Effects of dietary vitamin C on growth,flesh quality and antioxidant capacity of juvenile golden pompano Trachinotus ovatus

To investigate the effects of dietary vitamin C on growth, flesh quality and antioxidant capacity of juvenile golden pompano Trachinotus ovatus, a 56‐day feeding trial with five graded levels of dietary VC (D1: 11.69, D2: 34.89, D3: 59.10, D4: 114.26 and D5: 227.93 mg VC per kg of diet) was performed on 375 fish (triplicate groups of 25 fish per diet, initial weight 13.57 ± 0.09 g). Results showed that fish of D3 group exhibited the maximum specific growth rate (SGR) and the highest liver enzymatic activities of catalase (CAT) and glutathione peroxidase (GSH‐PX), which were consistent with the expression levels of cat and gsh‐px. Besides, the D3 group also showed higher contents of protein and lipid, and lower cooking loss, drip loss and malondialdehyde content in muscle than D1 group. The docosahexaenoic acid proportion in muscle increased with increasing dietary VC levels. Furthermore, the lowest expression levels of carnitine palmitoyltransferase1 (cpt1) and peroxisome proliferator‐activated receptor α (pparα) were detected in livers of D3 group. The optimum dietary VC level was 49.73 mg/kg from the broken‐line analysis based on the SGR, in which better growth performance, antioxidative ability and flesh quality were observed in T. ovatus juveniles.     

饲料异亮氨酸水平对卵形鲳鲹消化酶活性和免疫指标的影响

实验旨在研究饲料异亮氨酸(Ile)水平对卵形鲳鲹(Trachinotus ovatus)消化酶活性和免疫指标的影响。以鱼粉、豆粕、花生粕和L-晶体氨基酸为蛋白源,配制含粗蛋白430 g·kg~(-1)的6种等氮饲料,各组分别含有13.2 g·kg~(-1)、15.7 g·kg~(-1)、18.2 g·kg~(-1)、20.7 g·kg~(-1)、23.2 g·kg~(-1)和25.7g·kg~(-1)(以干物质计)异亮氨酸。每组3个重复,每个重复随机放置20尾鱼[初始体质量(6.36±0.03)g],实验时长8周。结果显示,各实验组的肠淀粉酶和胃蛋白酶活性、血清总抗氧化能力(T-AOC)、溶菌酶(LZM)活性、免疫球蛋白M和补体(C3和C4)浓度均随着饲料Ile水平的升高而先上升后下降,这5个指标的较高值出现在18.2 g·kg~(-1)和20.7 g·kg~(-1)组,而较低值则出现在13.2 g·kg~(-1)和25.7 g·kg~(-1)组,上述4组与其他2组差异显著。血清尿素氮和丙二醛(MDA)浓度的变化趋势则与上述7个指标相反,较低值出现在18.2 g·kg~(-1)和20.7 g·kg~(-1)组,且显著低于其他4组。血清超氧化物歧化酶(SOD)活性则随着饲料Ile水平的增加而显著升高,18.2~25.7 g·kg~(-1)这4组SOD活性没有显著性差异。综上所述,饲料Ile水平为18.2~20.7 g·kg~(-1)时,卵形鲳鲹具有较好的消化性能和免疫机能。     

饲料盐藻水平对卵形鲳鲹体色和生长的影响

以初始体质量为(13.88±0.28)g的卵形鲳鲹为试验对象,研究不同盐藻添加量(0.0%、0.1%、0.2%、0.4%、0.8%、1.6%)饲料对其体色和生长的影响。每组设3个平行,每个平行饲养20尾鱼,每日饱食投喂2次(8:00;17:00),试验周期为56d。结果显示,盐藻添加量为0.1%~1.6%时,随着饲料中盐藻水平的提高,卵形鲳鲹背部和腹部黄色值(b*)呈显著上升趋势(P0.05),饲料中添加盐藻可明显改善卵形鲳鲹体色;与此同时,卵形鲳鲹质量增加率和特定生长率随饲料盐藻水平的上升呈下降趋势(P0.05),未添加盐藻的对照组具有最高蛋白质效率和最低饲料系数,且与盐藻添加量为0.4%的试验组差异显著(P0.05),饲料中添加盐藻对卵形鲳鲹生长性能和饲料利用没有明显的促进作用;此外饲料盐藻水平对卵形鲳鲹体成分也没有显著影响(P0.05)。     

Development of plant‐based diets and the evaluation of dietary attractants for juvenile Florida pompano,Trachinotus carolinus L.

Sustainable and profitable commercial aquaculture production of marine fish species is dependent on the development of sustainable protein sources as substitutes for expensive animal meals such as fishmeal (FM). Previous Florida pompano Trachinotus carolinus studies have indicated that poultry by‐product meal (PBM) and meat and bone meal can be used to produce a FM‐free diet if suitable levels of nutrients (such as taurine) are included in the diets. In this study, we attempted to develop an all‐plant protein diet by removing the animal proteins in practical diets for pompano by substituting back select ingredients. A series of eight FM‐free diets were formulated, four systematically replaced soybean meal (SBM) with soy protein concentrate (SPC) and four replaced PBM with SPC. Based on the results, there is no clear disadvantage to the use of SPC as a replacement for SBM. However, the complete removal of PBM resulted in reduced performance. Two additional growth trials were conducted to supplement additional amino acids including glycine, valine and histidine, a proprietary chemical attractant mix, fish protein concentrate and squid hydrolysate to improve the growth of pompano when fed all‐plant protein diets. The only improvement in performance occurred with the squid hydrolysate. These results demonstrate that using soybean meal, soy protein concentrate and corn gluten meal as the primary protein sources, a plant‐based feed formulation can be developed, but the removal of all animal proteins is not yet feasible.     

Long‐chain polyunsaturated fatty acid metabolism in carnivorous marine teleosts: Insight into the profile of endogenous biosynthesis in golden pompano Trachinotus ovatus

Golden pompano Trachinotus ovatus is an important farmed carnivorous marine teleost. Although some enzymes for long‐chain polyunsaturated fatty acid (LC‐PUFA) biosynthesis have been identified, the ability of T. ovatus for endogenous biosynthesis is unknown. Here, we evaluated in vivo LC‐PUFA synthesis in a 56‐day culture experiment using six diets (D1–D6) formulated with linseed and soybean oils to produce dietary linolenic/linoleic acid (ALA/LA) ratios ranging from 0.14 to 2.20. The control diet (D0) used fish oil as lipid source. The results showed that, compared with the corresponding indices of fish fed D0, the weight gain rate and specific growth rate as well as the contents of eicosapentaenoic (EPA) and docosahexaenoic acids in tissues (liver, muscle, brain and eye) of D1–D6 groups were significantly lower (p < .05). These data suggested that T. ovatus could not synthesize LC‐PUFA from C₁₈ PUFA or such ability was very low. However, tissue levels of 20:4n‐3 in fish fed diets D1–D6 were higher than that of D0 fish (p < .05), and positively correlated with dietary ALA/LA ratio, while levels of EPA showed no difference among the D1–D6 groups. These results indicated that Δ5 desaturation, required for the conversion of 20:4n‐3 to EPA, may be lacking or very low, suggesting incomplete LC‐PUFA biosynthesis ability in T. ovatus.     

卵形鲳鲹幼鱼饲料中适宜蛋白能量比的研究

以鱼粉、豆粕为蛋白源,豆油、鱼油为脂肪源,配制9种不同蛋白能量水平的饲料,蛋白质3个水平(38%、43%、49%),每个蛋白水平设3个脂肪梯度(6%、10%、14%),其蛋白能量比为19.3～27.4mg/kJ。卵形鲳鲹初始质量为(25.02±0.16)g,每个处理设3个重复,每个网箱(1.5 m×1.0 m×2.0m)放养卵形鲳鲹苗20尾,养殖试验持续8周。结果显示,卵形鲳鲹特定生长率随饲料蛋白水平的升高而显著升高(P<0.05)。投喂含43%或49%蛋白质、6%脂肪饲料的卵形鲳鲹表现出较好的特定生长率。饲料中不同的脂肪水平未表现出蛋白质节约效应,较高的脂肪水平反而抑制了卵形鲳鲹的特定生长率、饲料效率和蛋白质效率。卵形鲳鲹鱼体蛋白和脂肪含量分别随饲料蛋白质和脂肪水平的上升而显著升高(P<0.05)。在该试验条件下,卵形鲳鲹幼鱼饲料中最适蛋白质、脂肪水平和蛋白能量比分别为43%、6%和24.4 mg/kJ。     

三种饲料对卵形鲳鲹幼鱼消化酶活性的影响

[目的]探讨饵料与卵形鲳鲹幼鱼消化酶活性的关系。[方法]以浮性饲料、沉性饲料、鱼浆加鳗粉喂养卵形鲳鲹幼鱼21d后,比较了3种饵料对胃、肠、肝胰脏和幽门盲囊消化酶活性的影响。[结果]胃、肠和幽门盲囊蛋白酶均以摄食鱼浆加鳗粉组增加幅度最大,肝胰脏蛋白酶以摄食浮性饲料增加幅度最大,蛋白酶活性均以摄食沉性饲料增加幅度最小。胃淀粉酶以摄食沉性饲料组增加幅度最大,肠、肝胰脏和幽门盲囊淀粉酶均以摄食浮性饲料增加幅度最大,淀粉酶活性均以摄食鱼浆加鳗粉组增加幅度最小。胃、肠、肝胰脏和幽门盲囊脂肪酶均以摄食鱼浆加鳗粉增加幅度最大,均以摄食浮性饲料增加幅度最小。[结论]该研究结果对合理配合饲料养殖有一定的指导作用。     

卵形鲳鲶消化酶活性的研究I．成鱼和幼鱼消化酶活性在不同消化器官中的分布及其比较

比较研究了卯形鲳够（Trachinotus ovatus）成鱼和幼鱼阶段消化酶（蛋白酶、淀粉酶、脂肪酶）在不同消化器官中的活性。结果表明：1）成鱼蛋白酶在不同消化器官中的活性大小依次为胃〉前肠〉中肠〉幽门盲囊〉后肠〉肝；淀粉酶活性为前肠〉后肠〉幽门盲囊〉中肠〉肝〉胃；脂肪酶活性为前肠〉中肠〉后肠〉幽门盲囊〉肝〉胃。2）幼鱼蛋白酶在不同消化器官中的活性大小依次为胃〉肠〉幽门盲囊〉肝；淀粉酶活性为肠〉幽门盲囊〉肝〉胃；脂肪酶活性为肠〉幽门盲囊〉肝〉胃。3）成鱼不同消化器官中蛋白酶和淀粉酶的活性均小于幼鱼，成鱼胃和幽门盲囊的淀粉酶活性与幼鱼的差异显著；幼鱼胃脂肪酶活性大于成鱼，但其他器官的活性均小于成鱼。卵形鲳鳕幼鱼不同消化器官中的3种消化酶活性大小顺序与成鱼基本相似。     

Nutrients removed by Kappaphycus alvarezii (Rhodophyta, Solieriaceae) in integrated cultivation with fishes in re-circulating water

The potential of the red alga Kappaphycus alvarezii to remove nutrients was tested to treat effluents of Trachinotus carolinus fish cultivation, and the production of carrageenan in this condition was analyzed. Experiments were conducted in four tanks of 8000 L with approximately 1200 fishes of 30 g each integrated with three tanks of 100 L with 700 g of K. alvarezii, as initial biomass per tank. Seawater was re-circulated between tanks with seaweed and with fish. As a control, three tanks with seawater circulating in an open system were utilized. Seawater samples were collected daily for 10 days and concentrations of nitrate, nitrite, ammonium and phosphate were determined in the inflow and outflow water of the tanks. Significant differences between both collecting points were considered as nutrient removal by the seaweed. Growth rates and carrageenan yields were also analyzed in seaweed cultivated in seawater and in effluents. Growth rates of seaweed cultivated in tanks were lower than those obtained in open sea and in laboratory cultivation. Effluents had concentrations of nitrate and nitrite ca. 100 times higher than in the control. Maximum values of nutrient removal on effluents were: nitrate = 18.2%; nitrite = 50.8%; ammonium = 70.5% and phosphate = 26.8%. All plants survived throughout the experimental period, but some developed “ice–ice”, a disease associated with physiological stress. After the experimental period, some plants selected and cultivated in open sea presented higher growth rates in 40 days, indicating nutrient storage. No significant differences between carrageenan yields of K. alvarezii cultivated in seawater and in the effluents were observed. Our results show that K. alvarezii can be utilized as a biofilter for fish cultivation effluents, reducing the eutrophication process and can also be processed for carrageenan production, which provides an additional benefit to the fisheries.     

卵形鲳鲹 JAK3 蛋白的原核表达与纯化

【目的】纯化获取卵形鲳鲹(Trachinotus ovatus)JAK3(TroJAK3)重组蛋白,为了解TroJAK3蛋白功能、相互作用及抗体制备奠定基础。【方法】应用分子生物学技术构建重组质粒pET-32a-TroJAK3,转化大肠杆菌BL21感受态细胞,经IPTG诱导表达,SDS-PAGE和Western blot检测TroJAK3重组蛋白表达情况。【结果】PCR扩增片段长度为3 333 bp,经双酶切鉴定、测序确认序列和开放阅读框正确,结果显示成功构建重组质粒pET-32a-TroJAK3。经终浓度为1 mmol/L IPTG 37℃诱导4 h后进行SDS-PAGE检测,结果表明TroJAK3重组蛋白以包涵体形式大量表达,分子量约为140 ku。经Ni-IDA树脂柱纯化,获得纯化的重组蛋白。Western blot检测结果显示有140 ku的条带,表明TroJAK3重组蛋白能被抗His抗体识别。【结论】成功构建了重组质粒pET-32a-TroJAK3,纯化得到高纯度的TroJAK3融合蛋白。