大规格黄鳝在投喂水平为4.4％和5.2％时增重率达到最高水平,且组间差异不显著(P＞0.05);大规格黄鳝肠道脂肪酶和胰蛋白酶活性随投喂水平的增加而显著升高(P＜0.05);大规格黄鳝血清超氧化物歧化酶(SOD)活性、总胆固醇(TC)含量先升后降,血清甘油三脂(TG)含量呈上升趋势;大规格黄鳝在投喂水平为4.4％时,SOD和溶菌酶(LZM)活性达到组间较高水平.随着投喂水平的增加,小规格黄鳝肠道胰蛋白酶活性显著升高(P＜0.05);血清TG、TC含量升高,SOD活性降低,血糖含量呈先升后降趋势.在投喂水平为6％时,小规格黄鳝的SOD和LZM活性均处在较高水平.本研究表明,当大规格黄鳝投喂水平为4.4％、小规格黄鳝投喂水平为5％-6％时,黄鳝的生长性能达到较佳状态.     

投喂策略对牛蛙蝌蚪生长发育及肝肠功能的影响

为研究投喂策略对牛蛙蝌蚪生长发育的影响，建立科学的投喂标准，实验分别设置了4种投喂频率(1、2、3和4次/d)与4个投喂水平(4%、6%、8%和10%)饲养牛蛙蝌蚪，以探究牛蛙蝌蚪合适的投喂策略。投喂频率实验表明，投喂3次/d或4次/d的牛蛙蝌蚪在实验周期内的变态率显著高于投喂1次/d或2次/d的牛蛙蝌蚪，且投喂3次/d的牛蛙蝌蚪增重率最大。变态率与投喂量的比值(MFR)随投喂频率增加而上升，2、3或4次/d显著高于1次/d。投喂频率对已变态牛蛙蝌蚪的肝脏组织结构及肠道蛋白酶、脂肪酶、淀粉酶活性无显著影响。投喂水产实验结果显示，实验周期内牛蛙蝌蚪变态率随投喂水平增加而上升，且8%与10%组已变态牛蛙蝌蚪的均重显著高于4%与6%组，但已变态牛蛙蝌蚪肠道蛋白酶活性随投喂水平升高而降低。8%与10%组已变态牛蛙蝌蚪肝细胞脂滴含量明显增多，脂肪沉积现象明显。8%投喂水平组有益菌属暖绳菌属(绿弯菌门)与鲸杆菌属(梭杆菌门)相对丰度较高，一定程度改善了肠道微生物结构。研究表明，牛蛙蝌蚪每日投喂3次，综合投喂水平8%左右，蝌蚪的生长发育性能较优，兼顾了牛蛙养殖生产效益与蝌蚪肝肠健康，促进了牛蛙产业健...     

复合蛋白替代鱼粉对花鲈生长、消化能力和肠道健康的影响

以初均重为(5.80±0.07) g的花鲈(Lateolabrax maculatus)幼鱼为实验对象,研究复合蛋白替代鱼粉对花鲈生长、消化和肠道健康的影响。用复合蛋白分别替代对照组饲料中0、20%、40%、60%和80%的鱼粉,配制成5种等氮等脂的实验饲料,分别用这5种饲料投喂花鲈70 d;养殖实验期间水温为(29.5±1.5)℃,盐度为29±1,溶解氧≥6.5 mg/L。养殖实验结束后采集样品进行分析,结果显示,20%替代组花鲈生长性能与对照组无显著差异(P>0.05),但随鱼粉替代比例的升高,花鲈增重率(WGR)、存活率(SR)、饲料效率(FE)以及蛋白质效率(PER)显著下降(P<0.05),花鲈肠道蛋白酶活性以及饲料干物质、粗蛋白与粗脂肪表观消化率皆显著降低(P<0.05),且花鲈后肠黏膜组织结构出现损伤,肠道促炎因子TNF-α、IL-1β基因表达量升高,抗炎因子基因IL-4、IL-10表达量相应降低。研究表明,复合蛋白替代花鲈饲料中鱼粉比例不宜超过20%。     

投喂频率对池塘循环水养殖大口黑鲈消化酶、组织结构及脂代谢酶基因表达的影响

为研究池塘工程化循环水养殖模式下投喂频率(2 次/d、3 次/d、4 次/d)对大口黑鲈(Micropterus salmoides)体成分、肠道消化和肝脏组织结构及脂蛋白酯酶(LPL)和肝脂酶(HL)基因相对表达丰度的影响, 选用平均体重为 (5.0±0.4) g 的大口黑鲈为研究对象, 在池塘工程循环水养殖系统中进行为期 120 d 的养殖实验。结果表明, 投喂频率对鱼体全鱼的粗脂肪和灰分含量影响显著(P<0.05); 投喂频率 2 次/d 组的灰分含量显著高于其他两组, 而 2 次/d 组体脂肪含量低于投喂 3 次/d、4 次/d 组, 体水分和粗蛋白含量均不受投喂频率的影响(P>0.05); 投喂频率 2 次/d 组肠道淀粉酶和脂肪酶活性显著高于 4 次/d 投喂组(P<0.05); 投喂频率对大口黑鲈肠道绒毛高度和宽度影响不显著 (P>0.05), 4 次/d 组肠道绒毛排列整齐度下降且肌层厚度显著低于 2 次/d 和 3 次/d 组(P<0.05)。肝脏组织学显示, 投喂频率越高肝脏脂肪堆积加重, 相对于 2 次/d 和 3 次/d 组, 4 次/d 组肝细胞偏移、空泡化的现象较明显。在第 60 天和 90 天, 2 次/d 组 LPL 基因相对表达量显著高于 4 次/d 组(P<0.05); 而在第 120 天时, LPL 的相对表达量在各组间差异不显著(P>0.05)。2 次/d 组 HL 基因相对表达量显著高于 4 次/d 组(P<0.05)。综合分析, 在饱饲投喂条件下, 池塘循环水养殖大口黑鲈的适宜投喂频率为 2 次/d。     

Partial replacement of fish oil by soybean oil on lipid distribution and liver histology in European sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) juveniles

A 12‐week feeding trial was conducted to evaluate the effects of fish oil replacement by soybean oil, on lipid distribution and liver histology of two commercially important finfish species: rainbow trout (Oncorhynchus mykiss) and European sea bass (Dicentrarchus labrax). Sea bass (16.2 ± 0.5 g; mean ± SD) and rainbow trout (52.1 ± 0.5 g) juveniles were fed one of three isonitrogenous (500 g kg^?1 CP) and isoenergetic (19 kJ g^?1) diets, containing 0% (control, diet A), 25% (diet B) and 50% (diet C) soybean oil. At the end of the experiment, lipid deposition was evaluated in muscle, liver and viscera. Cholesterol and triglycerides levels were also determined in plasma. Tissue total, neutral and polar lipid composition (g kg^?1 total lipids) showed no significant differences within species, regardless the dietary treatment. The same trend was observed for plasma parameters (P > 0.05). Viscera were the preferential tissue of lipid deposition, with 252–276 and 469–513 g kg^?1 total lipid content in trout and sea bass, respectively. Dietary fish oil replacement had no effect on either hepatic lipid droplets accumulation or degree and pattern of vacuolization in the observed liver sections. These data suggest that both sea bass and trout can be fed diets containing up to 50% soybean oil without adverse effects on tissue lipid composition or liver histology.     

Effect of Dietary Safflower and Canola Oil on Growth Performance,Body, and Fatty Acid Composition of Rainbow Trout (Oncorhynchus mykiss)

The objective of the present study was to evaluate the effects of the diets enriched with safflower and canola oil on growth, feed utilization, body composition, liver, and muscle fatty acid composition of rainbow trout (Oncorhynchus mykiss). Rainbow trout having approximate initial weight of 97.03 ± 0.10 g were fed the experimental diets containing only fish oil (Group 0SFO), safflower oil (50% safflower oil, Group 50SFO and 33% safflower oil, Group 33SFO), and vegetable oil blend (33% safflower and 33% canola oil, Group 66SFCO) for 45 days. Twenty-five fish were randomly assigned for triplicate treatments and offered the test diets two times daily to apparent satiation. At the end of the experiment, survival was 100% in all treatments. No significant differences in the weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio were found between fish fed with the different experimental diets. The highest hepatosomatic index (HIS) and viscerasomatic index (VSI) was obtained in 50SFO and 33SFO groups, respectively. The moisture, protein, lipid, and ash content in the body composition of the fish increased in all experimental groups. The lipid content was not significantly different among the groups (p > 0.05); however, there was a significant difference in ash content between the control and the other groups (p < 0.05). The experimental diets containing vegetable oil (50SFO and 33SFO groups) and vegetable oil blend (66SFCO group) had significantly higher concentrations of n-6 fatty acids, predominantly in the form of linoleic acid (LA). The n-3 fatty acids were present in significantly higher concentration in the control treatment (0SFO). The fatty acid composition of fish fillet and liver were reflective of the dietary lipid source. While the fillet and liver of fish fed the 50SFO diet was high in linoleic acid (18:2 n-6), fish fed the 66SFCO diet had high concentrations of oleic acid (OA; 18:1 n-9). The present study suggests that fish oil can be replaced by up to 50% with safflower oil and by up to 66% with safflower + canola oil blend in rainbow trout diets with no significant effect on growth.     

Growth, digestibility and nutrient utilization of rainbow trout (Oncorhynchus mykiss) and European sea bass (Dicentrarchus labrax) juveniles fed different dietary soybean oil levels

A shortage of marine raw ingredients, such as fish oil, is predicted in the near future. The use of suitable alternative lipid sources, such as vegetable oils, is crucial for sustainable growth of the aquaculture sector. Three isonitrogenous (50% Crude Protein) and isoenergetic (19 kJ g⁻¹) diets, in which fish oil was gradually replaced by soybean oil (0, 25 and 50% of the oil fraction) were tested for 12 weeks, using European sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) juveniles. No dietary effects (p>0.05) on growth performance, feed conversion, digestibility or body composition were observed with either species. The results obtained suggest the inclusion of soybean oil up to 50% of the dietary lipid is possible, in diets for sea bass and/or rainbow trout juveniles.     

Effect of replacements of fishmeal and fish oil on growth and dioxin contents of rainbow trout

Eight experimental diets were prepared to determine the effect of replacements of fishmeal and fish oil with plant protein and palm oil on the growth and dioxin contents in rainbow trout. The first four diets (FP0, FP5, FP10, and FP15) included fishmeal (55%) with increasing replacement of fish oil by palm oil (0, 5, 10, and 15%). Four other diets (AP0, AP5, AP10, and AP15) were substituted with an alternative protein source and with increasing palm oil content (0, 5, 10, and 15%). Dietary dioxin contents increased as fish oil level increased. Thirty rainbow trout (mean weight 38 g) were fed the experimental diets for 12 weeks. No significant differences in growth performance and feed utilization were observed. Dietary dioxin contents influenced the dioxin contents in the whole body. These results suggest that palm oil could effectively replace fish oil in rainbow trout diets, and reduce the dioxin contents in fish.     

Effects of dietary lipid level and vegetable oil on fatty acid metabolism in Atlantic salmon (Salmo salar L.) over the whole production cycle

Changes in fatty acid metabolism in Atlantic salmon (Salmo salar) induced by vegetable oil (VO) replacement of fish oil (FO) and high dietary oil in aquaculture diets can have negative impacts on the nutritional quality of the product for the human consumer, including altered flesh fatty acid composition and lipid content. A dietary trial was designed to investigate the twin problems of FO replacement and high energy diets in salmon throughout the entire production cycle. Salmon were grown from first feeding to around 2 kg on diets in which FO was completely replaced by a 1:1 blend of linseed and rapeseed oils at low (14–17%) and high (25–35%) dietary oil levels. This paper reports specifically on the influence of diet on various aspects of fatty acid metabolism. Fatty acid compositions of liver, intestinal tissue and gill were altered by the diets with increased proportions of C₁₈ polyunsaturated fatty acids and decreased proportions of n-3 highly unsaturated fatty acids (HUFA) in fish fed VO compared to fish fed FO. HUFA synthesis in hepatocytes and enterocytes was significantly higher in fish fed VO, whereas β-oxidation was unaltered by either dietary oil content or type. Over the entire production cycle, HUFA synthesis in hepatocytes showed a decreasing trend with age interrupted by a large peak in activity at seawater transfer. Gill cell prostaglandin (PG) production showed a possible seasonal trend, with peak activities in winter and low activities in summer and at seawater transfer. PG production in seawater was lower in fish fed the high oil diets with the lowest PG production generally observed in fish fed high VO. The changes in fatty acid metabolism induced by high dietary oil and VO replacement contribute to altered flesh lipid content and fatty acid compositions, and so merit continued investigation to minimize any negative impacts that sustainable, environmentally-friendly and cost-effective aquaculture diets could have in the future. Abbreviations: FO - fish oil; HUFA - highly unsaturated fatty acids acids (carbon chain length ≥C ₂₀ with ≥3 double bonds); LO - linseed oil; RO - rapeseed oil; VO - vegetable oil. This revised version was published online in July 2006 with corrections to the Cover Date.     

Replacement of a large portion of fish oil by vegetable oils does not affect lipogenesis, lipid transport and tissue lipid uptake in European seabass (Dicentrarchus labrax L.)

In order to investigate the impact of dietary lipid sources on mechanisms involved in lipid deposition, three groups of European seabass fingerlings with average initial body weight of 5.2 ± 1.0 g were fed three diets differing only by lipid source. These diets were: 100% anchovy oil (diet A), 40% anchovy oil-60% mix of vegetable oils (35% linseed, 15% palm, 10% rapeseed) (diet B) and 40% anchovy oil-60% mix of vegetable oils (24% linseed, 12% palm, 24% rapeseed) (diet C). After 64 weeks of rearing, when seabass reached the size of 160 g, the activity of lipogenic enzymes (fatty acid synthetase, glucose-6-phosphate dehydrogenase and malic enzyme) in liver and of lipoprotein lipase (LPL) in perivisceral adipose tissue, liver and white muscle were measured. Transport of lipid by lipoproteins was examined by determining plasma lipid composition and lipoprotein classes. Dietary oil source did not modify growth performance or lipid content of flesh and liver of seabass. Replacement of 60% of fish oil by the two mixtures of vegetable oils had no significant effect on hepatic lipogenesis and activity of LPL in liver and adipose tissue. Activity of LPL in white muscle was decreased in fish fed diet C compared to those fed diets A and B. Diets containing the mixture of vegetable oils led to lowered plasma, VLDL and LDL cholesterol levels compared to diet A.It is concluded that replacing 60% of fish oil by the two mixtures of vegetable oils in the feeds of European seabass fingerlings until they reach the size of 160 g has no marked effect on growth performance, lipogenesis and tissue lipid uptake but has a hypocholesterolemic effect.     

Response of Rainbow trout (Oncorhynchus mykiss) to unrefined peanut oil diets: Effect on growth performance,fish health and fillet fatty acid composition

A 60‐day feeding study with rainbow trout, Oncorhynchus mykiss, was conducted to determine the effects of replacement of fish oil (FO) by unrefined peanut oil (PO) on growth performance, feed utilization, body composition, fatty acid composition and serum biochemical and haematological parameters. Rainbow trouts (51.60 ± 0.75 g) were fed five experimental diets formulated by replacing dietary FO with PO at levels of level 0 (PO₀), 1/4 (PO₂₅), 1/2 (PO₅₀), 3/4 (PO₇₅) and 4/4 (PO₁₀₀), respectively. As a result, the best growth performance was observed in fish fed with PO₀ and PO₅₀ diet. No significant differences were detected among the groups in terms of body compositions. Fatty acid profiles of the fish fillets reflected the fatty acid profiles of the feeds that the fishes were fed with. In this study, the haematological parameters detected that there were no significant differences compared to the control group, whereas the serum biochemical parameters generally worsened as the ratio of peanut oil in the ration exceeded half of fish oil. As a conclusion, the results of the study suggested that the unrefined peanut oil could be used as a replacer of fish oil in diets for rainbow trout.     

The potential of soya oil industry products as oil alternatives in rainbow trout (Oncorhynchus mykiss) diet

This study investigated the effects of different soya oil products on growth, nutrient digestibility, and fatty acid composition of muscle in rainbow trout. The products’ ingredients were soap stock, fat powder, crude oil, and refined soya oil as a control. Four experimental diets were formulated by addition of 12 % of each of the four ingredients to a basal diet. Replacement of refined soya oil by the soya oil products did not influence growth performance until 8 weeks (P > 0.05). This replacement, however, reduced fat digestibility in rainbow trout (83.7 vs. 73.3–79.8 %; P < 0.05). Dietary inclusions of fat powder and crude oil led to larger values of protein digestibility than those of refined soya oil and soap stock (P < 0.05). The compositions of saturated and monounsaturated fatty acids of the muscle were similar, but linoleic acid concentration (LA, 18: 2n-6) increased in fish muscle fed refined soya oil compared to the other diets (37 vs. 30–31 %; P < 0.05). Arachidonic acid (ArA, 20: 4n-6) concentration was higher (P < 0.05) in fish fed both fat powder and soap stock than those fed the other diets. In conclusion, refined soya oil can be replaced by soya oil products in rainbow trout diet with no negative impacts on the growth. However, fish fed on diet containing refined soya oil had higher concentration of LA and lower density of ArA. It appears that rainbow trout is capable of digesting soya oil products though the digestibility rate reduced slightly with an increase in saturated fatty acid content.     

The effect of total replacement of fish oil with DHA‐Gold® and plant oils on growth and fillet quality of rainbow trout (Oncorhynchus mykiss) fed a plant‐based diet

This study investigated the effect of the replacement of fish oil (FO) with DHA‐Gold (DHA‐G)‐supplemented plant oils (PO) in rainbow trout fed plant‐protein‐based diets. Five diets (450 mg g^?1 digestible protein and 150 mg g^?1 crude lipid) were fed to rainbow trout (initial weight 37 ± 0.5 g) for 12 weeks in a 15 °C recirculating water system. The lipid inclusion types and levels were FO, PO and PO with DHA‐G supplemented at 30 mg g^?1, 60 mg g^?1 or 90 mg g^?1 of the diet replacement for corn oil. Fish fed 90 mg g^?1 DHA‐G were significantly larger and consumed more feed than fish‐fed PO or FO (218 g and 2.6% bwd^?1 versus 181 g and 2.4% and 190 g and 2.3%, respectively). Feed conversion ratio was significantly increased in fish fed 90 mg g^?1 DHA‐G (0.99) as compared to fish‐fed FO (0.90) and 30 mg g^?1 DHA‐G (0.91). Panellists found trout fillets from fish fed the 90 mg g^?1 DHA‐G diet to have significantly fishier aroma and flavour than fish fed the FO diet. Fatty acid analysis demonstrated that 60 mg g^?1 or 90 mg g^?1 DHA‐G supplementation increased PO fed fish fillet DHA to fatty acid levels equivalent or higher than those fish fed a FO diet.     

大黄鱼幼鱼饲料中大豆磷脂油与菜籽油的适宜配比

配制浓缩大豆磷脂油与精制菜籽油的添加比例分别为0:6、2:4、4:2和6:0的4种等氮、等能和等脂的饲料(P0R6、P2R4、P4R2和P6R0),在海水浮式网箱中,养殖初始体重为(20.84±0.05)g的大黄鱼(Larimichthys crocea)幼鱼51 d,每个处理组设3个重复,每个重复40尾鱼。通过评定2种油脂的不同配比对大黄鱼幼鱼的生长、体组成和脂肪酸组成的影响,以得出大黄鱼幼鱼饲料中大豆磷脂油与菜籽油的适宜配比。结果显示,各组实验鱼的存活率均高于91%,且无显著差异(P0.05)。P2R4组实验鱼的特定生长率显著高于P4R2和P6R0组(P0.05)。P2R4组实验鱼的蛋白质沉积率和脂肪沉积率显著高于P0R6和P6R0组(P0.05)。P0R6和P2R4组全鱼的粗脂肪含量显著高于P4R2和P6R0组(P0.05)。全鱼和肌肉的脂肪酸组成受实验鱼所摄食饲料的脂肪酸组成的影响。P6R0饲料显著降低了实验鱼的肝脏脂肪含量和肥满度(P0.05)。研究表明,大黄鱼幼鱼饲料中浓缩大豆磷脂油与精制菜籽油的适宜配比为2:4。