温度和光照对塔胞藻生长的影响

采用梯度法比较了温度、光照度、光照周期对一次性培养的塔胞藻生长的影响。结果表明:塔胞藻对温度的适应范围较广,10~30℃时塔胞藻均可生长,24~28℃为塔胞藻生长的最适温度;光照度4000~10 000 lx时,塔胞藻生物量随光照度的增加而增大,并在10 000 lx时达到最大;塔胞藻在光照周期为16L∶8D时生长最快。     

几种金属离子对沼泽红假单胞菌2-8生长和亚硝酸盐消除的影响

在培养基中添加一定浓度金属离子,研究了不同浓度铜离子（Cu2＋）、镁离子（Mg2＋）、锌离子（Zn2＋）、铁离子（Fe3＋）和锰离子（Mn2＋）对沼泽红假单胞菌（Rhodopseudom onas palustris）2-8株生长和亚硝酸盐消除能力的影响。结果发现,1×10-7mol.L-1Cu2＋刺激菌株生长和亚硝酸盐消除,1×10-4mol.L-1Cu2＋抑制生长和亚硝酸盐消除,1×10-6mol.L-1和1×10-5mol.L-1的Cu2＋抑制生长,但刺激亚硝酸盐消除;1×10-4mol.L-1Mg2＋刺激菌株生长和亚硝酸盐消除;不同浓度Zn2＋对菌体生长影响不显著,但浓度为1×10-6mol.L-1和1×10-7mol.L-1时刺激亚硝酸盐消除,浓度大于1×10-6mol.L-1时抑制亚硝酸盐消除;Fe3＋促进生长,浓度越高生长越好,对菌株亚硝酸盐消除的影响则刚好相反;不同浓度Mn2＋均抑制菌株生长,1×10-6～1×10-3mol.L-1Mn2＋抑制亚硝酸盐消除。受测定的5个金属离子中除1×10-4mol.L-1Cu2＋对菌株亚硝酸盐消除能力的抑制较强外,其他离子的抑制会随时间推移逐渐消失。     

温度对凸壳肌蛤能量收支的影响

凸壳肌蛤(Arcuatula senhousei)是虾蟹等养殖品种的优质饵料生物,也是极具养殖潜力的贝类品种。为了深入了解其生理代谢,利用室内静水法对不同温度(7℃、15℃、23℃、31℃)凸壳肌蛤的摄食率、排粪率、耗氧率、排氨率等生理指标进行了研究,并建立了能量收支方程。结果显示,23℃时的滤水率、摄食率、耗氧率、同化效率均显著高于其他温度梯度(P0.05),分别达到了1.09 L/(g·h)、24.46 mg/(g·h)、3.50 mg/(g·h)和62.93%;7℃时的滤水率、摄食率、耗氧率、排粪率、排氨率均低于其他温度梯度,分别为0.24 L/(g·h)、6.04 mg/(g·h)、1.02 mg/(g·h)、4.20 mg/(g·h)、2.33μmol/(g·h)。且滤水率、摄食率、耗氧率、同化效率随着温度升高都呈先升高后下降的趋势,在23℃时均达到最高值。不同温度下的能量收支方程为:100C=58.12F+46.74R+2.54U–7.40P(7℃);100C=44.28F+29.14R+1.85U+24.73P(15℃);100C=17.18F+41.81R+6.64U+34.37P(23℃);100C=53.35F+28.26R+14.66U+3.73P(31℃)。能量收支研究表明,生长能(P)、呼吸能(R)、排泄能(U)和粪便能(F)占摄食能(C)的比例分别为–7.4%~34.37%、28.26%~46.74%、1.85%~14.66%、17.18%~58.12%,23℃时生长能占摄食能的比例显著高于其他温度梯度(P0.05),达到了34.37%;7℃时最低,为–7.40%。研究结果为深入了解凸壳肌蛤的生理能量学提供了数据支撑。     

几种重金属离子毒性对黑鲷卵子和稚鱼的影响

在黑鲷人工繁殖中,发现海水中重金属离子对黑鲷的稚鱼及卵子的发育有影响,因而作了Hg~(2+)、Cr~(6+)、Fe~(2+)、Cu~(2+)几种重金属离子对黑鲷稚鱼影响的探讨。找出了安全浓度,并提出亚铁的毒性不可忽略,其特点为死亡界限明显,过渡段短;同时发现几种毒物随着水温的升高,其毒性由强到弱的排列顺序为:Hg~(2+)>Fe~(2+)>Cu~(2+)>Cr~(6+),用直线内涵法求出了TL_(m21)、TL_(m18)、TL_(m96)浓度。     

几种重金属离子毒性对黑鲷孵子和稚鱼的影响

在黑鲷人工繁殖中，发现海水中重金属离子对黑鲷的稚鱼及孵子的发育有影响，因而作了Ｈｇ＾２＋，Ｃｒ＾６＋，Ｆｅ＾２＋，Ｃｕ＾２＋几种重金属离子对黑鲷雅鱼影响的探讨。找出安全浓度，并提出亚铁的毒性不可忽略，其特点为死亡界限明显，过渡段；时发现几种毒物随着水温的升高。其毒性由强到弱的排列顺序为：Ｈｇ＾２＋＞Ｆｅ＾２＋＞Ｃｕ＾２＋＞Ｃｒ＾６＋，用直线内插法求出了ＴＬｍ２４、ＴＬｍ１８、ＴＬｍ９６浓度。     

4种金属离子对宝石鲈蛋白酶活性的影响

以酶学方法研究了K+、Na+、Mg2+、Ca2+ 在浓度为50、100、150、200、250、300 mmol/L时,对宝石鲈消化器官(胃、幽门盲囊、肝脏、前肠、中肠、后肠)蛋白酶活性的影响.试验结果表明,K+、Na+对宝石鲈消化器官蛋白酶活性具有一定的促进作用,100 mmol/L时促进作用最明显;Mg2+、Ca2+对蛋白酶活性具有抑制作用,300 mmol/L时抑制作用最大;蛋白酶在宝石鲈各消化器官的分布为前肠＞幽门盲囊＞中肠＞胃＞肝脏＞后肠.宝石鲈配合饲料中添加100 mmol/L的K+、Na+可提高其消化器官的蛋白酶活性.     

几种金属离子对鲢肝胰脏淀粉酶的影响

以鲢的肝胰脏为材料,取组织匀浆上清液作为酶液进行研究.结果表明:鲢肝胰脏淀粉酶的最适pH为6.8,最适温度为35℃,最适底物浓度为0.03%.进一步研究1、2价金属离子和重金属离子对鲢肝胰脏淀粉酶活力的影响,结果表明:1价金属离子K+、Na+对酶活力没有影响,2价金属离子Ba2+、Ca2+对酶活力具有抑制作用,重金属离子Cd2+、Hg2+对酶活力具有显著的抑制作用.     

草鱼酸性磷酸酯酶的性质及金属离子对其活性的影响

以草鱼肝脏为材料提取一种酸性磷酸酯酶(ACPase,EC.3.1.3.2),进一步用(NH4)2SO4沉淀分离,Sephadex G-200柱纯化,经聚丙烯酰胺凝胶电泳纯度鉴定呈现单一酶蛋白带,该酶紫外吸收峰为240nm和280nm,等电点为4.8,相对分子质量为100046.1。该酶水解对硝基苯磷酸二钠(pNPP)的最适pH值为4.4,最适温度为45℃,并有热激活现象,热激活温度为60℃。耐热实验表明,该酶在最适温度下耐热时间为33min,最适温度下20min时表现出最大活性。在60℃下耐热时间为25min,15min时表现最大活性。酶促反应初速度为0.0475μmol/min,最大反应速度为0.153μmol/min。米氏常数Km值为3.56×10-3mol/L。金属离子对酶活性影响的研究结果表明,K+对酶有激活作用,Li+、Na+对酶的活性没有明显影响;碱土金属离子Mg2+、Ca2+和Ba2+对酶有激活作用,其激活程度由大到小依次为:Ba2+、Mg2+、Ca2+;Mn2+对酶有激活作用,Zn2+、Cu2+、Co2+则有抑制作用;重金属离子Hg2+、Pb2+、Ag+和Cd2+对酶有抑制作用,其中Hg2+的抑制效应最强。Mg2+和Cu2+的作用机制研究结果表明,Mg2+对酶具有混合型激活作用,Cu2+对酶具有竞争性抑制作用。     

混合金属离子Pb、Zn和Cu的相互作用对Cd在鲫体内积累的影响

采用室内生态学方法研究混合重金属离子Pb、Zn和Cu的相互作用对Cd在鲫组织中积累的影响.结果表明,混合重金属离子相互作用对Cd在鲫组织中积累的影响与离子的种类、数量及组织类型有关.Cd的积累受单一重金属影响不显著,与Pb、Zn、Cu的混合作用关系密切.随重金属离子种类的增加,相互作用对积累的影响显著;Pb、Zn、Cu的混合降低了Cd在鳃中的积累量,增加了Cd在肝脏中的积累量,对Cd在肌肉中的积累无影响.Cd在鲫组织中的积累顺序为:肝胰脏>鳃>肌肉.     

四种金属离子对宝石鲈（Scortum barcoo）淀粉酶活性的影响

以酶学分析方法研究了四种金属离子K^＋、Na^＋、Mg^2＋、Ca^2＋对宝石鲈消化器官（胃、幽门盲囊、肝脏、前肠、中肠、后肠）淀粉酶活性的影响。金属离子浓度设置为50～300mmol／L六个梯度。结果表明,K^＋、Na^＋、Mg^2＋对大部分消化器官淀粉酶活性表现为低浓度促进,高浓度抑制的作用（P〈0．05）,50mmol／L和100mmol／L时促进作用最大,三者中K^＋促进作用最明显,其次为Na^＋和Mg^2＋;Ca^2＋可明显抑制各消化器官淀粉酶活性（P〈0．05）;四种离子的最大抑制作用出现在250mmol／L和300mmol／L两个高浓度下。淀粉酶在宝石鲈各消化器官的分布为前肠〉幽门盲囊〉胃〉中肠〉肝脏〉后肠。由此得出结论：50—100mmol／L的K^＋、Na^＋、Mg^2＋对宝石鲈淀粉酶活性促进作用最明显,在配合饲料中可适量添加。     

Effects of different dietary arachidonic acid : docosahexaenoic acid ratios on phospholipid fatty acid compositions and prostaglandin production in juvenile turbot (Scophthalmus maximus)

Five purified diets containing AA (20:4n-6) at 0.02–0.78% dry weight and DHA (22:6n-3) at 0.93–0.17% dry weight were fed to duplicate groups of juvenile turbot (Scophthalmus maximus) of initial weight 0.87 g for a period of 11 weeks. The dietary DHA:AA ratio ranged from 62 to 0.2. Incorporation of AA into liver phospholipids increased with increasing dietary AA input. Phospholipids from fish fed diets containing 0.02, 0.06 and 0.11% of dry weight as AA generally contained less AA compared to fish fed fish oil while those fed diets containing 0.35 and 0.78% of dry weight as AA had higher AA levels in their phospholipids. The highest levels of AA were found in PI but the greatest percentage increase in AA incorporation was in PE and PC. Brain phospholipid fatty acid compositions were less altered by dietary treatment than those of liver but DHA content of PC and PE in brain was substantially lower in fish fed 0.93% pure DHA compared to those fed fish oil. This suggests that dietary DHA must exceed 1% of dry weight to satisfy the requirements of the developing neural system in juvenile turbot. In both tissues, (20:5n-3) concentration was inversely related to both dietary and tissue PI AA concentration. Similar dietary induced changes in AA, EPA and DHA concentrations occurred in the phospholipids of heart, gill and kidney. PGE₂ and 6-ketoPGF₁ were measured in homogenates of heart, brain, gill and kidney. In general, fish fed the lowest dietary AA levels had reduced levels of prostaglandins in their tissue homogenates while those fed the highest level of AA had increased prostaglandin levels, compared to fish fed fish oil. In brains, the PGE₂ concentration was only significantly increased in fish fed the highest dietary AA.Abbreviations AA arachidonic acid - DHA docosahexaenoic acid - EFA essential fatty acid - EPA eicosapentaenoic acid - HPTLC high performance thin-layer chromatography - HUFA highly unsaturated fatty acid - PC phosphatidylcholine - PE phosphatidylethanolamine - PGE prostaglandin E - PGE prostaglandin E - PI phosphatidylinositol - PS phosphatidylserine - PUFA polyunsaturated fatty acid - TLC thin-layer chromatography     

Amino acid profiles and amino acid utilization in larval African catfish (Clarias gariepinus): effects of ontogeny and temperature

The present study investigated the qualitative amino acid (AA) requirements of larval African catfish Clarias gariepinus. Yolk-sac larval AA profiles were measured at different temperatures and also in animals reared at 28 °C fed Artemia nauplii or an experimental dry diet. The AA profile of C. gariepinus larvae changed during ontogeny, especially before the start of exogenous feeding. The AA profiles of the food items (yolk, Artemia and the dry diet) differed considerably from that of the larvae. No selective absorption of yolk AA was detected. Higher temperatures led to increased absorption and depletion rates of AA, and also to a higher retention efficiency of yolk nutrients. However, changes in temperature did not induce preferential absorption or depletion of individual AA, and caused only small variations in the AA profile. Depletion rates of individual AAs varied, possibly due to differences between larval and yolk AA profiles, and also to changes in the larval AA profile during ontogeny. There was little regulation of catabolism of individual AA in yolk-sac and starved larvae, and no sparing of essential AA.     

Effects of salinity and temperature conditions on the reproductive success of turbot (Scophthalmus maximus) in the Baltic Sea

In the Baltic Sea, a large brackish water area, turbot (Scophthalmus maximus) occurs at the border of its distribution with respect to salinity. Using turbot caught in ICES subdivision (SD) 28 (mid-Baltic), salinity requirements for successful egg development were evaluated by assessment of spermatozoa mobility, fertilisation and egg survival at different salinities. Further, to evaluate potential effects of temperatures, egg survival at different temperatures was assessed. Spermatozoa activity and fertilisation rate decreased with decreasing salinity with a significant drop at <7 psu. The viable hatch was significantly lower at <7 psu compared to at 7–15 psu. Hence, due to decreasing salinity this implies lower egg survival in SD 29 and 30 compared to in SD 24–28, and that salinity conditions in SD 31 are insufficient for egg development. Further, following a long period without major inflows of saline water into the Baltic Sea, salinity has decreased. From 1995 onwards salinities <7 psu prevail in SD 27–28 suggesting decreased reproductive success and potentially weaker year-classes in this area. Egg survival was high at 12–18 °C and considerably lower at 9 and 21 °C. Comparing the results with environmental data suggested that spawning time of turbot is adapted to optimum temperatures for egg development, but that occasions with temperatures involving increased egg mortality may occur, e.g. during upwelling situations.     

Effects of body weight, water temperature and ration size on ammonia excretion by the areolated grouper (Epinephelus areolatus) and mangrove snapper (Lutjanus argentimaculatus)

The effects of body weight, water temperature and ration size on ammonia excretion rates of the areolated grouper Epinephelus areolatus and the mangrove snapper Lutjanus argentimaculatus were investigated. Under given experimental conditions, L. argentimaculatus had a higher weight-specific ammonia excretion rate than E. areolatus. Weight-specific ammonia excretion rates of fasted individuals of both species showed an inverse relationship with body weight (W, g wet wt.), but a positive relationship with water temperature (t, °C). The relationships for total ammonia nitrogen (TAN) were: E. areolatus: TAN (mg N kg⁻¹ d⁻¹)=21.4·exp^0.11t·W^−0.43 (r²=0.919, n=60); L. argentimaculatus: TAN (mg N kg⁻¹ d⁻¹)=121.5·exp^0.12t·W^−0.55 (r²=0.931, n=60). Following feeding, the weight-specific ammonia excretion rate of E. areolatus increased, peaked at 2 to 12 h (depending on temperature), and returned to pre-feeding levels within 24 h. A similar pattern was observed for L. argentimaculatus, with a peak of TAN excretion being found 6 to 12 h after feeding. Stepwise multiple regression analysis indicated that weight-specific TAN excretion rates of both species increased with increasing temperature and ration (R, percent body wt. d⁻¹): E. areolatus: TAN (mg N kg⁻¹ d⁻¹)=22.8·t−28.8·R−378.2 (r²=0.832, n=24); L. argentimaculatus: TAN (mg N kg⁻¹ d⁻¹)=22.9·t−25.4·R−216.4 (r²=0.611, n=24). The effect of body weight on weight-specific postprandial TAN excretion was not significant in either species (p>0.05). This study provides empirical data for estimating ammonia excretion of these two species under varying conditions. This has application for culture management.     

饲料中花生四烯酸含量对刺参生长性能、抗氧化能力及脂肪酸代谢的影响

为探究饲料中添加花生四烯酸(arachidonic acid,ARA)对刺参(Apostichopus japonicus)生长性能、抗氧化能力及脂肪酸代谢的影响,选用初始体重为(10.78±0.06)g的刺参为研究对象,以鱼粉和发酵豆粕为主要蛋白质源,小麦粉为主要糖源制作基础饲料,通过在基础饲料中添加不同比例的ARA-纯化油,制成ARA含量分别为0.02%(对照组)、0.17%、0.36%、0.51%、0.59%和0.98%(占饲料干重)的6组等氮等脂的实验饲料,在室内循环水养殖系统进行为期56 d的养殖实验。结果表明,随着饲料中ARA含量的升高,刺参增重率(weight gain rate,WGR)呈先上升后降低的趋势,0.36%和0.51%ARA饲料组刺参WGR显著高于其他处理组(P0.05),刺参的特定生长率(specific growth rate,SGR)和饲料效率(feed efficiency,FE)与WGR具有相同的变化趋势;刺参体壁粗脂肪含量随饲料ARA含量升高呈先降低后升高的趋势,在0.51%ARA饲料组含量最低,且显著低于对照组与0.98%ARA饲料组(P0.05);同时,随饲料中ARA含量的提高,刺参体壁中ARA和n-6多不饱和脂肪酸(n-6 polyunsaturated fatty acids,n-6 PUFA)含量呈显著上升趋势,而二十碳五烯酸(eicosapentaenioc acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和n-3多不饱和脂肪酸(n-3 polyunsaturated fatty acids,n-3 PUFA)含量显著降低(P0.05);抗氧化能力方面,0.36%和0.51%ARA饲料组刺参肠道中超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)和总抗氧化能力酶(total antioxidant capacity enzyme,T-AOC)活性均显著高于对照组与0.98%ARA饲料组(P0.05),而肠道丙二醛(malondialdehyde,MDA)含量呈相反的变化趋势(P0.05);刺参肠道中脂肪酸合成酶(fatty acid synthase,FAS)和乙酰辅酶A羧化酶(acetyl-Co A carboxylase,ACC)活性随饲料ARA含量的升高呈显著降低趋势(P0.05);刺参肠道中肉毒碱棕榈酰转移酶-1(carnitine palmitoyltransferase-1,CPT-1)活性随饲料ARA含量升高呈先升高后降低的趋势(P0.05)。研究表明,在本实验条件下,饲料中添加适量ARA(0.36%~0.51%)能够对刺参生长、抗氧化能力起到一定的促进作用,同时结果显示,饲料ARA含量会对刺参肠道内脂肪酸代谢产生一定的影响。     

饲料组成对银鲳幼鱼生长率及肌肉氨基酸、脂肪酸组成的影响

研究分析了饲料组成对银鲳(Pampus argenteus)幼鱼特定生长率(SGR)及肌肉氨基酸与脂肪酸组成的影响。实验共设4组不同的饲料组成,依次为饲料A(鱼肉糜)、饲料B(鱼肉糜+配合饲料)、饲料C(鱼肉糜+配合饲料+蛏子肉糜)和饲料D(鱼肉糜+配合饲料+蛏子肉糜+桡足类)。实验用银鲳幼鱼的平均体重为4.80±0.11 g,每组饲料设3重复,实验周期为9周。研究结果显示,不同饲料组成可显著影响银鲳的特定生长率,饲料A组的特定生长率最低,并显著低于其它各饲料组;饲料D组的特定生长率最高,且显著高于饲料B、C组的特定生长率(P<0.05);但饲料B、C组间银鲳特定生长率无显著性差异(P>0.05)。银鲳肌肉氨基酸与脂肪酸的分析结果显示,4组饲料组成对银鲳肌肉氨基酸的组成及含量并无显著性影响(P>0.05),但可显著影响肌肉脂肪酸的组成及含量(P<0.05)。饲料D组的多不饱和脂肪酸(PUFA)、高度不饱和脂肪酸(HUFA)及n-3HUFA含量均分别显著高于饲料A、B和C组(P<0.05),饲料B和C组的PUFA、HUFA及n-3HUFA均分别显著高于饲料A组(P<0.05),但饲料B、C组间并无显著性差异(P>0.05)。综合分析得出,丰富的饲料组成以及饲料中较高的HUFA含量均有利于银鲳幼鱼的生长。     

Effects of dietary eicosapentaenoic acid on growth, survival, pigmentation and fatty acid composition in Senegal sole (Solea senegalensis) larvae during the Artemia feeding period

We examined the effect of dietary eicosapentaenoic acid (EPA, 20:5n‐3) on growth, survival, pigmentation and fatty acid composition of Senegal sole larvae. From 3 to 40 days post‐hatch (dph), larvae were fed live food that had been enriched using one of four experimental emulsions containing graduated concentrations of EPA and constant docosahexaenoic acid (DHA, 22:6n‐3) and arachidonic acid (ARA, 20:4n‐6). Final proportions of EPA in the enriched Artemia nauplii were described as ‘nil’ (EPA‐N, 0.5% total fatty acids, TFA), ‘low’ (EPA‐L, 10.7% TFA), ‘medium’ (EPA‐M, 20.3% TFA) or ‘high’ (EPA‐H, 29.5% TFA). Significant differences among dietary treatments in larval length were observed at 25, 30 and 40 dph, and in dry weight at 30 and 40 dph, although no significant correlation could be found between dietary EPA content and growth. Eye migration at 17 and 25 dph was affected by dietary levels of EPA. Significantly lower survival was observed in fish fed EPA‐H diet. Lower percentage of fish fed EPA‐N (82.7%) and EPA‐L (82.9%) diets were normally pigmented compared with the fish fed EPA‐M (98.1%) and EPA‐H (99.4%) enriched nauplii. Tissue fatty acid concentrations reflected the corresponding dietary composition. ARA and DHA levels in all the tissues examined were inversely related to dietary EPA. This work concluded that Senegal sole larvae have a very low EPA requirement during the live feeding period.     

Effect of ethanol, clofibric acid and temperature on the uptake and elimination of 2-methylisoborneol in channel catfish (Ictalurus punctatus)

Off-flavor, due to organoleptic compounds such as 2-methylisoborneol (MIB), is the single largest detriment to the harvest, production and profit from the channel catfish aquaculture industry of the Southeastern United States. Methods to increase the metabolism and/or elimination of compounds like MIB would provide a means towards improving catfish rearing practices. Previous studies indicated one or more forms of cytochrome P450 monooxygenase (CYP) may be involved in the biotransformation and elimination of specific organoleptic compounds, such as 2-methylisoborneol (MIB). In order to determine the role of CYP in the elimination of MIB, various compounds that have been shown to modulate cytochrome P450 expression in catfish were administered before and after exposure to ¹⁴C-MIB. Uptake and elimination was monitored in fish over 24 and 48 h, respectively. Pretreatment with clofibric acid (100 mg kg^–1-gavage) which induces a CYP2K-like isoform, and ethanol (1.0% v/v-aqueous) a CYP2 represser, alone and with enhanced temperature (added 10 °C) failed to affect uptake of MIB. Pretreatment with these compounds and conditions also failed to enhance elimination of MIB from channel catfish. However, when fish were treated with 1.0% ethanol after MIB exposure (i.e., during depuration), beta elimination halflives were changed from 144±35 to 71±13 h. in sexually mature animals but unchanged (191±113) in juveniles. The failure of CYP-modulating agents to alter MIB elimination in catfish suggests MIB may not readily undergo Phase I oxidation via CYP. The enhanced elimination of MIB in adults by ethanol warrants further study as to its potential use in aquaculture in purging MIB and related compounds prior to fish processing.     

Effects of dietary docosahexaenoic acid (22:6n‐3) and arachidonic acid (20:4n‐6) on the growth,survival, stress resistance and fatty acid composition in black sea bass Centropristis striata (Linnaeus 1758) larvae

The objectives of this study were to determine the effects of the dietary docosahexaenoic acid (DHA) to arachidonic acid (ARA) ratio on the survival, growth, hypersaline stress resistance and tissue composition of black sea bass larvae raised from first feeding to metamorphic stages. Larvae were fed enriched rotifers Brachionus rotundiformis and Artemia nauplii containing two levels of DHA (0% and 10% total fatty acids=TFA) in conjunction with three levels of ARA (0%, 3% and 6% TFA). On d24ph, larvae fed the 10:6 (DHA:ARA) treatment showed significantly (P<0.05) higher survival (62.3%) than larvae fed 0:0 (DHA:ARA) (27.4%). Notochord length and dry weight were also significantly (P<0.05) greater in the 10:6 (DHA:ARA) treatment (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline (65 g L⁻¹) challenge, no significant differences (P>0.05) were observed in the median survival time (ST50) between larvae fed 10% DHA (ST50=25.6 min) and larvae fed 0% DHA (ST50=18.2 min). The results suggested that black sea bass larvae fed prey containing 10% DHA with increasing ARA within the range of 0–6% showed improved growth and survival from first feeding through metamorphic stages.     

Effects of dietary chlorogenic acid on growth,flesh quality and serum biochemical indices of grass carp (Ctenopharyngodon idella)

The study was to investigate effects of dietary chlorogenic acid (CGA) on growth performance, flesh quality and serum biochemical indices of grass carp (95.1 ± 0.3 g) (Ctenopharyngodon idella) fed seven different diets, including control diet, Eucommia ulmoides (EU)‐supplemented diet (20 g kg^–1) and CGA‐supplemented diets containing 100, 200, 400, 600 and 800 mg/kg CGA. Contents of collagen and alkaline‐insoluble collagen in muscle and skin were significantly increased by dietary CGA and EU (p < .05). Total essential amino acids (TEAA) and total amino acids (TAA) in muscle of grass carp fed EU diet or 400, 600 and 800 mg/kg CGA diet were significantly higher than those of fish fed control diet and 100 and 200 mg/kg CGA diet (p < .05). Fish fed 200–800 mg/kg CGA showed significantly lower muscle crude lipid content than EU, control and 100 mg/kg CGA groups (p < .05). Fish fed CGA‐supplemented diets (100–800 mg/kg) had significantly higher muscle fibre density and lower muscle fibre diameter than control group (p < .05). In conclusion, supplementation of CGA improved flesh quality of grass carp, and supplemental level of CGA for improving flesh quality and growth was estimated to be 400 mg/kg diet.