大菱鲆幼鱼对几种蛋白质源中营养物质的表观消化率及膨化处理对其产生的影响

本试验旨在研究大菱鲆(Scophthalmus maximus L.)对秘鲁红鱼粉、豆粕、葵花粕和玉米蛋白粉中干物质、粗蛋白质、氨基酸和总能的表观消化率,以及膨化处理对其产生的影响。试验饲料由70%基础饲料和30%待测蛋白质源组成,并添加0.1%的三氧化二钇(Y2O3)作为外源指示剂,将其分别制作成正常颗粒料和膨化颗粒料。将平均体重为(8.98±0.01)g的大菱鲆幼鱼随机分成10组,每组3个重复,每个重复40尾鱼,按照不同处理分别投喂相应饲料,喂养2周后采用后肠挤压法收集粪便样品至第6周。结果表明:大菱鲆幼鱼对4种蛋白质源中干物质、粗蛋白质、总氨基酸和总能的表观消化率分别为22.33%~65.50%、48.97%~85.28%、47.70%~84.14%和44.50%~81.16%。其中,秘鲁红鱼粉的各营养物质的表观消化率均显著高于3种植物蛋白质源(P0.05);3种植物蛋白质源中以豆粕中粗蛋白质的表观消化率最高,葵花粕次之,玉米蛋白粉最低;各待测蛋白质源中总氨基酸表观消化率的变化趋势与粗蛋白质表观消化率基本一致。经膨化处理后,大菱鲆对4种蛋白质源中营养物质的表观消化率均得到改善,尤其是3种植物蛋白质源,效果显著(P0.05),膨化处理后4种蛋白质源中干物质、粗蛋白质、总氨基酸和总能的表观消化率分别为24.26%~70.87%、57.20%~85.33%、68.27%~87.09%和49.23%~84.35%。由此得出,膨化处理能够提高大菱鲆幼鱼对秘鲁红鱼粉、豆粕、葵花粕和玉米蛋白粉中营养物质的表观消化率。     

中国大菱鲆引进群体三代选育之后的收获体重遗传进展评估

评估了大菱鲆3个世代选育后（G0、G1、G2和G3）收获体重的遗传参数及遗传进展,分析数据来自于4个世代构建的总共590个家系的12980尾个体。G0、G1、G2和G3的收获体重性状估计遗传力分别为0.19±0.08、0.18±0.09、0.51±0.09和0.29±0.16,跨世代的遗传力为0.16±0.03。根据每一世代所有个体和留作亲鱼个体的平均估计育种值计算了选择差,在G0中为45.6 g,在G1中为13.1 g,而在G2代是 -27.9 g,每代平均10.3 g。遗传进展分别为10.2、37.4、0.3 g,分别相当于2.06%、8.76%、0.04%。经过3个世代选育后的收获体重性状的累积遗传进展为10.86%,平均每代3.56%,表明大菱鲆体重性状的选育工作总体上是成功的。     

我国大菱鲆产业价值链实证研究

随着规模的扩大,大菱鲆养殖产业逐渐从高利时代步入常利时代,各种深层次问题开始显现,产业升级已势在必行.着眼于产业内部,进行产业链优化整合可以提高产业运行效率、总利润和各环节的福利,是实现产业升级的切入点.基于实证调研,分析了我国大菱鲆产业链构成及产业价值链,初步研究结果表明,各环节价值增值量依次为:餐饮＞养殖＞育苗＞综...     

Fishmeal replacement by mixed plant proteins and maggot meal on growth performance,target of rapamycin signalling and metabolism in juvenile turbot (Scophthalmus maximus L.)

Fishmeal could only be replaced by plant proteins at limited levels in aquafeeds, especially for carnivorous fish. In this study, an experiment was designed to evaluate the possibility of improving the utilization of plant proteins by maggot meal supplementation in turbot diet. Five diets were formulated: a reference diet (FM) containing 63% fishmeal and four experimental diets (35(0%), 35(3%), 40(0%), 40(3%)) in which fishmeal was substituted at different levels by plant proteins with 0–3% maggot meal. Turbot (4.90 ± 0.03 g) was fed with these diets for 9 weeks. Fishmeal was successfully replaced by plant proteins in turbot diet without growth reduction at 35% but not 40%. However, maggot supplementation (3%) at 40% plant protein replacement level achieved comparable growth performance with that of fishmeal. Maggot meal supplementation improved apparent digestibility coefficients, plasma hydroxyproline levels, intestine trypsin activities and activated target of rapamycin (TOR) signalling, all of which were decreased or down‐regulated after high plant protein replacement. Therefore, this study demonstrated maggot meal, a potential valuable protein source for turbot.     

Estimation of genetic parameters for early growth trait of turbot (Scophthalmus maximus L.) using molecular relatedness

In this study, a data set of 1140 progenies from 19 families that were composed of 13 half‐sib and six full‐sib families was used in the estimation of the genetic parameters of weight for juvenile turbot at 100 days post hatch. Sixty progenies were randomly selected from each family, and 20 of these individuals were genotyped at 12 microsatellite loci. Two sorts of relatedness, including pedigree relatedness (PR) from a complete pedigree and average molecular relatedness (AMR) from molecular markers, were compared to explore the feasibility of AMR in selective breeding when only parents were known. Two different animal models, Model 1 and Model 2 which were without and with the addition of maternal and common environmental effects, respectively, were used to estimate the variance component and breeding values for weight using restricted maximum likelihood (REML) method. Thereafter, cross‐validation was applied to investigate predictive ability of model and accuracy of breeding values. Pearson correlation analysis showed that AMR was highly correlated (0.91) with PR. According to conditional Akaike Information Criterion, the best models for AMR and PR methods were Model 2 and Model 1 respectively. Heritability estimates from AMR and PR methods based on their best models were 0.19 (±0.06) and 0.66 (±0.17). Cross‐validation showed that AMR was comparable to PR in terms of predictive abilities and accuracies of breeding values based on the same model. This study therefore suggests that the AMR can be applied as alternative of PR when only parents were known.     

Inorganic nitrogen addition in a semi‐intensive turbot larval aquaculture system: effects on phytoplankton and zooplankton composition

A nitrogen manipulation experiment was conducted in a semi‐intensive outdoor system where turbot larvae feed on copepods. Nitrogen addition is hypothesized to stimulate a cascade reaction increasing phytoplankton biomass, copepods’ productivity and larval fish survival. Triplicates were established for three treatments: a control with no additional nitrogen, a pulsed dose where nitrogen was added in three doses over time and a full dose where all nitrogen, equal to the total of the pulse dose treatment, was added initially. In the control, chlorophyll a averaged 3.3 ± 1.5 μg L^?1 and phytoplankton was dominated by diatoms, while the pulsed and full dose treatments showed chlorophyll a at 28.6 ± 9.9 and 47.7 ± 10.0 μg L^?1, respectively, with dinoflagellates as the main phytoplankton group. Due to photosynthesis, pH increased >9 in both the nitrogen treatments compared to the control (8.5). Potential toxic dinoflagellates, including Alexandrium pseudogonyaulax and Prorocentrum spp., became dominant in the nitrogen treatments and might have arrested zooplankton recruitment. Laboratory experiments with a toxic strain of A. pseudogonyaulax proved that Acartia tonsa reproduction and naupliar survival were affected negatively at realistic fish tank concentrations of 100 and 20 cells mL^?1, respectively. Compared to the control, pulsed and full dose treatments reached higher copepod biomass and showed a shift over time in species composition from Centropages hamatus to Acartia spp. However, high pH levels and dinoflagellate blooms had a negative effect on larval fish survival, suggesting management improvements on water quality and separation between copepods and fish production tanks.     

循环水养殖条件下水温对大菱鲆氨氮排泄、转氨酶及免疫因子的影响

在高密度工业化封闭循环海水养殖条件下（养殖密度为14?2±0?48 kg／m2）,选取大菱鲆（371?68±43?15 g）360尾,随机均分4组,设置4个水温梯度14℃、16℃、18℃和21℃,旨在探寻水温对大菱鲆氨氮排泄、转氨酶及血清免疫因子的影响,试验期为56 d。结果表明：（1）养殖水体总氨氮浓度随水温升高呈先升后降,18℃时总氨氮浓度极显著高于14℃、21℃时;大菱鲆氨氮排泄率随水温升高而升高,且二者呈指数关系。（2）大菱鲆肝脏GPT、GOT活力随水温升高呈先升后降,均在18℃达最大值;而血清两种指标变化趋势与之相反,均在21℃达最大值。（3）血清LZM、SOD活力及皮质醇含量均随水温升高呈先升后降,均在18℃达最大值;血氨含量则逐渐下降,14℃时极显著高于18℃、21℃时;鳃丝Na＋?K＋?ATPase活力随水温升高而升高,但组间差异不显著。综上,封闭循环水养殖大菱鲆的适宜水温为16～18℃。     

Pathology of Edwardsiella tarda infection in turbot, Scophthalmus maximus (L.)

Macroscopic and histopathological changes in cultured turbot, Scophthalmus maximus (L.), in Spain caused by infection with Edwardsiella tarda are described. Eye tumefaction, inflammation, haemorrhages, ascites and the presence of a purulent fluid were the main macroscopic lesions observed. Histopathological lesions were found in the kidney, spleen and liver. In the kidney and spleen these were characterized by a severe apostematous inflammatory reaction, with a large number of abscesses. The liver was affected to a lesser degree and only some phagocytes loaded with bacteria were observed. Ultrastructural observations indicated that macrophages were the main cell type implicated in the inflammatory response. Most of the bacteria observed within the phagocyte cytoplasm showed no degenerative changes and some were dividing. Degenerative changes observed in macrophages indicate their failure in preventing the infection.     

Characterization of Edwardsiella tarda strains isolated from turbot, Psetta maxima (L.)

The biochemical, serological and molecular characteristics of a group of 21 Edwardsiella tarda strains isolated from turbot, Psetta maxima, in two different areas of Europe were analysed and compared with a total of 13 strains of this bacterial species with different geographical and host origins. All the turbot isolates were biochemically identical to the E. tarda strains included as reference. The use of different techniques including microagglutination, dot blot and Western blot of lipopolysaccharides allowed us to determine that all the turbot isolates constitute an homogeneous and distinctive serological group. Genetic analysis by randomly amplified polymorphic DNA (RAPD) analysis demonstrated that although the E. tarda strains from turbot were compiled in a unique group using the primers P3 and P6, two clonal lineages could be detected when oligonucleotides P4 and P5 were employed.