相同EAA模式下不同日粮蛋白水平对草鱼肌肉、肝胰脏蛋白周转代谢的影响

在日粮必需氨基酸模式相同条件下 ,研究不同日粮蛋白水平对草鱼肌肉、肝胰脏蛋白质周转代谢的影响。其中周转代谢参数包括 :蛋白质的合成速率 (FSR)、降解速率 (FDR)、生长速率 (FGR)、合成能力 (CS)、合成的翻译效率 (KRNA)和蛋白质沉积效率 (PRE)。试验结果表明 :1.日粮蛋白水平的增加促进了草鱼的生长 ,促进了肌肉、肝胰脏蛋白质的增长。饲料转化效率和肌肉蛋白质沉积效率在适宜蛋白水平时最高。2.肌肉FSR、FDR与日粮蛋白水平呈正相关关系 ;肝胰脏蛋白FSR不受日粮蛋白水平的影响 ,蛋白质FDR与日粮蛋白水平呈负相关关系。3.肌肉蛋白FGR的增加归因于蛋白质合成的增长较降解的增长更占优势 ,以及蛋白质合成的KRNA 的提高 ;肝胰脏蛋白FGR的增加归因于蛋白质降解的减少。4.肌肉、肝胰脏蛋白CS不受日粮蛋白水平的影响。5.肌肉PRE(生长占合成的比例 )在适宜蛋白质水平 (30 % )时最高 ,而且在该水平下饲料系数最低 ,即饲料转化率最高     

用光合细菌菌液池塘培育淡水鱼种的试验

光合细菌(photosynthetic bacteria)简称为PSB,是种营养价值较高且营养组份较全的细菌。在厌氧弱光条件下,具有处理低分子有机物,净化水质等显著功效。当前,在淡水、能源、饲料粮三紧缺的条件下,将其用于池塘养殖中,能获得节水节电节省饲料粮的效果。同时利用PSB富含维生素(尤以B族维生素最多)和辅酶Q等生理活性物质,将PSB混拌添加于鱼种精饲料内或泼洒于池塘中。通过提高鱼种饵料的营养水平,增强鱼种抗病力和改善鱼池水质,以达到提高鱼种成活率和增产、降低成本之目的。用PSB菌液进行链、鳙、草鱼、鲂夏花的池塘育种并育成11.8厘米左右的大规格鱼种试验,迄今尚未见正式报导,为此,我们于1989年在山东省济宁市郊区淡水养殖试验场做了此项试验,现报告如下。     

池养条件下湖白鲑幼鱼的生长和食性的观察

池塘饲养的湖白鲑，其幼鱼的体长与日龄呈直线相关，体重与日龄，体长与体重均呈幂函数相关。此外，还对湖白鲑幼鱼做了食性的分析：湖白鲑幼鱼阶段是以动物性铒料为主的杂食性。     

鱖鱼1龄鱼种培育试验

本试验探索了地塘培育鱖鱼1龄鱼种过程中鱼池准备、饵料鱼配套、病害防治等一整套养殖技术措施。经过3个月试验,鱖鱼规格从3厘米/尾达到100克/尾,成活率64.4％。     

Evaluation of the Economics of Multi-Batch Channel Catfish Ictalurus punctatus Production Fed an Industry Standard and Three Alternative Diets

The purpose of this study was to determine the feasibility of growing marketable channel catfish, Ictalurus punctatus, from pond-run fingerlings (15.9 g/fish) using low stocking densities (7,413 or 14,826 fish/ha) and electrified bug lights to enhance natural forage available to fish. Even at low stocking densities, fish only averaged 0.2 kg at the end of the growing season. Because marketable sizes of fish were not reached over the growing season, stocking small fingerlings at these rates would not be practical under most commercial production scenarios. Nutritionally, captured insects from electrified bug lights were near a complete diet for catfish, but bug lights did not capture sufficient quantities of insects to affect fish production in either stocking density. Stocking small fingerlings at low stocking rates does not produce market‐sized catfish during one growing season; commercially available bug lights did not provide adequate amounts of natural forage to affect production variables.     

Effects of night‐time light intensity on the survival rate and stress responses in juvenile Pacific bluefin tuna Thunnus orientalis (Temminck and Schlegel)

Land‐based cultured juvenile Pacific bluefin tuna Thunnus orientalis (PBT) have high mortality rates due to collisions or contacts with tank walls after about 30 days of hatching. To determine the effect of night‐time lighting on their survival, juvenile PBT were reared under four different night‐time light intensities (0, 5, 15 and 150 lx) for 9 days, followed by a 3‐day observation period. High‐intensity, night‐time lighting (150 lx) significantly improved the survival rate (75.8%; P < 0.001) compared with the unlit control group (0 lx, 64.3%). The survival rate in the high‐intensity group decreased after the end of the lighting period. Lighting did not influence whole‐body cortisol levels, glucose levels, or diel changes in plasma cortisol levels. In contrast, the survival rates of fish exposed to light intensities between 5 and 15 lx were slightly lower than that of the unlit control group. These results suggest that providing night‐time lighting of 150 lx or higher is an effective method for reducing the mortality of cultured PBT.     

Dietary l‐lysine requirement of fingerling stinging catfish,Heteropneustes fossilis (Bloch) for optimizing growth,feed conversion,protein and lysine deposition

Dietary lysine requirement of fingerling Heteropneustes fossilis (6.96 ± 0.05 g) was quantified by conducting 12‐week feeding trial in a flow‐through system at 28°C. Casein–gelatin based isonitrogenous (38% CP) and isocaloric (14.7 kJ g^?1 DE) amino acid test diets with six levels of dietary lysine (1.5%, 1.75%, 2.0%, 2.25%, 2.5%, 3.0% dry diet) were fed to apparent satiation in triplicates. Broken‐line and second‐degree polynomial regression analyses at 95% plateau of absolute weight gain (AWG; g fish^?1), feed conversion ratio (FCR), protein deposition (PD; g fish^?1) and lysine deposition (LD; g fish^?1) exhibited lysine requirement between 2.0% to 2.3% of the dry diet, corresponding to 5.3–6.1% protein.     

Dietary tryptophan requirement of fingerling Catla catla (Hamilton) based on growth,protein gain,RNA/DNA ratio,haematological parameters and carcass composition

A 12‐week feeding trial was conducted in eighteen 70 L indoor polyvinyl circular troughs provided with a water flow‐through system (1–1.5 L min^?1) at 28 ± 1 °C to evaluate the dietary tryptophan requirement of fingerling Catla catla (3.45 ± 0.24 cm; 0.60 ± 0.13 g). Six casein‐gelatin‐based amino acid test diets (330 g kg^?1 crude protein; 13.6 kJ g^?1 digestible energy) containing graded levels of L‐tryptophan (1.0, 1.4, 1.9, 2.3, 2.8, 3.4 g kg^?1 dry diet) were fed to triplicate groups of fish near to satiation at 08:00, 12:30 and 17:30 h. Absolute weight gain, feed conversion ratio, protein gain, RNA/DNA ratio, hepatosomatic index, viscerosomatic index, condition factor and haematological indices improved with the increasing levels of tryptophan from 1.0 to 2.3 g kg^?1 of dry diet. Significantly higher carcass protein was obtained at 2.3 g tryptophan per kilogram of the dry diet. Exponential analysis of absolute weight gain, feed conversion ratio, protein gain and RNA/DNA ratio against dietary tryptophan levels at 95% maximum and minimum responses displayed the tryptophan requirement at 2.5, 2.3, 2.5 and 2.1 g kg^?1 dry diet, respectively. Inclusion of dietary tryptophan in the range of 2.1–2.5 g kg^?1 dry diet, equivalent to 6.4–7.6 g kg^?1 dietary protein, is recommended in formulating tryptophan‐balanced feed for the culture of this fish species.     

Effect of tank wall colour and pattern on the survival rate of juvenile Pacific bluefin tuna Thunnus orientalis (Temminck and Schlegel) during ship transportation

Juvenile Pacific bluefin tuna (Thunnus orientalis; PBT) often experience high mortality during ship transportation. This study investigated whether the addition of colours or patterns to the walls of tanks affected survival rate. In the first experiment, three colours and lattice patterns were tested: dark blue single‐colour, red single‐colour, and red–blue lattice pattern. Fish in all tanks exhibited abnormal behaviours when sunlight entered the tanks between 0800 and 1000 hours, but mortality only increased in the single‐coloured tanks as a result of collision with the tank walls. In the second experiment, four colours and patterns were tested: dark blue single‐colour, red–blue lattice pattern, red–blue lattice pattern with shade sheet and red–green lattice pattern with shade sheet. Again, we visually observed that fish in all treatment groups exhibited abnormal behaviour when sunlight entered the tanks, but there were no collision deaths in the lattice‐patterned tanks and survival in this group was significantly higher than in the single‐coloured tanks. Thus, the use of a high‐contrast colour pattern can prevent mass death of juvenile PBT during ship transportation.     

铜对刀鲚幼鱼的急性毒性及对肝抗氧化酶活性与组织结构的影响

采用静水生物测试法研究铜(Cu²⁺)对刀鲚(Coilia nasus)幼鱼的急性毒性并进行安全性评价。根据预实验结果, 设定0.3、0.54、0.96、1.68 和3 mg/L 5个CuSO₄浓度梯度进行急性暴露实验, 以肝组织超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性为指标, 并通过观察肝、鳃组织病理变化来研究Cu²⁺污染对刀鲚幼鱼的毒性效应。结果表明, 刀鲚幼鱼随Cu^{2 +} 浓度升高毒性效应逐渐增强, 24、48、72和96 h LC₅₀分别为1.087、1.062、1.042和0.967 mg/L, 安全质量浓度为0.009 67 mg/L。刀鲚幼鱼暴露24 h之后, 各Cu²⁺浓度处理组(0.1, 0.2, 0.3 mg/L) CAT活性、SOD活性显著提高(P<0.05); 暴露48 h后, 各组CAT活性下降, CAT活性均低于对照组, 下降幅度与Cu^{2 +}质量浓度呈正相关, SOD活性提高显著(P<0.05); 暴露72 h后, SOD活性有所下降, SOD活性均低于对照组(P<0.05)。1.68 mg/L和3 mg/L的Cu²⁺浓度对刀鲚幼鱼的鳃和肝都造成严重的损伤, 暴露在高浓度组(3 mg/L)中的刀鲚, 其鳃上皮细胞肿大变性, 鳃小片几乎全部脱落; 肝呈黄色, 超微结构发现肝细胞明显增大, 线粒体空泡化, 胞质中出现空泡和大量脂滴, 表明Cu²⁺可诱发刀鲚出现脂肪肝综合征。SOD、CAT活性变化以及鳃、肝结构变化都反映刀鲚幼鱼受伤害的程度, 可用作安全性风险评价的参考依据。