转盘式对虾开背工艺分析与参数优化

针对目前对虾开背环节工艺不完善、实际应用装备缺乏等问题,以中型南美白对虾为研究对象,探究了对虾开背关键工艺方法,建立了对虾开背过程力学模型,获得影响开背效果主要因素为刀具角度、加工中心盘转速和刀具安置距离;采用单因素试验研究和分析了各因素对开背成功率、虾仁损伤率、虾线裸露成功率和感官评分值的影响,确定影响因素最佳区间为：刀具角度20°~60°、加工中心盘转速10~40r/min和刀具安置距离9~11mm;利用Design-Expert软件进行多因素响应面试验研究分析,并采用多目标优化方法,得到最优参数组合为：刀具角度43.838°、加工中心盘转速28.391r/min、刀具安置距离9.801mm时,开背成功率为99.161%、虾仁损伤率为2.825%、虾线裸露成功率为90.727%、感官评分值为86.944。验证试验结果表明：针对中型南美白对虾,当刀具角度45°、加工中心盘转速28r/min、刀具安置距离9.8mm时,开背成功率为98.89%、虾仁损伤率为3.33%、虾线裸露成功率为87.78%、感官评分值为85.33,与理论优化值的绝对误差均较小,优化后的对虾开背装置性能满足作业要求。研究可为对虾开背工序装置设计和参数选择提供理论基础和科学依据。     

A review on the diseases of freshwater prawns with special focus on white tail disease of Macrobrachium rosenbergii

Freshwater prawns, particularly, the Giant Freshwater prawn Macrobrachium rosenbergii, are one of the most economically important farmed species in the world. Faced with increasing disease problems in penaeid shrimp culture, farmers turned to freshwater prawn farming. Freshwater prawns were considered relatively less susceptible to diseases. However, with intensification of culture and increased world trade of the farmed species, emerging diseases are beginning to constitute an increasingly serious health problem in freshwater prawn culture. This article is a review of the important diseases reported in freshwater prawns, with particular emphasis on the white tail disease of M. rosenbergii as it is the most important disease recorded to date and also the most well studied among the diseases of freshwater prawns. Steps to be taken for proper health management in the farming of this species is also touched upon.     

Macro and Micro Mineral Levels in the Tissues of Menhaden Fish

Various tissues of menhaden fish were analyzed for macro and micro minerals. Tissues selected were gill, heart, intestine, kidney, liver, muscle, spleen, and stomach. Phosphorus, calcium, magnesium, sodium, manganese, and zinc were found to be most concentrated in the gill. Potassium, iron, and boron were least concentrated in the gill. Liver contained the highest concentration of copper, selenium and boron. The stomach was the highest in potassium and lowest in phosphorus. Sodium and selenium concentrations were lowest in the muscle. Mercury concentrations were approximately 2 mg/g dry matter in all tissues     

鲈与中国对虾混养试验

１９９５、１９９６年进行鲈与中国对虾混养试验，利用鲈摄食病虾及小型糠虾类，阻断病毒传播，推迟了对虾发病，试验池产量，效益成活率均高于对照池。     

广东对虾产业竞争力分析

经过30多年的发展,广东已经成为中国最大的对虾生产和出口地区。广东既具有对虾生产和出口方面的绝对优势,又具有资源和竞争力等方面的相对比较优势。面对国内外同业的竞争,增加高附加值产品、促进出口市场多元化是增强广东对虾竞争优势的关键。     

Utilization of monounsaturated fatty acid (18:1n-9, oleic acid) by freshwater prawn Macrobrachium rosenbergii (de Man) juveniles

The utilization of oleic acid as an energy source and the effects of oleic acid levels and/or dietary soy bean lecithin (SBL) on oleic acid utilization, growth and survival, and lipid class and fatty acid compositions of freshwater prawn, Macrobrachium rosenbergii (de Man), juveniles were determined.
Increase in levels of dietary oleic acid from 10 to 80 g kg⁻¹ significantly ( P ≤ 0.05) reduced growth, survival and feed conversion efficiency of M. rosenbergii juveniles during the 40-day feeding period. Inclusion of 20 g kg⁻¹ SBL had no significant effect ( P ≥ 0.05) on growth and survival, nor was there any interactive effect between dietary SBL and oleic acid levels.
Body fatty acid profile of prawns reflected dietary fatty acid quantity. The fatty acid composition of prawns fed diets containing 80 g kg⁻¹ oleic acid had tremendously high proportions of oleic acid. Polar lipids, mostly phosphatidylcholine (PC), constituted the bulk of the extracted total lipids. Prawns fed with SBL had significantly ( P ≥ 0.05) higher PC content.
Oleic acid was metabolized for energy by M. rosenbergii juveniles at the same rate regardless of dietary level of SBL and/or oleic acid. Expired ¹⁴CO₂ accounted for half of the ingested radioactivity 48 h after feeding with labelled diets. No significant difference in the amount of ¹⁴CO₂ expired by prawns fed the labelled test diets was found. Per cent radioactivity ingested and absorbed into the body was also not significantly different in prawns of the different dietary treatments.     

靖海湾和五垒岛湾放流增殖中国对虾的回游与分布

用烧结法标志中国对虾，在靖海湾和五垒岛湾进行增殖放流，研究其回游与分布规律。重捕资料表明，６月中旬幼对虾对湾内河口浅水区生活随体长增长，逐步向深水扩散；８月上，中旬主群陆续游向湾外，按地形走向向西南回游，部分向东或东南；１０月份回游对湾外水域的对虾有向东，东北或东南回游的现象。