Apparent digestibility coefficients of selected protein feed ingredients for loach Misgurnus anguillicaudatus

Apparent digestibility coefficients of dry matter, crude protein, lipid and energy, and amino acids availability in white fish meal, brown fish meal, meat meal, fermented soybean meal, soybean meal and rapeseed meal were determined for loach (Misgurnus anguillicaudatus) (12.05 ± 0.21 g), using a reference diet with 5 g kg^?1 chromic oxide and test diets that contained 700 g kg^?1 reference diet, by weight, and 300 g kg^?1 of the test feed ingredients. The juvenile loach was held in 300‐l tanks at a density of 30 fish per tank. White fish meal, brown fish meal, meat meal and fermented soybean meal had highest apparent digestibility coefficients (ADCs) of dry matter, crude protein and gross energy among ingredients tested, ranged from 50.4% to 60.9% for dry matter, from 64.6% to 88.4% for crude protein and from 57.9% to 79.0% for gross energy. The apparent digestibility coefficients of dry matter ranged from 61.0% to 66.9% for animal products and 50.4% to 60.7% for plant products. For crude protein, apparent digestibility coefficients of protein exceeding 80% were observed for white fish meal, brown fish meal, meat meal and fermented soybean meal, and the apparent digestibility coefficients of protein in rapeseed meal were the lowest among all the treatments. Lipids from both animal and plant feedstuffs were poorly digested by loach, ranging from 64.0% to 77.6%. The apparent digestibility coefficients of energy were similar to those of dry matter and protein, and the highest and lowest ADCs of energy were found in WFM and RM, respectively. The loach used dietary phosphorus from the animal feedstuffs more efficiently than from plant feedstuffs (soybean meal and rapeseed meal), with ADC‐values ranging from 42.3% to 53.1% and from 25.1% to 32.7%, respectively. For the animal products, the availabilities of amino acids in white fish meal and brown fish meal were higher than that in meat meal, expect for Met, Asp, Pro, Gly, and Cys. Among all the plant products, the availabilities of amino acids in fermented soybean meal were higher than in soybean meal and rapeseed meal, and thus had a greater potential to be used as a dietary replacement of fish meal in loach diets.     

Physiological responses and HSP70 mRNA expression of GIFT strain of Nile tilapia (Oreochromis niloticus) under cold stress

An investigation on the physiological responses and HSP70 expression under cold stress was conducted on Genetically Improved Farmed Tilapia (GIFT) strain of Nile tilapia (Oreochromis niloticus). Tilapia were acclimated at 28°C as control and then the water temperature was reduced from 28°C to 15°C at a rate of 1°C h^?1, and serum biochemical indices, antioxidant enzymes and expression of HSP70 mRNA were analysed on days 0, 0.5, 1, 2, 3 and 5 after exposure to 15°C. The concentration of serum K, Na, Cl and Ca concentration showed instability during cold stress. Glucose rapidly increased on day 0 followed by a declining trend. Triglyceride, cholesterol, low density lipoprotein‐cholesterol signifi‐cantly decreased and high density lipoprotein‐cholesterol showed instability during cold stress. Aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase activities were prominently elevated under cold stress. Superoxide dismutase and catalase activities showed a remarkable rise on day 0.5 under cold stress, and gradually decreased thereafter. HSP70 mRNA level significantly increased both in liver and muscle under cold stress, especially on days 0.5 and 1. These results suggest that cold influences several physiological responses of tilapia, and the cold resistance and cold tolerance of tilapia will benefit from the enhancement of antioxidant enzymes activities and upregulated HSP70 mRNA expression.     

Artificial fertilization and generating families for a selective breeding programme of large yellow croaker ( Larimichthys crocea )

Large yellow croaker is an important marine aquaculture species in China. The aim was to determine an appropriate protocol of artificial fertilization for family construction in the breeding programme based on two trials. In trial 1, luteinizing hormone-releasing hormone A3 (LHRHA3) was injected once, with a dosage of 2 μg/kg for females and 1 μg/kg for males. The latency time was in the range of 30–34 h. The maturation stage was checked by extracting a few eggs with a Pasteur pipette. The fertilization rate and hatching rate were 27 and 52%, respectively. The percentage of females with spawning difficulties was 30%. In trial 2, the females were injected LHRHA3 twice: with a first dose of 0.8 μg/kg and a second dose of 2 μg/kg, at an interval of 10 h, whereas the males were still injected once. The latency time was in the range of 29.5–35 h, determined by only observing courtship behaviour of males. The females with spawning difficulties decreased to 10%, and the fertilization rate and hatching rate also improved to 41 and 62%, respectively.     

经验对欧洲舌齿鲈幼鱼行为及其关联性指标的影响

学习和信息传递是鱼类认知过程中的重要内容.本研究设计了特定实验装置,通过2个实验测定了欧洲舌齿鲈(Dicentrarchus labrax)幼鱼在有/无有经验个体条件下完成任务的时间和行为表现.实验装置呈"L"型,有3个PVC材质构建的60cmx60cm的实验区域,2个相邻区域之间用内径为12 cm的圆柱体通道连通(即...     

环境因子对海月水母生活史关键阶段的影响

近年来,大型胶质水母类,尤其是钵水母纲生物在全球沿岸海域大量出现,引发了一系列生态和经济问题[1-6],如毁坏网具[7-8],蛰伤游泳者[9-10],在养殖池塘中泛滥成灾等[11-12].同时,水母聚集会堵塞核电站冷源取水口,造成发电机组甚至反应堆异常停止,给核电站正常运行带来了极大风险.因此,关于致灾水母的研究已经成...     

盐度骤变对金钱鱼幼鱼鳃线粒体丰富细胞形态结构的影响

文章采用显微技术研究了盐度骤降(20盐度组投入5盐度组)、盐度骤升(20盐度组投入35盐度组)胁迫下,金钱鱼(Scatophagus argus)幼鱼鳃线粒体丰富细胞(Mitochondria-rich cells,MRCs)形态结构的变化.结果显示,低盐胁迫3 h MRCs长径[(9.517±1.390)μm]和短径...     

饲料脂肪水平对江黄颡鱼幼鱼生长性能的影响

研究了饲料中脂肪水平对江黄颡鱼幼鱼(平均体重0.44g)生长性能的影响。实验共设5个水平组,饲料脂肪水平分别为3.77%,4.82%,7.29%,8.37%,9.87%。每组20尾,3个平行,饲养66d。结果显示:随着饲料脂肪水平的升高,江黄颡鱼幼鱼的饲料系数呈上升趋势,蛋白质效率则呈下降趋势,增重率和特定生长率呈抛物线变化,但饲料系数和蛋白质效率差异不显著(P0.05),增重率和特定生长率差异显著(P0.05)。江黄颡鱼幼鱼肝脏中脂肪的蓄积量随饲料中脂肪水平的增加而增加。综合各项指标并分析增重率、特定生长率与脂肪水平的回归性关系,可以推测江黄颡鱼幼鱼期的饲料脂肪水平应该维持在7.59%~7.65%。     

Effect of Chitosan on Intestinal Bacteria of Allogynogenetic Crucian Carp,Carassius auratus gibelio,as Depicted by polymerase chain reaction‐denaturing Gradient Gel Electrophoresis

A 16S rDNA‐based polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) method was applied to detect intestinal bacterial communities of juvenile allogynogenetic crucian carp, Carassius auratus gibelio, fed with chitosan‐containing diet. This is the first time to use the molecular method to analyze the bacterial communities in the allogynogenetic crucian carp intestine. The DGGE profile with universal bacterial primers revealed simple communities in all treatment groups. Sequencing and phylogenetic analysis of excised DGGE bands showed that the dominant bacteria belonged to class γ‐Proteobacteria and Fusobacteria. The relative abundance and diversity of detected bacteria suggested that 0.5 and 0.75% of chitosan in diet were optimum for juvenile allogynogenetic crucian carp. As in these concentrations, some detected pathogen bacteria either disappeared or decreased. However, the DGGE profile with Aeromonas‐specific primers showed a similar composition among all treatment groups, which suggested that Aeromonas was one of relative stable bacteria components in the intestine of juvenile allogynogenetic crucian carp.     

水产养殖中亚硝酸盐毒性影响及处理的研究进展

亚硝酸盐是水产养殖系统中常见的污染物,也是影响水体生态环境的重要因素。养殖水体中亚硝酸盐浓度超标会造成鱼类、软体动物、甲壳类等水生动物中毒甚至死亡。本文论述了亚硝酸盐的产生机理、毒性与危害以及治理方法等,以期为安全有效地降解亚硝酸盐、提高水产养殖产业的经济效益、修复生态环境的平衡提供科学依据。     

聚维酮碘对中华绒鳌蟹蟹种急性毒性实验和概率回归分析

本实验为掌握聚维酮碘对中华绒鳌蟹蟹种的半致死剂量(LD50)。通过预实验,得到实验剂量的上限剂量对数值(Xk)和下限剂量对数值(Xi),实验组间距(d),再确定实验组药物浓度。实验设1个对照组,7个实验组药物浓度分别为15.85,19.50,23.99,29.51,36.31,44.67和54.95mg/L。每个实验组放置雌、雄蟹蟹种各10只,平均体重(5.95±0.48)g。以一次性给药方式,观察和记录24h和48h实验蟹种的死亡情况。实验数据采用SAS统计软件中概率单位程序进行概率回归分析。实验结果显示,7个实验组聚维酮碘对中华绒鳌蟹蟹种24h急性毒性试验死亡率分别为0、0、0.15%、0.35%、0.85%、0.95%、100.0%、100.0%。直线回归方程:Y=-16.104 1+11.519 2log(Dose),R2=0.897 4(P>0.8)。24h半致死剂量(LD50)为25.004 86mg/L,95%可置信区间23.313 96~26.806 31mg/L。48h对照组和实验组实验蟹种在24h基础上均无死亡。