鱼类腐败菌不同生长动力学温度模型的可靠性评价和比较

探讨和比较了Arrhenius方程和Belehradek方程两种腐败菌生长动力学温度模型预测鱼鲜度和货架期的可靠性。结果表明，两种温度模型都能很好地预测罗非鱼中假单胞菌的生长动态和预报货架期，通过假单胞菌生长动力学模型的预测值，与罗非鱼中假单胞菌生长的实测值比较，偏差度在0．95～1．01之间，准确度在1．02～1．06之间，两种温度模型相比，Belehradek温度模型的可靠性更好。罗非鱼在3和8℃贮藏中货架期实测值与利用Arrhenius方程和Belehradek方程建立的假单胞菌生长动力学温度模型求得的预测值的比较，Arrhenius温度模型预测值和实测值的相对误差分别为11．8％和8．00％，Belehradek温度模型预测值和实测值的相对误差分别为3．47％和一7．91％，两种温度模型相比，Belehradek温度模型的结果更为理想。     

Transgenic Nile tilapia (Oreochromis niloticus) over-expressing growth hormone show reduced ammonia excretion

The growth of aquaculture has negatively affected the environment due to the high levels of nitrogen excreted by farmed fish. Here we propose that modifying the nitrogen metabolism of the fish themselves using transgenic technology might solve the pollution problem. Growth hormone (GH) is known to increase protein retention and absorption, and is thought to reduce ammonia excretion. Thus, we produced transgenic Nile tilapia (Oreochromis niloticus) that over-expressed the GH gene throughout their bodies. Our findings showed that the food-conversion efficiency of the transgenic fish was 35% higher than that of their non-transgenic siblings. The rearing period required for the transgenic fish to reach a body weight of 20 g was about 75% of that required for non-transgenic fish that were fed the same type and quantity of food. The total amount of ammonium-nitrogen excreted by the transgenic fish was about 69% of that excreted by the wild-type fish over their lifetime. These results suggest that our transgenic approach has the potential to reduce the amount of nitrogen pollution caused by farmed fish. This strategy is a promising option for making aquaculture more ‘eco-friendly’.     

积温和放养规格对网箱养殖罗非鱼的影响

利用大秋房水库网箱养罗罗非鱼的６年生产记录，以放养规格以及每天大于１５℃、大于２０℃的积温和天数作为自变量、以个体增肉倍数、饵料系数作为变量，进行一元和二无回归分析。结果发现：每天大于１５℃的积温和天数与增肉倍数相关最显著；第天大于１５℃的天数和放养规格与饵料系数相关也较显著。     

影响罗非鱼国内市场消费主要因素的探讨

2012年我国罗非鱼养殖产量为144万t,占世界罗非鱼养殖总产量的40%左右。我国60%罗非鱼养殖产量用于加工出口,罗非鱼产业可持续发展完全依赖于加工产品的国际竞争力。近年来受国际市场和金融危机等因素的影响,罗非鱼出口量有下降的趋势,严重影响了我国罗非鱼产业的健康发展。如何开拓罗非鱼国内消费市场,减少产业国际竞争压力是当前亟待解决的研究课题。为了深入研究罗非鱼国内消费市场、提出行之有效的政策建议,从消费者、营销、产业和社会等方面探讨了影响罗非鱼国内市场消费的主要因素。     

辣木叶粉在鱼饲料中的应用研究

[目的]辣木是一种尚未充分开发利用的树种。辣木绿色物质部分产量高,营养丰富,开发其资源可弥补传统蛋白质饲料源的短缺。探讨以辣木叶粉作为配方主要蛋白质原料之一和组成全价颗粒鱼饲料配方的可行性。[方法]以15%的辣木叶粉替代8.7%的次粉和6.3%的菜籽粕构成全价颗粒饲料配方,研究辣木叶粉对鱼生长和饲料利用的影响。[结果]试验组罗非鱼平均鱼体终重和平均增重均比对照组明显提高,而饲料系数则比对照组显著降低。试验组鱼存活率比对照组略低。[结论]该研究可为水产动物营养研究和进一步研制高效、廉价的温水性鱼人工配合饲料提供基础资料。     

Competition and niche partitioning in a floodplain ecosystem: a cladoceran community squeezed between fish and invertebrate predation

Seasonal floodplains occasionally comprise highly productive zooplankton communities which are exposed to rapid shifts in predator regimes, also between vertebrate and invertebrate predators.We recorded the impact of two co-occurring zooplankton predators, the notonectid Anisops sardea and 0+ fish fry of Tilapia rendalli (max gape size 1 mm), on a cladoceran community dominated by Ceriodaphnia reticulata (0.25–0.78 mm), Daphnia laevis (0.6– 1.8 mm) and Scapholeberis kingi (0.27–0.8 mm). Both predators strongly reduced abundance of all prey species, yet with a striking size-selective effect for Daphnia prey only, where fish showed a strong preference for small individuals, while Anisops preferred large Daphnia individuals. This contrasts with the general view of size selection in invertebrate versus vertebrate predators, but is logically caused by the feeding mode of the notonectid, and the gape size limitation of the fish fry. The two predators also showed a dietary niche differentiation in terms of both prey selection and habitat choice. T. rendalli fed preferably on small species and size classes, whereas predation from A. sardea concentrated on large prey. Competitive interference was indicated when feeding on Ceriodaphnia, and niche partitioning when feeding on the two other species. The predatory pattern suggests long-lasting coexistence in the system.     

罗非鱼鱼排蛋白酶解液美拉德反应生香工艺优化研究

为了对罗非鱼鱼排蛋白酶解液美拉德反应生香工艺进行研究,以风味总体接受性为指标,对反应温度、时间、pH值、还原糖添加量4个因素采用响应面法进行多元回归拟合,优化美拉德反应条件,并用HPLC、GC-MS对反应产物进行分析。结果表明：美拉德反应最佳工艺条件为反应时间57 min,反应温度111℃,pH 6.0,还原糖（葡萄糖:木糖=2:1）添加量2.0%;反应产物中有机酸含量较反应前酶解液中有机酸含量丰富,核酸关联物较反应前多了呈味的鸟苷酸;反应产物中挥发性成分包括68种风味化合物,分别是醇类6种、醛类7种、酮类5种、芳香族7种、酯类11种、呋喃8种、吡嗪9种、吡咯1种、烃类7种、酸类5种和含硫化合物2种。罗非鱼鱼排蛋白酶解液经美拉德反应,产物呈透明红褐色,具有独特的鱼香味（香味浓郁）。     

高活性荚膜红假单胞菌分离鉴定及应用

[目的]分离筛选出高活性荚膜红假单胞菌,并作为水质净化剂和饲料添加剂应用于鱼苗生产培育中,以促进广西水产养殖业的健康发展.[方法]采用平板稀释涂布法从广西本地高产对虾塘底泥中分离筛选出活性较高的菌株,然后从形态学特征、生理生化特性及参照《伯杰氏细菌鉴定手册》等鉴定菌株,并将其应用于罗非鱼鱼苗培育试验.[结果]分离筛选出的光合细菌(菌株NC01)菌体卵圆形、革兰氏染色阴性,培养的菌落圆形、红色、边缘整齐、表面光滑、湿润,菌体大小0.6~0.9 μm×1.5~2.5 μm;在光照厌氧条件下培养,繁殖速度较快,在扩大培养基中培养液颜色由浅红色逐渐变成紫红色;根据《伯杰氏细菌鉴定手册》鉴定为荚膜红假单胞菌.将其应用于罗非鱼鱼苗生产培育,发现荚膜红假单胞菌能稳定水体pH,显著降低水体氨氮、亚硝酸盐、化学需氧量(COD)含量,降幅分别为36.69%、27.47%、45.89%;鱼苗体长增加43.66%、体重增加44.79%、成活率提高10.60%(绝对值).[结论]从广西本地高产对虾塘底泥中分离筛选出的荚膜红假单胞菌,其生理生化特性及商品性能良好,且在罗非鱼鱼苗培育中效果显著,生产上可以大批量生产并推广应用于水产养殖.     

不同水平饲料镉对罗非鱼生长性能和肠道消化酶活性影响的研究

为研究不同水平饲料镉对罗非鱼生长性能和肠道消化酶活性的影响。将300尾罗非鱼随机分为5个处理,饲料镉添加水平分别为0、50、100、200、400 mg/kg,试验期为8周。结果表明：与对照组相比,饲料镉添加组增重率和特定生长率均逐渐降低,200、400 mg/kg添加水平组显著降低(P＜0.05);各处理组之间摄食率、饲料系数和成活率均无显著差异(P＞0.05)。饲料镉添加水平组罗非鱼肠道淀粉酶活性和蛋白酶活性均显著低于对照组(P＜0.05),当饲料中添加50 mg/kg镉时,罗非鱼肠道淀粉酶活性和蛋白酶活性即可显著降低(P＜0.05);罗非鱼脂肪酶活性仅在饲料镉添加水平400 mg/kg时显著低于对照组(P＜0.05),其余各处理组间差异不显著(P＞0.05)。表明罗非鱼对饲料镉耐受程度较高,饲料中镉达到200 mg/kg时,才可显著影响罗非鱼增重率和特定生长率。饲料中不同水平镉对罗非鱼肠道消化酶活性具有不同程度的抑制作用,饲料中添加50 mg/kg镉时即可显著降低肠道淀粉酶和蛋白酶的活性,肠道脂肪酶活性仅在400 mg/kg时显著降低。     

Impact of Sump Tank Size on Growth,Survival, and Production of Marron,Cherax tenuimanus,in an Intensive System

Juvenile marron, Cherax tenuimanus were cultured in an intensive crayfish culture system for a period of six months to study the effects of sump tank size on crayfish growth, survival, and production. Water volume in the large sump system was 2750 L and in the small sump tank system was 500 L. Crayfish were held in individual compartments (surface area 320 cm², depth 10 cm) and fed with commercial pellets (30% protein; 3-5% body weight per week). Specific growth rate (SGR) was 0.75%/day in the large sump system and 0.68%/day in the small sump system; survival was 83% in the large sump system and 71% in the small sump system; and biomass roduction (B) was 239 g/m² in the large sump system and 158 g/m² in the small sump system. These values were all higher (P < 0.05) in the large sump system. The results suggest that crayfish production could be improved by using large sump tanks in recirculating intensive crayfish culture systems.