不同LED光谱对红鳍东方鲀幼鱼生长、摄食及消化酶活性的影响

为探究不同 LED 光谱对红鳍东方鲀(Takifugu rubripes)幼鱼摄食、生长发育和生理活性的影响, 选取 525 尾红鳍东方鲀幼鱼养殖在海水循环水养殖系统中, 分别用 5 种不同 LED 光谱(红、黄、蓝、绿、白)照射处理 30 d, 光周期为 12 L : 12 D, 实验期间测定饵料转化效率, 实验结束时测定其存活、生长指标及消化酶活性。结果表明, 不同 LED 光谱对红鳍东方鲀幼鱼的存活、生长和摄食的影响具有显著性差异(P＜0.05)。其中绿光组红鳍东方鲀的存活率最高, 为(65.71±0.00)%; 绿光组红鳍东方鲀幼鱼体重最大, 为(29.36±3.78) g。在饵料转化效率方面, 绿光组幼鱼的饵料转换效率显著高于其他各组(P＜0.05)。在消化酶活性方面, 不同 LED 光谱处理组中红鳍东方鲀幼鱼的消化酶活性均存在显著性差异(P＜0.05), 其中绿光组的酸性磷酸酶、碱性磷酸酶、己糖激酶、丙酮酸激酶活性均显著高于其他各处理组(P＜0.05); 绿光组肝脂肪酶活性较高, 显著高于蓝光与黄光组(P＜0.05); 绿光组肠脂肪酶活性显著高于红光、白光组(P＜0.05)。综上所述, 绿光对红鳍东方鲀幼鱼的生长发育具有较好的促进作用。     

在循环水养殖系统中养殖密度对红鳍东方鲀应激反应和抗氧化状态的影响

养殖密度是影响养殖水体水质和鱼类生长性能的重要因素。通过红鳍东方鲀(Takifugu rubripes)循环水养殖试验和硝酸盐氮急性处理试验,分别研究不同养殖密度(12.5~20.0 kg/m^3)和不同硝酸盐氮质量浓度(1.0、25.0、100.0和150.0 mg/L)对养殖水体水质、红鳍东方鲀生长性能、应激反应和抗氧化状态的影响。结果显示:不同养殖密度对红鳍东方鲀养殖水体的pH、氨氮和亚硝酸盐氮质量浓度无显著性影响,但较高密度会导致硝酸盐氮质量浓度显著升高,最高升至24.5 mg/L。在较高养殖密度条件下,红鳍东方鲀的生长性能(终体质量、特定增长率和饲料转化率)和抗氧化能力(总抗氧化能力、超氧化物歧化酶、谷胱甘肽过氧化物酶)较弱,但其脂质过氧化(丙二醛)和应激反应(葡萄糖、乳酸和皮质醇)较强。此外,在硝酸盐氮急性处理试验中,红鳍东方鲀未出现死亡。当硝酸盐氮质量浓度为100.0和150.0 mg/L时,红鳍东方鲀抗氧化能力较弱,而应激反应较强。综上,当养殖密度为16.5 kg/m^3时,红鳍东方鲀的生长和抗氧化状态较好,且应激压力较小,这表明在较高密度条件下,养殖水体硝酸盐氮质量浓度的升高不是引起鱼类生长抑制的主要原因。     

投喂频率对绿鳍马面鲀幼鱼生长和肌肉品质的影响

为研究不同投喂频率对绿鳍马面鲀幼鱼生长性能和肌肉品质的影响,在室内循环水养殖系统中,采用人工配合饲料,以1次/d、2次/d、3次/d、4次/d等4种投喂频率,对体质量(13.8±0.83)g的绿鳍马面鲀幼鱼进行了饲养试验,试验时长为42 d。结果显示,随着投喂频率增加,绿鳍马面鲀幼鱼的终末体质量呈逐渐升高的趋势,特定生长率呈先升后降的变化趋势,其中3次/d组幼鱼的特定生长率最高,显著高于1次/d组(P<0.05);饲料系数也随着投喂频率的增加而升高,3次/d组的饲料系数显著高于1次/d组(P<0.05),4次/d组的饲料系数显著高于1次/d组和2次/d组(P<0.05);肌肉品质方面,4次/d组幼鱼的肌肉粗脂肪含量显著高于1次/d组(P<0.05),不同投喂频率组间肌肉粗蛋白质含量和灰分含量无显著性差异(P<0.05)。综合考虑生长性能和肌肉品质指标,绿鳍马面鲀幼鱼适宜的投喂频率为日投3次。     

饲料蛋白能量比对红鳍东方鲀幼鱼的生长性能、饲料利用和体组成的影响

为探求红鳍东方鲀(Takifugu rubripes)幼鱼饲料的最适蛋白质能量比,以鱼粉和豆粕作为主要蛋白源,鱼油和豆油作为主要脂肪源,配制粗蛋白含量分别为36%、42%和48%,粗脂肪含量分别为8%、12%和16%,蛋能比为17.06~24.20 mg/kJ的9组饲料。投喂初始体重为14.95 g的红鳍东方鲀幼鱼56 d。结果显示,由双因素分析方法得出,饲料的蛋白水平、脂肪水平和蛋能比水平均可显著影响红鳍东方鲀的终末体重、特定生长率(SGR)和饲料效率(FE),且饲料蛋白为36%时,显著低于42%和48%组,但与饲料蛋白为42%和48%组之间相比无显著差异。在饲料脂肪为8%时,显著低于12%组,与饲料脂肪为12%与16%组之间相比无显著差异。此外,饲料的蛋白和脂肪水平对红鳍东方鲀生长和饲料利用的相关指标均无显著的交互作用(P>0.05)。由单因素方差分析得出,终末体重、FE、SGR均是Diet8(48/12)蛋白水平为48%、脂肪水平为12%处理组最高,显著高于Diet1(36/8)蛋白水平为36%和脂肪水平为8%处理组、Diet2(36/12)蛋白水平为36%和脂肪水平为12%处理组、Diet3(36/16)蛋白水平为36%和脂肪水平为16%处理组(P<0.05)与Diet4(42/8)蛋白水平为48%和脂肪水平为8%处理组、Diet5(42/12)蛋白水平为42%和脂肪水平为12%处理组、Diet6(42/16)蛋白水平为42%和脂肪水平为16%处理组、Diet7(48/8)蛋白水平为48%、脂肪水平为8%处理组之间相比无显著差异(P>0.05)。因此,根据研究结果综合考虑生长性能及蛋白质节约效应,红鳍东方鲀幼鱼的最适蛋白水平为42%,脂肪水平为12%,蛋能比为20.75 mg/kJ。     

江蓠、浒苔、藻渣和菌渣替代鱼粉对红鳍东方鲀幼鱼生长性能、相关生化指标的影响

本实验旨在研究江蓠(Gracilaria verrucosa)、浒苔(Enteromorpha prolifera)、藻渣和菌渣替代鱼粉对红鳍东方鲀(Takifugu rubripes)幼鱼生长性能、血清和肝脏生化指标和体组成的影响。实验共制成6种等氮、等脂的饲料,以含鱼粉60%为对照组1和45%鱼粉的为对照组2,分别将10%的江蓠、浒苔、藻渣、菌渣与植物蛋白质配合后替代对照组1饲料中30%的鱼粉,投喂初始体重为(17.33±0.55) g的红鳍东方鲀幼鱼56 d。结果显示,1)浒苔组特定生长率(SGR)显著高于其他5组(P<0.05),藻渣组SGR显著高于对照组2和江蓠组(P<0.05),与对照组1和菌渣组无显著差异(P>0.05);对照组1和浒苔组饲料效率(FER)显著高于对照组2和菌渣(P<0.05),与江蓠和藻渣组无显著差异(P>0.05);对照组1的蛋白质沉积率(PPV)和蛋白质效率(PER)显著高于对照组2和菌渣组(P<0.05),与江蓠、浒苔和藻渣组无显著差异(P>0.05)。2)各组血清和肝脏中谷丙转氨酶(GPT)和谷草转氨酶(GOT)活性均无显著差异(P>0.05)。各组血清丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性均无显著差异(P>0.05)。3)菌渣组鱼体粗蛋白质含量显著高于藻渣组(P<0.05),与对照组1、对照组2、江蓠和浒苔无显著差异(P>0.05);浒苔和藻渣组鱼体粗脂肪含量显著高于对照组2 (P<0.05),与对照组1、江蓠和菌渣组无显著差异(P>0.05)。综合来看,将10%江蓠、浒苔、藻渣和菌渣与植物蛋白质配合后替代饲料中30%的鱼粉对红鳍东方鲀幼鱼的生长性能无不良影响,并且浒苔可以显著提高红鳍东方鲀的生长性能。     

红鳍东方鲀、菊黄东方鲀及其杂交F1幼鱼耗氧率与窒息点研究

利用封闭呼吸室对同一日龄、不同规格的红鳍东方鲀、菊黄东方鲀和菊黄东方鲀(♀)×红鳍东方鲀(♂)杂交F1代幼鱼进行耗氧率和临界窒息点的研究。试验结果表明,水温14.8～15.6℃时,体质量(37.24±3.64)g的红鳍东方鲀幼鱼耗氧率为(0.3385±0.0161)mg/(g.h),体质量(14.45±1.08)g的菊黄东方鲀幼鱼耗氧率为(0.2327±0.0241)mg/(g.h),体质量(27.96±1.38)g的杂交F1代东方鲀幼鱼耗氧率为(0.2282±0.0219)mg/(g.h);同一日龄不同规格红鳍东方鲀、菊黄东方鲀和杂交东方鲀幼鱼的耗氧量分别为(12.5243±0.6720)、(3.3544±0.2975)、(5.8469±0.9537)mg/(h.尾);3种东方鲀的耗氧率呈明显的昼夜节律,白天平均耗氧率显著高于夜晚。水温为14.8～15.6℃时,红鳍东方鲀、菊黄东方鲀及杂交东方鲀幼鱼的临界窒息点分别为0.665、0.882mg/L和0.774mg/L。     

光谱对红鳍东方鲀幼鱼肠道微生物组成的影响

为探究光谱对红鳍东方鲀幼鱼肠道微生物组成的影响，以红鳍东方鲀幼鱼为研究对象，在5种不同光谱(蓝光、绿光、红光、白光、黄光)条件下对其受精卵进行孵化和饲育共90 d。试验结束后对各组幼鱼体长进行测定，采用Illumina HiSeq高通量测序技术对其肠道微生物的组成进行分析。结果显示，绿光组、黄光组和白光组的幼鱼体长显著高于蓝光组和红光组(P<0.05),且幼鱼存活率蓝光组>红光组>黄光组>白光组>绿光组。以相似度为97%的聚类分析显示，蓝光组、绿光组、红光组、白光组和黄光组的红鳍东方鲀肠道微生物的运算分类单元数分别为631、508、530、513、418个，共有运算分类单元数87个，特有运算分类单元数为0,但蓝光组和红光组共有的运算分类单元数为13。蓝光组Ace和Chao指数显著高于黄光组(P<0.05),即蓝光组的微生物菌群的丰富度最大，黄光组最小。蓝光组和红光组Shannon指数显著高于绿光组和黄光组(P<0.05),即蓝光组和红光组的肠道微生物菌群多样性大于绿光组和黄光组。属水平肠道菌群分布显示，弓形杆菌属、弧菌属、支原体等为红鳍东方鲀幼...     

暗纹东方魨幼鱼对蛋白质的最适需要量

以白鱼粉为蛋白源设计了6个不同蛋白质水平(35%,40%,45%,50%,55%,60%)的等能饲料,采用室内水泥池养殖,在水温为24～26℃条件下对暗纹东方鲀幼鱼进行了12周的生长实验以确定其最适蛋白质需要量.增重率和饲料效率随着蛋白质水平的增加而上升,50%试验组的鱼体增重显著高于35%、40%和45%试验组(P＜0.05),蛋白质含量高于50%以后增重不再有显著变化(P＞0.05).蛋白质效率总体上随着蛋白质水平的增加趋于降低,但在35%、40%和50%试验组之间无显著差异(P＞0.05).采用折线模型测算出暗纹东方鲀幼鱼获得最大增长和对饲料利用最佳时的蛋白质水平分别大约是49%和46%,据此估算出暗纹东方鲀幼鱼的最适蛋白质含量为46%～49%,这一结果同红鳍东方鲀的最适蛋白质需要量基本一致.     

红鳍东方鲀幼鱼对饲料中蛋氨酸需求的研究

在半精制饲料中分别添加0、0.30%、0.60%、0.90%、1.20%、1.50%蛋氨酸制成6组等氮等脂饲料,各组蛋氨酸的实际含量分别为0.61%、0.85%、1.10%、1.39%、1.60%、1.84%,对初始体重为(13.83±0.63) g的红鳍东方鲀(Takifugu rubripes)幼鱼在室内流水系统中进行了76 d的喂养实验,探讨其蛋氨酸的需求量。研究表明,当饲料中蛋氨酸水平由0.61%升高至1.60%时,红鳍东方鲀的特定生长率(Specific growth rate,SGR)、饲料效率(Feed efficiency,FE)、蛋白效率比(Protein efficiency ratio, PER)均显著升高(P0.05),且都在1.60%组取得最大值。其中,特定生长率在1.39%、1.60%实验组无显著差异(P0.05),但随着蛋氨酸的进一步升高,特定生长率、饲料效率、蛋白效率比均呈现出下降的趋势;蛋氨酸水平对于蛋白沉积率没有显著影响(P0.05);饲料中蛋氨酸水平对全鱼粗脂肪含量呈现出先升高再降低的趋势,但各组间粗蛋白、水分和粗灰分无显著差异(P0.05);随着蛋氨酸水平升高,肝体比(Hepatosomatic index, HSI)和脏体比(Viscerosomatic index, VSI)呈现先升高再下降,在蛋氨酸含量为1.60%时达到最高,显著高于蛋氨酸0.61%组(P0.05),与其他组无显著差异;血清中甘油三酯、胆汁酸的含量,随着蛋氨酸水平的升高呈现出先升高再降低的趋势,饲料蛋氨酸水平对血清中总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇、总蛋白水平及谷草转氨酶、谷丙转氨酶的活性无显著影响(P0.05)。以特定生长率为评价指标进行一元二次回归曲线分析,得出体重为(13.83～82.47) g的红鳍东方鲀幼鱼的蛋氨酸需求量为1.38%,占饲料蛋白质的2.71%。     

野生菊黄东方鲀与养殖菊黄东方鲀肌肉品质比较

为比较野生菊黄东方鲀与养殖菊黄东方鲀肌肉的品质,采用常规生化方法测定并分析了其肌肉中营养成分及部分氨基酸的含量。结果表明,野生组菊黄东方鲀肌肉中的粗脂肪含量显著高于养殖组(P0.05),粗灰分含量显著低于养殖组(P0.05);16种氨基酸中,野生组有6种氨基酸含量显著高于养殖组(P0.05),而其他氨基酸含量则无显著性差异(P0.05);野生组菊黄东方鲀肌肉中必需氨基酸(EAA)和鲜味氨基酸(DAA)的含量显著高于养殖组(P0.05)。根据FAO和WHO提倡的相关评价指标,在营养、口感味道等方面,野生菊黄东方鲀相对于养殖菊黄东方鲀较优。     

养殖密度对厚颌鲂幼鱼生长、饲料利用及肠道抗氧化应激性能的影响

本研究拟通过养殖实验确定厚颌鲂(Megalobrama pellegrini)幼鱼最适养殖密度;同时,利用酶学和分子生物学手段分析养殖密度对厚颌鲂幼鱼肠道抗氧化酶活性及氧化应激相关基因表达的影响。实验设计5个密度处理组,分别为0.15 kg/m³ (50尾/桶)、0.24 kg/m³ (80尾/桶)、0.34 kg/m³ (110尾/桶)、0.42 kg/m³ (140尾/桶)和0.50 kg/m³ (170尾/桶),每组设置3个平行,实验周期为42 d。结果显示,当养殖密度从0.15 kg/m³ 逐渐升高到0.50 kg/m³ 时,厚颌鲂幼鱼生长(增重率和特定生长率)呈先上升后下降的趋势,且在最大密度时(0.50 kg/m³ )增重率和特定生长率显著低于0.34 kg/m³ 密度实验组(P<0.05)。同时,最高养殖密度处理组(0.50 kg/m³ )饲料系数显著高于中低密度实验组(0.15、0.24和0.34 kg/m³ )(P<0.05),说明过高养殖密度不利于厚颌鲂幼鱼的生长和饲料利用。实验表明,提高养殖密度并未影响厚颌鲂幼鱼成活率(P>0.05),各组存活率均较高(>97%)。当养殖密度为0.34 kg/m³ 时,厚颌鲂幼鱼全鱼粗蛋白和粗脂肪含量显著高于其他各密度实验组(P<0.05)。厚颌鲂幼鱼肠道抗氧化应激相关指标受到养殖密度的显著影响,其中,0.24和0.34 kg/m³ 密度处理组鱼体肠道总抗氧化能力显著高于最低密度组(0.15 kg/m³ )和高密度组(0.42、0.50 kg/m³ )(P<0.05);最高密度实验组(0.50 kg/m³ )肠道超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性最低,而丙二醛(MDA)含量最高(P<0.05);谷胱甘肽(GSH)含量最高值出现在0.34 kg/m³ 处理组,显著高于其他各实验组(P<0.05)。最低密度实验组(0.15 kg/m³ )厚颌鲂幼鱼肠道细胞色素P450(CYP1 A)基因相对表达量显著低于较高密度实验组(0.42 kg/m³ )(P<0.05);最高养殖密度组(0.50 kg/m³ )鱼体肠道转录因子NF-E2相关因子2(Nrf2)基因相对表达量最高,而锰超氧化物歧化酶基因(MnSOD)相对表达量最低,与0.34 kg/m³ 密度处理组间有显著性差异(P<0.05),说明养殖密度过高时能引起鱼体的氧化应激反应。研究表明,体重为0.45~1.36 g的厚颌鲂幼鱼最适养殖密度为0.34 kg/m³ ,该结果可为提高厚颌鲂苗种培育效率,促进其种质资源恢复提供理论基础。     

Effect of Feeding Frequency, Water Temperature, and Stocking Density on the Growth of Tiger Puffer, Takifugu rubripes

Effects of daily feeding frequency, water temperature, and stocking density on the growth of tiger puffer, Takifugu rubripes, fry were examined to develop effective techniques to produce tiger puffer in a closed recirculation system. Fish of 4, 14, and 180 g in initial body weight were fed commercial pellet diets once to five times a day to apparent satiation each by hand for 8 or 12 wk at 20 C. Daily feeding frequency did not affect the growth of 14‐ and 180‐g‐size fish. However, the daily feed consumption and weight gain of the 4‐g‐size fish fed three and five times daily were significantly higher than those of fish fed once daily (P < 0.05). Fish of 4 and 50 g in initial body weight were reared with the pellet diet at 15–30 C for 8 wk. The weight gain of fish increased with increasing water temperature up to 25 C and decreased drastically at 30 C for both sizes. Similar trends were observed for feed efficiency, although 4‐g fish had highest efficiency at 20 C. Effects of stocking density on growth were examined with fish of 8, 13, and 100 g in initial body weight. Fish were reared with the pellet diet for 8 or 16 wk at 20 C. Fish were placed in floating net cages in the culture tank, and the stocking density was determined based on the total weight of fish and volume of the net cage. Fish of 8 g in body weight grew up to 35–36 g during the 8‐wk rearing period independent of the stocking density of 8, 15, and 31 kg/m³ at the end of rearing. Final biomass per cage reached 32, 60, and 115 kg/m³ for 13‐g‐size fish, and 10, 18, and 35 kg/m³ for 100‐g‐size fish, and the growth of the fish tended to decrease with increasing stocking density for both sizes.     

养殖密度对克氏原螯虾幼虾生长、消化酶活力和生理生化指标的影响

以体质量(0.015±0.004)g克氏原螯虾幼虾为研究对象,研究了50、100、300、600、900尾/m25种养殖密度对克氏原螯虾幼虾生长、消化酶活力和生理生化指标的影响,实验周期为30 d。结果显示,克氏原螯虾幼虾的终末体质量随着养殖密度的增大而减小。胃蛋白酶、类胰蛋白酶和淀粉酶活力随着养殖密度的增大表现出减小趋势,纤维素酶和脂肪酶活力在5种养殖密度下变化规律不显著(P>0.05)。克氏原螯虾幼虾体内水分含量在5种养殖密度下差异较小(P>0.05);粗蛋白含量随养殖密度的升高呈增高趋势,由54.02%增高至60.75%(P<0.05);粗脂肪含量不断减少(P<0.05),由26.19%减少至19.19%(P<0.05)。随着养殖密度的增大,克氏原螯虾幼虾肌肉葡萄糖的含量呈下降趋势(P<0.05),甘油三酯、总蛋白、尿素氮和胆固醇含量呈不断增多趋势(P<0.05)。克氏原螯虾幼虾肝胰腺葡萄糖、甘油三酯、总蛋白和尿素氮含量随着养殖密度的增大呈不断增多趋势。结果表明,高密度养殖对克氏原螯虾幼虾生长和消化酶活力具有一定负面影响,体内蛋白、脂肪、葡萄糖和尿素氮等物质的含量也随着养殖密度的增大而发生变化。     

养殖密度对食用褐鳟Salmo trutta生长和水质的影响

在涌泉水温度5.6~10.5℃下,将体质量(17.52±0.22)g的2龄褐鳟Salmo trutta饲养在流水圆柱形平底玻璃钢(半径45cm,高60cm)水槽中,水深40cm,密度分别为6.8kg/m~3(SD1)、10.4kg/m~3(SD2)、14.0kg/m~3(SD3)、17.5kg/m~3(SD4)、21.0kg/m~3(SD5)和24.5kg/m~3(SD6),每个密度组设3个重复,探讨养殖密度对褐鳟生长的影响。70d的饲养结果表明:本试验范围内的放养密度未显著影响2龄褐鳟的存活率(P0.05),净增重随养殖密度的增加而增大。SD5组褐鳟净增重(116.55g/(m~2·d))最大;SD4组褐鳟的日增重(0.25g/d)、增重率(102.07%)和特定生长率(1%/d)显著高于SD3组(P0.05)。随着养殖密度的增加,溶解氧含量(DO)呈极显著下降趋势(P0.01),SD1、SD2、SD3(10.14~11.84mg/L)组极显著高于SD5、SD6组(9.62~11.53mg/L)(P0.05);养殖29d和50d时SD1组NO_2~-含量(0.02~0.06mg/L)与SD3、SD5、SD6组(0.04~0.06mg/L)差异显著(P0.05),其他时间不显著;36d后SD2、SD3(0.17~0.22mg/L)组的NH4-NT显著低于SD6组(0.25~0.38mg/L)(P0.05)。比较分析认为,2龄褐鳟的最佳养殖密度应为17.5kg/m~3,不要低于10.4kg/m~3。     

Effect of stocking density on growth performance,serum biochemical parameters,and muscle texture properties of genetically improved farm tilapia, <Emphasis Type="Italic">Oreochromis niloticus</Emphasis>

The objective of this study was to assess the effects of stocking density on growth performance, serum biochemical parameters, and muscle texture properties of genetically improved farmed tilapia (Oreochromis niloticus, GIFT). Juvenile GIFT with an average initial weight of 12.54?±?0.45 g (mean?±?SD) were randomly stocked in 16 tanks (80 L) in a recirculation aquaculture system at four densities of 10 (D1), 20 (D2), 30 (D3), and 40 (D4) fish per tank for 56 days, with quadruplicate for each density. There were no significant differences in water temperature among the four treatments (P?>?0.05). D4 had the significantly lowest dissolved oxygen content (5.52 vs 5.69–6.09 mg L^?1) (P?>?0.05) and pH (6.63 vs 6.87–7.20) (P?<?0.05). NO₂-N and NH₄-N concentrations significantly increased with increasing stocking density (P?<?0.05). Weight gain (WG) and specific growth rates (SGR) decreased with increasing stocking density. The lowest WG (617.20 vs 660.45–747.06%), SGR (3.52 vs 3.62–3.81% day^?1), and highest feed conversion ratio (1.68 vs 1.53–1.58) were observed in D4. Fish at D4 had significantly lower condition factor (3.11 vs 3.29–3.37%) and survival rate (91.25 vs 97.50%) than those from D1 and D2 (P?<?0.05). With increasing stocking density, serum total cholesterol, triglyceride, and total protein concentrations decreased (P <?0.05) and aspartate aminotransferase and alanine aminotransferase activities increased (P <?0.05). D4 fish had higher moisture content (78.80 vs 76.97%) and lower crude protein content (18.14 vs 19.39%) in muscle than D1 fish (P?<?0.05). Compared to D1 and D2, D3 and D4 had lower muscle hardness (1271.54–1294.07 vs 1465.12–1485.65 g), springiness (0.62–0.65 vs 0.70–0.72), gumminess (857.33–885.32 vs 1058.82–1079.28 g), and chewiness (533.04–577.09 vs 757.53–775.69 g) (P <?0.05). High stocking density resulted in growth inhibition, declines in flesh quality, and disturbance to several serum biochemical parameters.     

Application of Biofloc Technology for the culture of Heteropneustes fossilis (Bloch) in Bangladesh: stocking density,floc volume,growth performance,and profitability

Though Biofloc Technology is a new concept in Bangladesh, it provides advantages for improving aquaculture production in many countries, leading to achieve sustainable development goals. The objectives of this study were to determine the effects of stocking densities on the growth performance of stinging catfish (Heteropneustes fossilis) under Biofloc Technology and assess the economic prospects and business feasibilities. Fingerlings were stocked in unique 5000-L tanks with three stocking densities, i.e., 3500 fish/tank (Treatment-I), 4000 fish/tank (Treatment-II), 4500 fish/tank (Treatment-III). The treatments showed significant differences (P?<?0.05) considering the species-specific growth rate, feed conversion ratio, and protein efficiency ratio. Treatment-I had significantly ((P?<?0.05) higher final biomass (29.51 ± 0.04 kg/m³) than the other treatments. The present findings revealed that using a lower stocking density, the Biofloc Technology reduced ammonia (NH₃), nitrite (NO₂), nitrate (NO₃), TDS, and floc volume but significantly increased the dissolved oxygen. As a result, Treatment-I had generated significantly higher net income (BANGLADESHI TAKA—BDT 86,278.90) over the other treatments. Moreover, the NPV, net BCR, and RoR with 4% and 9% opportunity cost were also significantly higher in Treatment-I than other treatments. The internal rate of return (IRR) and SWOT analysis index indicates that investing in Biofloc Technology is far superior, and a stocking density of 3500 fish/tank (Treatment-I) resulted in a faster investment return.

     

Growout production of camouflage grouper, Epinephelus polyphekadion (Bleeker), in a tank culture system

Growout production of the camouflage grouper, Epinephelus polyphekadion (Bleeker), in a 10-m³-capacity fibreglass tank culture system was evaluated, using hatchery-produced fingerlings (56-59 g initial weight) at stocking densities of five, 15 and 45 fish m^?3. During the first 9 months of a 12-month growout period, the fish were fed twice a day with a moist pellet feed containing 40.9% protein. From month 10 onwards until harvest, the fish were fed moist pellets in the morning and trash fish in the evening at a 1:1 ratio. The final weight of fish at harvest was up to 900 g, with mean weights of 544.6 ± 170.72 g at five fish m^?3, 540.2 ± 150.82 g at 15 fish m-^?3 and 513.3 ± 134.52 g at 45 fish m^?3. The results showed no significant differences (P > 0.05) in growth rate and fish size between the different stocking densities tested. The average daily growth rate ranged from 0.62 to 3.38 g fish^?1 day^?1, with mean weights of 1.49 ± 0.74 g fish^?1 day^?1 at five fish m^?3 through 0.53 to 2.38 g fish^?1 day^?1, 1.32 ± 0.57 g fish^?1 day^?1 at 15 fish m^?3 to 0.48-3.32 g fish^?1 day^?1 and 1.31 g fish^?1 day^?1 at 45 fish m^?3 stocking density. Although up to 100% survival was observed at the lowest stocking density, the survival rate significantly decreased (P < 0.05) with increasing stocking density. The food conversion ratio (FCR) significantly decreased (P <0.05) with increasing stocking densities, showing efficient feed utilization with increasing stocking densities of E. polyphekadion. The FCR averaged 2.1 at a stocking density of 45 fish m^?3. The yield in terms of kg fish produced m^?3 of water used in the culture system significantly increased (P < 0.001) from five to 45 fish m^?3. The yield averaged 17.3 ±0.53 kg m^?3 at a stocking density of 45 fish m^?3. The present results show that the present tank culture system could sustain more biomass in terms of increasing fish stocking densities. The growth performance of E. polyphekadion observed during this investigation has been reviewed with other grouper species.     

复合动植物蛋白部分替代鱼粉对大菱鲆幼鱼生长、体成分及生理生化指标的影响

本研究设计5组等氮等能(粗蛋白为53%,能量为25KJ/g)的实验饲料,以60%的鱼粉饲料组作为对照(D1),豆粕∶花生粕∶鱼溶浆粉∶鸡肉粉(2∶1∶3∶2)的复合蛋白替代40%(D2)、50%(D3)、60%(D4)和70%(D5)的鱼粉,养殖大菱鲆幼鱼(Scophthalmus maximus L.)初始体重(53.0±0.2) g,养殖周期84 d,每天定时(08:00,16:30)投喂2次,投喂量为体重的1.5%～2%。实验结果显示,各处理组之间幼鱼存活率、饲料系数和摄食率均无显著性差异(P0.05);与对照组相比,D4和D5组增重率显著降低(P0.05);肥满度在D2组达到最高值,显著高于D3、D4和D5组(P0.05);脏体比(VSI)、肝体比(HSI)和肠体比(ISI)均在D2组达到最低值,均显著低于D5组(P0.05);复合动植物蛋白替代鱼粉对大菱鲆幼鱼全鱼水分和粗蛋白含量均无显著影响(P0.05);各替代组全鱼粗脂肪含量显著高于对照组(P0.05);全鱼灰分含量在D5组显著低于对照组(P0.05);各组间背肌水分、粗蛋白、粗脂肪和灰分含量均无显著性差异(P0.05);复合动植物蛋白替代鱼粉对鱼体肌肉非必需氨基酸和必需氨基酸总量无显著影响(P0.05);各替代组均显著提高了血清谷草转氨酶和谷丙转氨酶活性(P0.05);总蛋白浓度在D2组显著高于D4和D5组(P0.05);血糖浓度在D2和D3组显著低于其他3组(P0.05);D3、D4和D5组甘油三酯浓度和高密度脂蛋白浓度均显著低于对照组和D2组(P0.05);各替代组胆固醇和低密度脂蛋白浓度均显著低于对照组(P0.05);各组之间碱性磷酸酶浓度无显著差异(P0.05)。研究结果表明,复合动植物蛋白可有效替代50%鱼粉而不影响大菱鲆幼鱼生长性能和部分生理生化指标。     

Growth and Feed Utilization of Captive Wild Black Sea Bass Centropristis striata at Four Different Densities in a Recirculating Tank System

A study to determine the effects of four stocking densities on growth and feed utilization of wild‐caught black sea bass Centropristis striata was conducted in a pilot‐scale recirculating tank system. The outdoor system consisted of 12 insulated fiberglass tanks (dia. = 1.85 m; vol. = 2.17 m³) supported by biological filters, UV sterilizers, and heat pumps. Subadults (N= 525; ×± SD = 249 ± 16.8 g) were stocked at densities of 4.6 fish/m³ (1.18 kg/m³), 16 fish/ m³ (3.91 kg/m³), 25.3 fish/m³ (6.83 kg/m³), and 36 fish/m³ (7.95 kg1m³), with three replicate tanks per treatment. Fish were grown under 35 ppt salinity, 21‐25 C, and under ambient photoperiod conditions. A commercial flounder diet containing 50% protein and 12% lipid was hand‐fed twice daily to satiation for 201 d. Mean (range) total ammonia‐nitrogen, 0.61 (0‐2.1) mg/L, nitrite‐nitrogen, 0.77 (0.04‐3.6) mg/L, and nitrate‐nitrogen 40.1 (0‐306) mg/L were significantly higher (P < 0.0001) in the 25.3 and 36 fish/m³ treatments than in the 4.6 and 16 fish/m³ treatments [0.19 (0.05‐0.5), 0.1 (0.24‐0.63), and 11.9 (1.3‐82.2) mg/L, respectively]. However, there were no significant differences (P > 0.05) in growth (RGR = 196.8‐243.1%; DWG = 2.55‐2.83 g/d; and SGR = 0.55‐0.61%/d), coefficient of variation of body weight (C_wtV., = 0.24‐0.25), condition factor (K = 2.2‐2.4), feed consumption (FC = 1.45‐1.65%/d), and feed conversion ratio (FCR = 1.45‐1.52) among stocking densities. Final biomass densities on day 201 reached 3.48, 12.0, 21.1, and 27.2 kg/m³ at stocking densities of 4.6, 16, 25.3, and 36 fish/m³, respectively. Survival (83.8‐99.1%) did not differ among treatments. Apparent net protein retention (ANPR) was significantly higher (P < 0.005) for fish stocked at the lower densities of 4.6 and 16 fish/m3 (22.5‐23.7%) than for those stocked at 25.3 and 36 fish/m³ (21‐20.1%). There were no significant differences (P > 0.05) in apparent net energy retention (ANER = 55.9‐59.1 %) among stocking densities. Final whole body protein (15.3‐16.3%) and lipid (23.1‐26.4%) levels did not differ significantly (P > 0.05) among treatments. The results demonstrated that growth, survival, and feed utilization were not impaired under stocking densities ranging from 4.6‐36 fish/m³ (3.48‐27.2 kg/m3), despite a slight reduction in water quality at the higher densities. In addition, growth variation and final whole body protein and lipid levels were not influenced by these densities. The results suggest that black sea bass are tolerant of crowding and moderate variations in water quality during intensive culture in recirculating tank systems and that higher stocking densities are possible.