不同饵料对黑鲍幼鲍生长及存活的影响

本实验研究了裂片石莼(Ulva fasciata)、龙须菜(Gracilaria lemaneiformis)、海带(Laminaria japonica)、细基江蓠繁枝变种(Gracilaria tenuistipitata)、舌状蜈蚣藻(Grateloupia livida)和人工配合饲料6种饵料对黑鲍[(Haliotis discus hannai Ino)(♀)×(Haliotis discus discus Ino)(♂)]幼鲍存活和生长的影响.将6种饵料随机分成6组,每组3个重复,每个重复饲养黑鲍20只.实验幼鲍的初始体长、体质量分别为(12.29±0.03)mm、(0.223±0.002)g,实验为期35 d.实验结果如下:(1)不同饵料对幼鲍的存活率有显著影响(P＜0.05),且由大到小依次为海带组、人工配合饲料组、龙须菜组、蜈蚣藻组、江蓠组和石莼组.其中海带组、人工配合饲料组的存活率显著大于其他海藻组(P＜0.05);(2)不同饵料对幼鲍的生长有显著影响(P＜0.05),6种饵料组的幼鲍的特定生长率(SGR)由大到小依次为人工配合饲料组、海带组、江蓠组、石莼组、龙须菜组和蜈蚣藻组.其中人工配合饲料组、海带组的SGR显著大于其他饵料组(P＜0.05).壳长增长率、湿重增重率、干重增重率亦呈现相似趋势.实验结束时,蜈蚣藻组的体质量呈现负增长;(3)幼鲍对不同饵料的转化效率存在显著差异(P＜0.05),幼鲍对人工配合饲料的转化效率是最大.实验结果表明人工配合饲料和海带是黑鲍养殖生产上最佳的选择.     

驯化摄食对黑鲍饵料选择性的影响研究

研究了黑鲍(Haliotis discus hannai♀×H·discusdiscus♂)对裂片石莼(Ulva faxciata)、龙须菜(Gracilaria lemaneiformis)、海带(Laminaria japonica)、细基江蓠繁枝变种(G·tenuistipitata)、舌状蜈蚣藻(Grateloupia livi-da)和人工配合饲料6种饵料的选择性,继而通过实验研究了强制摄食驯化对黑鲍饵料选择性的影响。实验发现,在无饵料强制驯化的状态下,黑鲍对几种实验海藻的选择性依次为海带>石莼>江蓠>龙须菜>蜈蚣藻;在用单一饵料强制驯化7d后,黑鲍对几种实验海藻的选择性依次为海带>江蓠>石莼>龙须菜>蜈蚣藻。而黑鲍对人工配合饲料的摄食存在随机性,没有一定的规律。研究表明,海带是黑鲍最喜食的饵料,前期摄食驯化对其饵料选择性没有显著的影响。     

几种陆、海生植物源对仿刺参幼参生长指标的影响

使用鼠尾藻、亨氏马尾藻、石莼、浒苔、马齿苋、羊栖菜、海带等7种植物源单独投喂仿刺参幼参,一种商品饲料作为对照组,各试验设3个平行,每平行20头幼参(体质量2.5~3.5g/头),试验周期60d,之后通过对比体长、特定生长率、质量平均增加率、蛋白质表观消化率、存活率、饲养水质等指标,得出可能适宜作为幼参人工配合饵料的配料成分。试验结果表明,以体长为考核指标,各种植物源对其影响依次为:马尾藻海带200目浒苔粉鼠尾藻马齿苋石莼粉400目浒苔粉羊栖菜添加海泥400目浒苔,部分组别之间差异极显著(P0.01);以幼参特定生长率、质量平均增加率、表观消化率、饵料系数为考核指标时,鼠尾藻、马尾藻、石莼、浒苔各项数值优于其他植物源,差异显著(P0.05);马尾藻的蛋白质表观消化率高于其他植物源,羊栖菜的表观消化率值最低;浒苔、石莼、鼠尾藻、马尾藻较其他植物源更有利于幼参生长,可作为幼参人工配合饲料组分。     

不同光照强度对刺参幼参生长的影响

采用室内受控的实验方法研究了不同光照强度对刺参幼参生长的影响。实验设暗光、微强光、强光3个光照处理,同时每个光照处理组分别投喂两种饵料(人工配合饲料、人工配合饲料加底栖硅藻)。研究结果表明,不同光照强度下,幼参的生长差异显著(P<0.05),每种饵料处理下强光处理组幼参的特定生长率和日增重明显高于暗光处理组,而相同光照强度下两种饵料处理对幼参生长的影响差异不显著(P>0.05)。3个光照处理下幼参的特定生长率平均分别为0.26%、0.63%、0.98%/d,日增重为0.53、1.39、2.26 g/d。     

人工饲料和浒苔饲喂对点篮子鱼幼鱼生长性能和消化酶活性影响

以点篮子鱼(Siganus guttatus)幼鱼为研究对象,分别使用人工饲料和浒苔(Enteromorpha prolifra)饲喂点篮子幼鱼,实验周期90 d,对比两种饲料对点篮子鱼幼鱼的生长性能和消化酶活性影响。结果显示,人工饲料组幼鱼增重率、特定生长率、相对增长率及肌肉的粗蛋白、粗脂肪含量、比内脏重和比肝重均显著高于浒苔组(P0.05),而粗灰分、比肠重、比肠长显著低于浒苔组(P0.05);人工饲料组幼鱼胃中胃蛋白酶活性,前肠和中肠的胰蛋白酶活性,幽门盲囊、肠和肝脏的脂肪酶活性均显著高于浒苔组,而幽门盲囊和肠的淀粉酶活性则显著低于浒苔组(P0.05)。饲喂浒苔的点篮子鱼幼鱼虽然生长性能低于人工饲料组,但其淀粉酶活性、比肠重和比肠长均高于人工饲料组,点篮子鱼对浒苔有良好的摄食和消化能力,浒苔能满足点篮子鱼的生长需求。     

江蓠、浒苔、藻渣和菌渣替代鱼粉对红鳍东方鲀幼鱼生长性能、相关生化指标的影响

本实验旨在研究江蓠(Gracilaria verrucosa)、浒苔(Enteromorpha prolifera)、藻渣和菌渣替代鱼粉对红鳍东方鲀(Takifugu rubripes)幼鱼生长性能、血清和肝脏生化指标和体组成的影响。实验共制成6种等氮、等脂的饲料，以含鱼粉60%为对照组1和45%鱼粉的为对照组2，分别将10%的江蓠、浒苔、藻渣、菌渣与植物蛋白质配合后替代对照组1饲料中30%的鱼粉，投喂初始体重为(17.33±0.55) g的红鳍东方鲀幼鱼56 d。结果显示，1)浒苔组特定生长率(SGR)显著高于其他5组(P<0.05)，藻渣组SGR显著高于对照组2和江蓠组(P<0.05)，与对照组1和菌渣组无显著差异(P>0.05)；对照组1和浒苔组饲料效率(FER)显著高于对照组2和菌渣(P<0.05)，与江蓠和藻渣组无显著差异(P>0.05)；对照组1的蛋白质沉积率(PPV)和蛋白质效率(PER)显著高于对照组2和菌渣组(P<0.05)，与江蓠、浒苔和藻渣组无显著差异(P>0.05)。2)各组血清和肝脏中谷丙转氨酶(GPT)和谷草转氨酶(GOT)活性均无显著差异(P>0.05)。各组血清丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性均无显著差异(P>0.05)。3)菌渣组鱼体粗蛋白质含量显著高于藻渣组(P<0.05)，与对照组1、对照组2、江蓠和浒苔无显著差异(P>0.05)；浒苔和藻渣组鱼体粗脂肪含量显著高于对照组2 (P<0.05)，与对照组1、江蓠和菌渣组无显著差异(P>0.05)。综合来看，将10%江蓠、浒苔、藻渣和菌渣与植物蛋白质配合后替代饲料中30%的鱼粉对红鳍东方鲀幼鱼的生长性能无不良影响，并且浒苔可以显著提高红鳍东方鲀的生长性能。     

浒苔营养成分分析与投喂刺参试验

进行了浒苔(Enteromorpha prolifera)的营养成分测定及投喂刺参(Apostichopus japonicus)的生长试验观察。营养成分检测结果显示,浒苔是一种高蛋白、低脂肪、矿物元素含量丰富的安全藻类食品。另外,分别以浒苔、海泥、浒苔∶海泥(质量比3∶7)、配合饵料∶海泥(质量比3∶7)4种饲料投喂刺参30 d。试验结果:浒苔∶海泥(3∶7)组既有最好的增重率,也有良好的成活率和健康状况;配合饵料∶海泥(3∶7)组次之;而单独投喂浒苔组或海泥组则表现较差。研究结果表明,浒苔具有良好的营养作用,可替代马尾藻、鼠尾藻、海带等作为一种优质的刺参养殖用饵料源。     

不同浒苔型饲料对幼刺参(Apostichopus japonicus)生长、消化及非特异性免疫的影响

以浒苔、石莼、豆粕、扇贝边、葡萄糖、贝壳粉、维生素和矿物质预混料为原料配制刺参(Apostichopus japonicus)饲料,利用酿酒酵母菌菌液和碱性蛋白酶制剂对刺参饲料进行4种不同的处理,得到5组实验用饲料,分别为对照组、发酵组、酶解组、复合组和鲜浒苔组.将上述饲料饲喂初始体重为(1.92-0.02)g的幼刺参42 d,每种饲料设3个重复,每个重复30头幼刺参.结果显示,不同的浒苔型饲料对幼刺参的存活率(SR)、增重率(WGR)、特定生长率(SGR)和饲料系数(FC)有显著影响(P＜0.05),而对其脏壁比(R)无显著性影响(P＞0.05).复合组和鲜浒苔组SR要显著高于酶解组(P＜0.05),而与其他2组均无显著性差异(P＞0.05).鲜浒苔组WGR远高于其他各组(P＜0.05),而复合组和发酵组WGR显著高于酶解组(P＜0.05),与对照组差异不显著(P＞0.05).幼刺参的SGR规律与WGR一致.鲜浒苔组FC显著低于对照组、发酵组和酶解组(P＜0.05),与复合组差异不显著(P＞0.05).随着摄食饲料时间的推移,对照组、发酵组、复合组和鲜浒苔组淀粉酶(AMS)活力先升高再下降后趋于稳定,而酶解组一直呈现下降趋势.酶解组纤维素酶(Cellulase)活力呈现一直下降的趋势,而其他组呈现波动变化,且均高于初始活力值.随着摄食饲料时间的推移,除酶解组外,其余各组胰蛋白酶(TRY)活力前后时间点变化差异不大,且每个采样点幼刺参TRY活力大小顺序始终是对照组＞复合组＞鲜浒苔组＞发酵组＞酶解组.不同浒苔型饲料饲喂的幼刺参体腔液中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和超氧化物歧化酶(SOD)活力均有显著性差异(P＜0.05).鲜浒苔组ACP活力最大,且与复合组无显著性差异(P＞0.05),而显著高于其他3组(P＜0.05).鲜浒苔组和复合组AKP活力显著高于酶解组和对照组(P＜0.05),与发酵组无显著性差异(P＞0.05).复合组SOD活力最大,且显著高于发酵组和酶解组(P＜0.05),而与对照组和鲜浒苔组均无显著性差异(P＞0.05).由此得出,幼刺参在摄食先酶解后发酵的饲料后能够得到良好的生长效果,并可改善自身肠道消化,维持正常免疫.这为解决刺参饲料原料短缺以及浒苔高值化利用提供了依据和方法.     

不同浒苔型饲料对幼刺参(Apostichopus japonicus)生长、消化及非特异性免疫的影响

以浒苔、石莼、豆粕、扇贝边、葡萄糖、贝壳粉、维生素和矿物质预混料为原料配制刺参(Apostichopus japonicus)饲料,利用酿酒酵母菌菌液和碱性蛋白酶制剂对刺参饲料进行4种不同的处理,得到5组实验用饲料,分别为对照组、发酵组、酶解组、复合组和鲜浒苔组。将上述饲料饲喂初始体重为(1.92±0.02)g的幼刺参42 d,每种饲料设3个重复,每个重复30头幼刺参。结果显示,不同的浒苔型饲料对幼刺参的存活率(SR)、增重率(WGR)、特定生长率(SGR)和饲料系数(FC)有显著影响(P0.05),而对其脏壁比(R)无显著性影响(P0.05)。复合组和鲜浒苔组SR要显著高于酶解组(P0.05),而与其他2组均无显著性差异(P0.05)。鲜浒苔组WGR远高于其他各组(P0.05),而复合组和发酵组WGR显著高于酶解组(P0.05),与对照组差异不显著(P0.05)。幼刺参的SGR规律与WGR一致。鲜浒苔组FC显著低于对照组、发酵组和酶解组(P0.05),与复合组差异不显著(P0.05)。随着摄食饲料时间的推移,对照组、发酵组、复合组和鲜浒苔组淀粉酶(AMS)活力先升高再下降后趋于稳定,而酶解组一直呈现下降趋势。酶解组纤维素酶(Cellulase)活力呈现一直下降的趋势,而其他组呈现波动变化,且均高于初始活力值。随着摄食饲料时间的推移,除酶解组外,其余各组胰蛋白酶(TRY)活力前后时间点变化差异不大,且每个采样点幼刺参TRY活力大小顺序始终是对照组复合组鲜浒苔组发酵组酶解组。不同浒苔型饲料饲喂的幼刺参体腔液中酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和超氧化物歧化酶(SOD)活力均有显著性差异(P0.05)。鲜浒苔组ACP活力最大,且与复合组无显著性差异(P0.05),而显著高于其他3组(P0.05)。鲜浒苔组和复合组AKP活力显著高于酶解组和对照组(P0.05),与发酵组无显著性差异(P0.05)。复合组SOD活力最大,且显著高于发酵组和酶解组(P0.05),而与对照组和鲜浒苔组均无显著性差异(P0.05)。由此得出,幼刺参在摄食先酶解后发酵的饲料后能够得到良好的生长效果,并可改善自身肠道消化,维持正常免疫。这为解决刺参饲料原料短缺以及浒苔高值化利用提供了依据和方法。     

浒苔中MnSOD和CAT基因克隆和表达分析

实验以大型绿藻浒苔为材料,克隆了其抗氧化系统关键酶锰超氧化物歧化酶(manganese superoxide dismutase,Mn SOD)和过氧化氢酶(catalase,CAT)基因的部分片段,利用荧光定量PCR技术研究了Mn SOD和CAT对温度和水杨酸作用的响应规律。结果获得浒苔318 bp的Mn SOD基因,该Mn SOD推测的氨基酸序列与裂片石莼Mn SOD相似性最高为89%;获得了229 bp的CAT基因,该浒苔CAT编码氨基酸序列与裂片石莼和雨生红球藻CAT序列相似性分别为99%和93%。在利用M n SOD和CAT氨基酸序列构建的系统树中,浒苔均先与裂片石莼聚类,再与其他绿藻聚在一起。不同温度对浒苔Mn SOD和CAT基因表达影响表明,35℃高温培养对浒苔Mn SOD和CAT基因表达影响最显著,其表达量分别为25℃培养的2.18倍和2.05倍;5℃低温培养次之;而15℃与25℃培养对M n SOD和CAT基因表达影响差异不显著(P0.05)。在高温35℃下,添加0.1 mmol/L水杨酸后Mn SOD和CAT基因表达量分别为各自对照的2.08倍和5.30倍,而0.01 mmol/L水杨酸添加后基因表达与对照差异不显著(P0.05)。研究表明,Mn SOD和CAT基因表达的增强不仅是浒苔对高温胁迫的响应,而且也是水杨酸缓解高温对浒苔不利影响的方式之一。     

Growth and Body Composition Effects of Tuna Byproduct Meal Substituted for Fish Meal in the Diet of Juvenile Abalone,Haliotis discus

The effects on growth and body composition that result from tuna byproduct meal (TBM) substituted for fish meal in the diet of juvenile abalone, Haliotis discus, were determined. One thousand two hundred sixty juvenile abalone were randomly distributed into 18 70‐L plastic rectangular containers. Six experimental diets were prepared in triplicate. The TBM0 diet included 28% fish meal and 13% soybean meal as the protein source. Twenty‐five, 50, 75, and 100% of the fish meal were substituted with TBM. Finally, salted sea tangle was prepared. The essential amino acids, such as isoleucine, lysine, and valine, tended to decrease with the dietary substitution of TBM for fish meal in the experimental diets. The weight gain and specific growth rate (SGR) of abalone that were fed the TBM25 diet were higher than those of abalone that were fed the other diets. The crude protein content of the soft body of the abalone linearly decreased with the dietary substitution of TBM for fish meal. In conclusion, as much as 75% of the fish meal in the diet of abalone can be replaced with TBM without retardation in weight gain and SGR of the abalone when 28% fish meal was included.     

A novel konjac glucomannan–xanthan gum binder for aquaculture feeds: the effect of binder configuration on formulated feed stability,feed palatability and growth performance of the Japanese abalone,Haliotis discus hannai

As part of a programme to develop sustainable diets for macroalgivores, a 3‐month experiment was conducted to determine the effects of konjac glucomannan–xanthan gum (KX) binder configuration on formulated feed stability, feed palatability and growth performance of juvenile, hatchery‐reared, Haliotis discus hannai. This study was conducted in a recirculation facility in which four KX binder configurations were evaluated in a series of isonitrogenous experimental feeds and freshly harvested Laminaria digitata was included as a natural feed type. Dry matter leaching of the experimental feed treatments was assessed with no significant difference in the dry matter leaching between treatments observed. No differences (P > 0.05) were found in percentage survival, daily food consumption (DFC) and linear growth rate (LGR) between treatments. Food conversion efficiency (FCE), specific growth rate (SGR) and body weight/shell length (BW/SL) ratio were significantly higher when offered L. digitata. Trends showed that the best performing KX feed in terms of FCE, LGR, SGR and BW/SL ratio was produced with the 2% KX; 1 : 1 binder.     

Effects of dietary substitution of fishmeal with the combined dry microalgae,Nannochloropsis oceanica (NO) biomass residue and casein on growth and body composition of juvenile abalone (Haliotis discus)

The effects of dietary substitution of fishmeal with the combined dry Nannochloropsis oceanica (NO) biomass residue and casein on growth performance and carcass composition of juvenile abalone was determined. One thousand two hundred and sixty juvenile abalone were randomly distributed into the 18 L plastic rectangular containers. Five experimental diets in triplicate were prepared. The 28% fishmeal was included into the control (Con) diet. The 25%, 50%, 75% and 100% fishmeal were substituted with the combination of graded levels of dry NO biomass residue and casein, referred to as the NO25, NO50, NO75 and NO100 diets respectively. Finally, the salted sea tangle (ST), Laminaria japonica was prepared to compare the effect of the experimental diets on performance of abalone. The essential amino acids, such as isoleucine, leucine, phenylalanine, threonine and valine tended to increase with dietary substitution of fishmeal with NO biomass residue in the experimental diets. Arginine tended to decrease with dietary substitution of fishmeal with NO biomass residue. Survival of abalone fed the experimental diets was higher than that of abalone fed the ST diet for 16 weeks. Weight gain and specific growth rate (SGR) of abalone fed the NO100 diet were higher than those of abalone fed the all other diets. Weight gain and SGR of abalone linearly increased with dietary substation of fishmeal with NO. Shell length of abalone tended to increase with dietary substitution of fishmeal with the combined dry NO biomass residue and casein. The chemical composition of the soft body of abalone was different among treatments except for moisture content. In conclusion, fishmeal in the diets for abalone could be completely replaced with the combined dry NO biomass residue and casein when the 28% fishmeal was included.     

Use of thraustochytrid <Emphasis Type="Italic">Schizochytrium</Emphasis> sp. as source of lipid and fatty acid in a formulated diet for abalone <Emphasis Type="Italic">Haliotis asinina</Emphasis> (Linnaeus) juveniles

The effects of using thraustochytrid Schizochytrium sp. as source of lipid and fatty acids in a formulated diet on growth, survival, body composition, and salinity tolerance of juvenile donkey’s ear abalone, Haliotis asinina, were investigated. Treatments consisted of diets either containing a 1:1 ratio of cod liver oil (CLO) and soybean oil (SBO) (Diet 1) or thraustochytrid (Diet 2) as source of lipid and fatty acids at 2 % level. Natural diet Gracilariopsis heteroclada (Diet 3) served as the control. No significant difference in growth was observed in abalone fed Diet 3 (SGR: 5.3 % BW day^?1; DISL: 265 μm day^?1) and Diet 2 (SGR: 5.2 % BW day^?1; DISL: 255 μm day^?1). Survival ranged from 78 to 85 % for all treatments and was not significantly different from each other. A 96-h salinity stress test showed highest survival of 84 % in abalone fed Diet 2 compared with those fed diets 1 and 3 (42 %). The high growth rate of abalone fed Diet 2 and high tolerance to low salinity could be attributed to its high DHA content (8.9 %), which resulted to its high DHA/EPA ratio of 10.5 %. These fatty acids play a significant role in abalone nutrition. The fatty acid profile of abalone meat is a reflective of the fatty acid profile of the oil sources in the diet. The present study suggests that the use of Schizochytrium oil in lieu of CLO and SBO can support good growth of abalone which is comparable with abalone fed the natural seaweeds diet.     

Effects of Algae and Shell Pigment Extract‐supplemented Diets on Shell Pigmentation and Growth Performance of Pacific Abalone,Haliotis discus hannai

To improve shell pigmentation and growth performance of Pacific abalone, five extruded diets were prepared by supplementing a formulated control diet with 3% each of three species of algae (Pacific dulse, Porphyra yezoensis, Spirulina) and a pigment extract from the abalone shells (0.02%). Each of the five diets and a commercial feed were randomly assigned to three containers each stocked with 1000 juvenile Pacific abalone (2 g per individual) in a flow‐through seawater system for a 5‐mo feeding trial. Test results showed: (1) all the supplements significantly (P < 0.05) increased percentages of dark‐brown shelled abalone in the test treatments, relative to the control treatment; (2) the abalone fed the experimental diets achieved significantly (P < 0.05) greater final weight, shell‐length growth rates, and higher meat protein contents than those fed the commercial feed (P < 0.05); and (3) the abalone fed the Spirulina‐supplemented diet achieved the best overall growth, pigmentation performances, and feed conversion ratio; and the Pacific dulse supplement generated the highest protein content in abalone meat product (P < 0.05) among the tested diets. These results demonstrate the potential of locally made feed, which can generate desirable characteristics in abalone under aquaculture conditions.     

Substitution effect of Undaria pinnatifida with citrus (Citrus unshiu,Marcovitch) peel by‐product in feed on the growth,body composition and air exposure stressor of juvenile abalone (Haliotis discus,Reeve 1846)

Substitution effect of Undaria pinnatifida with citrus peel by‐product (CPB) on growth, body composition and air exposure stressor of abalone was determined. A total of 1,080 abalone were distributed into 18 net cages. Five formulated diets were prepared in triplicate. The CPB0 diet contained 200 g/kg U. pinnatifida. The 250, 500, 750 and 1,000 g/kg U. pinnatifida were substituted with the equal amount of CPB, referred to as the CPB250, CPB500, CPB750 and CPB1000 diets, respectively. Finally, dry U. pinnatifida was prepared. Abalone were fed for 16 weeks and then subjected to air exposure stressor for 24 hr. The cumulative mortality of abalone was monitored for the following 4 days after 24‐hr air exposure. Survival, weight gain and specific growth rate (SGR) of abalone fed all formulated diets were greater than those of abalone fed the U. pinnatifida. The greatest weight gain and SGR were achieved in abalone fed the CPB500 diet. The chemical composition of the soft body of abalone was not affected by the experimental diets. Higher cumulative mortality was observed in abalone fed the CPB0 and dry U. pinnatifida at 16 hr after 24‐hr air exposure compared to abalone fed all other diets. In conclusion, U. pinnatifida could be completely substituted with CPB in abalone feed.     

Effect of Dietary Carbohydrate‐to‐Lipid Ratio on Growth and Carcass Composition of Juvenile Abalone,Haliotis discus,Reeve 1846

The optimal dietary carbohydrate (C) : lipid (L) ratio on growth and carcass composition of juvenile abalone, Haliotis discus, was determined. A total of 1260 juveniles were randomly distributed into 18 containers. Six experimental diets containing different ratios of C to L (49:1, 48:2, 47:3, 45:5, 43:7, and 41:9) were prepared and referred to as the C49:L1, C48:L2, C47:L3, C45:L5, C43:L7, and C41:L9 diets, respectively. Water stability of the experimental diets was measured 12, 24, and 48 h after seawater immersion. Crude protein, L and ash content of the experimental diets decreased with time. Survival of abalone fed the C48:L2 diet was higher than that of abalone fed the C49:L1 and C41:L9 diets. Weight gain and specific growth rate (SGR) of abalone fed the C49:L1, C48:L2, and C47:L3 diets were higher than that of abalone fed the C45:L5, C43:L7, and C41:L9 diets. Crude L content of the soft body of abalone was directly reflected from dietary crude L content. In conclusion, the optimal dietary C : L ratio was estimated to be 48:2 and 47:3 based on survival, weight gain, and SGR of juvenile abalone, respectively. Greater than 3% L content in the diet deteriorated performance of this species of abalone.     

Effect of dietary substitution of sea tangle (ST), Laminaria japonica with rice bran (RB) on growth and body composition of juvenile abalone (Haliotis discus)

Dietary substitution effect of sea tangle (ST) with rice bran (RB) on growth and carcass composition of juvenile abalone (Haliotis discus) was determined. Juvenile abalone was acclimated to the experimental conditions for 4 weeks. Seventy juvenile abalone averaging 0.43 g were randomly distributed into each of the 18, 70 L plastic rectangular containers. The experimental diets were fed to abalone once a day at a satiation level with a little leftover. The feeding trial lasted for 16 weeks. Survival of abalone was not affected by dietary substitution of ST with RB. However, weight gain of abalone fed the RB40 diet was higher than that of abalone fed the all other diets except for the RB0 diet. No significant difference in weight gain was found in abalone fed between the RB0 and RB100 diets. SGR of abalone fed the RB40 diet was higher than that of abalone fed the all other diets. Also SGR of abalone fed the RB0 diet was higher than that of abalone fed the RB100 diet, but not different from that of abalone fed the RB20, RB60 and RB80 diets. Moisture, crude protein and ash content of the soft body of abalone were affected by dietary substitution of ST with RB. In conclusion, the 100% ST could be substituted with RB without a retardation of weight gain of abalone when the 20% ST was included into the experimental diet. However, the best growth performance was obtained in abalone fed the RB40 diet substituting 40% ST with RB.     

Evaluation of Enteromorpha prolifera as a feed component in large yellow croaker (Pseudosciaena crocea,Richardson, 1846) diets

A 9‐week feeding trial was conducted to investigate the effects of dietary Enteromorpha prolifera on the growth performance and body composition of juvenile large yellow croaker (Pseudosciaena crocea) (Richardson, 1846) (11.41 ± 1.59 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Four isonitrogenous and isoenergetic diets were formulated to contain graded levels (0%, 5%, 10% and 15%) of E. prolifera. Survival ranged from 98.7% to 99.7%, and was independent of dietary treatment (P>0.05). There were no significant differences in the feeding rate among dietary treatments (P>0.05). The specific growth rate (SGR) increased with increasing levels of E. prolifera. When the supplementation of E. prolifera was >5%, SGR was significantly higher compared with the control group (0%). The feed efficiency ratio (FER) in fish fed the diet with 5%E. prolifera (diet 2) was higher than that of the other groups, while in fish fed the diet with 10%E. prolifera (diet 3), it was the lowest (P<0.05). The protein retention (PR) decreased as the level of E. prolifera increased in diets (5%, 10% and 15%). The protein body content displayed a trend similar to that of PR. No significant difference was observed in body moisture and ash among the dietary treatments. An increase in minerals of potassium, magnesium and sodium in body was observed with an increase in dietary seaweed concentrations. On basis of the SGR and FER, supplementation levels of E. prolifera can reach at least 15% without affecting the growth and still maintain a high survival rate for juvenile large yellow croaker.     

A study on dietary l‐lysine requirement of juvenile yellow catfish Pelteobagrus fulvidraco

An 8‐week feeding trial was conducted to determine lysine requirement of juvenile yellow catfish (Pelteobagrus fulvidraco) by feeding formulated diets containing crystalline l ‐lysine. Six isonitrogenous and isoenergetic diets (405 g kg^?1 protein, 18 kJ g^?1 gloss energy) containing fish meal together with soybean protein concentrate as protein sources and fish oil together with soybean oil as lipid sources were formulated. Crystalline l ‐lysine was added into the six diets to acquire lysine concentrations of 17.3, 21.8, 26.0, 31.3, 35.5 and 41.9 g kg^?1 dry diets, respectively. Mixture of crystalline amino acid was supplemented to simulate the amino acid profile in muscle of yellow catfish. The results indicated that final body weight (FBW), weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency (PE) increased with the increase in dietary lysine level from 17.3 to 31.3 g kg^?1 of diet and then decreased as the dietary lysine levels further increased. No significant difference in survival rate was found among all the dietary treatments. One‐slope, quadratic broken‐line analysis on the basis of SGR showed that the dietary l ‐lysine requirement of juvenile yellow catfish was 33.1 g kg^?1 of dry diet (83.2 g kg^?1 of dietary protein).