Protein requirement of jundia fingerlings, Rhamdia quelen, at two dietary energy concentrations

A feeding trial was carried out where five protein concentrations [26%, 29%, 33%, 37%, and 41% crude protein (CP)] were fed to jundia fingerlings at two dietary energy concentrations [3200 and 3650 kcal metabolizable energy (ME)/kg diet] to establish the protein requirement for this species. Triplicate groups of 23 fish (average weight 1.52±0.34 g) were each stocked in 120-l aquaria and fed semipurified diets twice a day to apparent satiation. After 90 days, fish weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), energy retention (ER), apparent net protein utilization (ANPU), feed consumption (% body weight) and body composition (crude protein, fat, and ash) were affected by diet composition. Weight gain, SGR, FE, ANPU and ER increased (P<0.05) as the dietary protein concentration increased up to 33% and 37%, for fish fed diets containing 3650 and 3200 kcal, respectively. A significant interaction between dietary protein and energy was observed for WG, SGR, and PER. Feed consumption was not affected by dietary energy concentration, but decreased with increasing dietary protein concentration (P<0.05). Body fat decreased as dietary protein increased at both energy concentrations, but was higher in fish fed the 3650 kcal diet. The opposite was observed for body protein, ER, and ANPU (P<0.05). Our findings demonstrate that jundia presents dietary protein sparing effect when the energy concentration increases from 3200 to 3650 kcal/kg. Jundia protein requirement, determined by the broken line method, is between 32.6% and 37.3% CP, depending on dietary energy concentration.     

饲料蛋白质和脂肪水平对牛蛙生长性能的影响

为研究饲料中不同蛋白质和脂肪水平对牛蛙生长、体组成和肝脏健康的影响,以红鱼粉、豆粕和酪蛋白为蛋白源,鱼油和豆油为主要脂肪源,α-淀粉为主要糖源,微晶纤维素为填充剂,并补充无机盐和维生素等配制实验饲料。实验设3个蛋白水平(35%、40%和45%),每个蛋白水平下设4个脂肪水平(4%、7%、10%和13%),共12种饲料,饲料可利用能变化范围为12.4~17.8 kJ/g,蛋白能量比变化范围为21.9~32.0 mg/kJ。每种饲料设置3个重复,每个水族缸放养12只牛蛙[初始平均体质量为(91.5±1.1)g],每日饱食投喂2次,实验周期56 d。结果发现,饲料蛋白质和脂肪水平对牛蛙的存活率无显著影响,而13%脂肪组的牛蛙肝脏出现颜色不均一和肝体脆化无韧性的现象。饲料蛋白质和脂肪水平显著影响牛蛙的增重率、特定生长率、摄食率、饲料效率和蛋白质效率。其中,40%蛋白组牛蛙的增重率和特定生长率显著高于35%蛋白组,与45%蛋白组无显著差异。随着蛋白质水平的升高,饲料效率显著升高,而摄食率和蛋白质效率显著降低。随着脂肪水平的升高,增重率、特定生长率和摄食率显著升高,饲料效率、蛋白质效率和氮保留率无显著差异。饲料脂肪水平与牛蛙全体的脂肪含量和总能水平正相关,但不影响牛蛙全体的蛋白质含量。随着饲料脂肪水平的升高,牛蛙肝脏丙二醛含量显著升高,过氧化氢酶和脂蛋白酯酶活力先升高后降低。研究表明,牛蛙饲料适宜的蛋白质和脂肪水平分别为40%和7%,适宜蛋白能量比为27.7 mg/kJ。     

Growth,feed utilization and body composition of African bonytongue,Heterotis niloticus,fingerlings fed diets containing various protein and lipid levels

In order to evaluate the effects of dietary protein and lipid levels on the growth, feed utilization and body composition of Heterotis niloticus fingerlings, a factorial experiment with three replicates was conducted. Six experimental diets containing three crude protein levels (28%, 32% and 36%) and two crude lipid levels (6% and 13%) were tested. Heterotis niloticus (2.34 g) were fed with the diets to apparent satiation, twice a day. For 56 days, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein retention (PR) were significantly affected by dietary protein and dietary lipid levels respectively (P<0.01). The highest WG, SGR and FE were observed for fingerlings fed the diet containing 36% protein and 6% lipid, but no significance difference was found between groups fed with the following diets: P28L13 (28% protein and 13% lipid), P32L6, P32L13 and P36L13. A significant interaction between dietary protein and lipid was observed for WG, SGR, FE and PR. The whole‐body protein, lipid, moisture and ash content were not significantly affected by dietary lipid levels, but body protein and lipid content were significantly affected by dietary protein. The dietary protein‐sparing effect was clearly demonstrated when the dietary energy of lipid increased from 17 to 19.6 kJ g^?1 at 28% crude protein on H. niloticus.     

不同小麦淀粉和脂肪水平对大黄鱼的生长性能、饲料利用及糖代谢关键酶活力的影响

为探讨饲料中添加不同小麦淀粉和脂肪水平对大黄鱼幼鱼生长、饲料利用以及糖代谢关键酶活力的影响,进行了为期8周的生长实验。设计了3个小麦淀粉水平(5%、10%和30%)和2个脂肪水平(5%和10%)的3×2的两因子实验,配制了6种等氮的饲料,分别喂养平均体质量为(6.75±0.12)g的大黄鱼幼鱼。结果显示,饲料中小麦淀粉和脂肪水平对大黄鱼增重率(WG)、特定生长率(SGR)、饲料效率(FE)、成活率(SR)、肝体比(HSI)和肥满度(CF)无显著交互作用,对脏体比(VSI)有显著交互作用。在同一脂肪水平下,淀粉水平为30%组WG和SGR显著高于10%淀粉组。不同小麦淀粉和脂肪水平对肝糖原含量无显著交互作用,而对肌糖原含量有显著交互作用,在饲料脂肪水平为5%时,30%小麦淀粉水平下的肝糖原含量显著高于10%和20%淀粉水平,10%淀粉水平下的肌糖原含量显著高于20%和30%淀粉水平;在脂肪水平为10%时,10%淀粉水平下的肝糖原含量显著高于20%和30%淀粉水平,而30%小麦淀粉水平下的肌糖原含量显著高于10%和20%淀粉水平。小麦淀粉和脂肪水平对血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)、总胆固醇(TC)和葡萄糖(GLU)含量无显著交互作用,对总蛋白(TP)和甘油三酯(TG)交互作用显著。不同小麦淀粉和脂肪水平对肝脏脂肪酶活性有显著的交互作用,对淀粉酶活性无显著交互作用;同一脂肪水平下,脂肪酶的活性随着淀粉水平的升高而升高,同一饲料淀粉水平下,饲料脂肪水平为10%组的脂肪酶活性显著高于5%组。不同小麦淀粉和脂肪水平对肝脏丙酮酸激酶(PK)的活性有显著的交互作用,而对葡萄糖激酶(GK)、磷酸果糖激酶(PFK)、磷酸烯醇式丙酮酸羧激酶(PEPCK)、1,6-二磷酸果糖酶(FBPase)和6-磷酸葡萄糖酶(G6Pase)的活性均无显著交互作用。研究表明,当饲料脂肪水平为5%时,大黄鱼能够通过调节糖酵解关键酶活性及肝糖原含量来维持血糖平衡,改善对小麦淀粉的利用能力;而当脂肪水平为10%时,大黄鱼对小麦淀粉的利用能力降低。     

Influence of Ulva meal on growth, feed utilization, and body composition of juvenile Nile tilapia (Oreochromis niloticus) at two levels of dietary lipid

A nutrition trial was conducted to investigate the effects of dietary lipid levels and supplemental Ulva meal on growth performance, feed efficiency, nutrient utilization, and body composition of juvenile Nile tilapia, Oreochromis niloticus. Four isonitrogenous (CP 40%) diets containing 0% and 5% Ulva meal were formulated to contain 10% (low-lipid; LL) and 20% (high-lipid; HL) crude lipid. Triplicate groups of fish (~10 g) were fed to apparent satiation three times daily for 16 weeks. Fish fed 5% Ulva meal showed an increased growth performance (P < 0.05) compared with fish fed non-Ulva supplemented diets, irrespective of dietary lipid level. In particular, the incorporation of Ulva meal improved specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER). Feeding fish 5% Ulva meal diets resulted in significantly lower carcass lipid content. The results indicate that 5% inclusion of Ulva meal at both dietary lipid levels improves growth performance, feed efficiency, nutrient utilization, and body composition of Nile tilapia.     

Effects of dietary macronutrient level and feeding frequency on growth and body composition of juvenile rockfish (Sebastes schlegeli)

An 8-week feeding experiment was conducted to investigate the effects of different dietary macronutrient level and feeding frequency on the growth, feed utilization, and body composition of juvenile rockfish. Triplicate groups of fish (body weight of 4.1 g) were fed the experimental diets containing either high levels of carbohydrate (HC, 35%), lipid (HL, 13%), or protein (HP, 55%) at different feeding frequencies (twice daily, once daily, and once every 2 days). Weight gain was affected by feeding frequency but not by dietary composition. Weight gain of fish fed the diets once every 2 days was significantly (P < 0.05) lower than that of other groups. Daily feed intake and energy intake were affected by both dietary composition and feeding frequency. Daily feed intake of fish fed the HC diet was significantly (P < 0.05) higher than that of fish fed the HL and HP diets at the same feeding frequency. Feed efficiency and protein efficiency ratio were affected by both dietary composition and feeding frequency and decreased with increasing feeding frequency in the same dietary composition. Feed efficiency and protein efficiency ratio of fish fed the HC diet were significantly (P < 0.05) lower than those of fish fed the HL diet at the same feeding frequency. Whole-body lipid content of fish fed the HL diet was significantly (P < 0.05) higher than that of fish fed the HC and HP diets at the same feeding frequency. These results indicate that an increase of dietary lipid level compared with dietary carbohydrate level may have the advantage of a protein-sparing effect at same feeding frequency, and a once-daily feeding regime is more effective than twice daily or one feeding every 2 days to improve growth performance of juvenile rockfish grown from 4 to 21 g.     

Dietary threonine requirement of juvenile large yellow croaker,Larmichthys crocea

A feeding trial was conducted to determine the dietary threonine requirement of juvenile large yellow croaker (Larmichthys crocea). Six diets were formulated containing 45% crude protein with six graded levels of threonine (0.71–2.46% in about 0.35% increment). Each diet was randomly assigned to triplicate groups of 60 juvenile fish (initial body weight 6.00 ± 0.10 g). Fish were fed twice daily (05:00 and 16:30) to apparent satiation for 8 weeks. The result indicated that significant difference was observed in the weight gain among all treatments. Specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER) and nitrogen retention (NR) increased with increasing levels of threonine up to 1.75% diet (P < 0.05), and thereafter, declined. No significant differences in body dry matter, crude protein, crude lipid or ash content were found among dietary treatments. Theronine contents of fish muscle were significantly affected by dietary threonine levels (P < 0.05). Fish fed the diet with 0.71% threonine showed the lowest threonine content (2.94%) in fish muscle, while fish fed the diet with 1.75% threonine had the highest value (3.16%). Other essential amino acid contents of muscle were not significantly different among the dietary treatments. On the basis of SGR, FE or NR, the optimum dietary threonine requirements of juvenile L. crocea were estimated to be 1.86% of diet (4.13% of dietary protein), 1.90% of diet (4.22% of dietary protein) and 2.06% of diet (4.58% of dietary protein), respectively, using second‐order polynomial regression analysis.     

玉米蛋白粉替代鱼粉对大菱鲆摄食、生长及体组成的影响

以鱼粉和玉米蛋白粉作蛋白源,配制6种等氮等能的饲料。其中5种饲料(C0、C12、C25、C38和C50.5)分别含有0%、12%、25%、38%和50.5%的玉米蛋白粉以替代相应的鱼粉蛋白。其余1种饲料(C50.5CAA)是在饲料C50.5基础上补充1.8%晶体氨基酸混合物(L-lysine:1.2%,L-arg:0.6%)。经7周的生长试验,结果表明随着饲料中玉米蛋白粉替代水平的升高,大菱鲆(12.51±0.02)g的摄食率、特定生长率、饲料效率和蛋白质效率均显著下降。饲料中玉米蛋白粉含量为50.5%时,大菱鲆摄食率显著低于其他处理组(P<0.05)。当饲料中玉米蛋白粉含量超过25%时,大菱鲆特定生长率显著低于对照组(C0)(P<0.05)。当饲料中玉米蛋白粉含量超过38%时,饲料效率和蛋白质效率与对照组(C0)相比显著下降(P<0.05)。C50.5CAA组的摄食率、特定生长率和蛋白质效率与C50.5组相比都有升高的趋势,但差异不显著。而饲料中添加晶体氨基酸显著提高了大菱鲆的饲料效率(P<0.05)。饲料中玉米蛋白粉替代鱼粉对大菱鲆鱼体水分、粗蛋白、粗脂肪及灰分含量均无显著影响。饲料中玉米蛋白粉替代鱼粉对大菱鲆血清甘油三酯和尿素氮含量也不产生显著影响,然而,随着饲料中玉米蛋白粉含量升高,血清总胆固醇含量显著下降(P<0.05)。     

卵形鲳鲹幼鱼饲料中适宜蛋白能量比的研究

以鱼粉、豆粕为蛋白源,豆油、鱼油为脂肪源,配制9种不同蛋白能量水平的饲料,蛋白质3个水平(38%、43%、49%),每个蛋白水平设3个脂肪梯度(6%、10%、14%),其蛋白能量比为19.3～27.4mg/kJ。卵形鲳鲹初始质量为(25.02±0.16)g,每个处理设3个重复,每个网箱(1.5 m×1.0 m×2.0m)放养卵形鲳鲹苗20尾,养殖试验持续8周。结果显示,卵形鲳鲹特定生长率随饲料蛋白水平的升高而显著升高(P<0.05)。投喂含43%或49%蛋白质、6%脂肪饲料的卵形鲳鲹表现出较好的特定生长率。饲料中不同的脂肪水平未表现出蛋白质节约效应,较高的脂肪水平反而抑制了卵形鲳鲹的特定生长率、饲料效率和蛋白质效率。卵形鲳鲹鱼体蛋白和脂肪含量分别随饲料蛋白质和脂肪水平的上升而显著升高(P<0.05)。在该试验条件下,卵形鲳鲹幼鱼饲料中最适蛋白质、脂肪水平和蛋白能量比分别为43%、6%和24.4 mg/kJ。     

Effect of dietary protein levels on growth,feed utilization and carcass composition of endangered bagrid catfish Horabagrus brachysoma (Gunther 1864) fingerlings

An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg^?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg^?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg^?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg^?1 diet.     

The influence of feeding rate on growth, feed efficiency and body composition of juvenile grass carp (Ctenopharyngodon idella)

An 8 weeks growth study was conducted to estimate the optimal feeding rate for juvenile grass carp (3.08±0.03 g, mean ± SD). Fish were fed with a casein purified diet (360 g protein, 56 g lipid and 3000 kcal total energy/kg dry diet) at six feeding rates: 1.0, 1.5, 2.0, 2.5, 3.0, 3.5% body weight per day (BW d⁻¹). Each feeding rate was randomly assigned to three tanks of fish with 30 fish per tank (50W × 50H × 100L, cm). Fish were maintained in recirculating systems at a water temperature of 24.97±2.23 °C and were fed four times per day. After 2 weeks, fish fed on 3.5% BW d⁻¹ could not finish the diet and this treatment was cut-off. Analysis of variance showed that growth performance was significantly (p<0.05) affected by different feeding rates. The nutrient compositions of whole body, muscle and liver were also significantly different among treatments. The body weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), apparent digestibility coefficiency (ADC), retention of protein (PR), mesenteric fat index, body moisture and protein content were significantly (p<0.05) affected by feeding rate. The WG, SGR and digestion rate were highest at 2% BW d⁻¹, although the FE and PER decreased with increasing feeding rate. Broken line analysis on specific growth rate indicated that the optimum feeding rate of juvenile grass carp is 1.97% body weight day⁻¹.     

Optimum dietary phosphorus level of juvenile Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> reared in the recirculating system

ABSTRACT:   An 8-week feeding trial was conducted to determine the optimum dietary phosphorus level of juvenile Japanese flounder Paralichthys olivaceus reared in the recirculating system. The basal diet containing 0.33% total phosphorus (TP) was supplemented with NaH₂PO₄·H₂O to provide 0.33, 0.51, 0.71, 0.94, 1.10 and 2.12% TP for the experimental diets. Fish averaging 2.0 ± 0.04 g (mean ± SD) were fed in triplicate groups with the experimental diets for 8 weeks. After 8 weeks, fish fed the 0.51% TP diet showed significantly higher weight gain (WG), feed efficiency (FE), specific growth rate (SGR), and protein efficiency ratio (PER) than those fed the 0.33% and 2.12% TP diets ( P  < 0.05). Meanwhile, no difference was observed in WG, FE, SGR and PER of fish fed the 0.51, 0.71, 0.94 and 1.10% TP diets. Fish fed the 0.33% TP diet showed phosphorus deficiency symptoms such as poor growth and a deformed head by the end of 8 weeks. Ash and phosphorus contents of bone increased with the increase of dietary phosphorus concentrations. anova test, the quadratic regression analysis, and the broken line analysis suggested that the optimum dietary phosphorus level could be between 0.45 and 0.51% TP for maximum WG in juvenile Japanese flounder.     

Optimum feeding rates in juvenile olive flounder,Paralichthys olivaceus,at the optimum rearing temperature

Two feeding trials were carried out to determine the optimum feeding rates in juvenile olive flounder, Paralichthys olivaceus, at the optimum rearing temperature. Fish averaging 5.0 ± 0.11 g (mean ± SD) in experiment 1 and 20.2 ± 0.54 g (mean ± SD) in experiment 2 were fed a commercial diet at the feeding rates of 0%, 3.0%, 4.0%, 4.25%, 4.5% and 4.75% body weight (BW) day^?1 and satiation (5.52% BW day^?1) in experiment 1 and 0%, 1.0%, 2.0%, 3.0% and 3.5% BW day^?1 and satiation (4.12% BW day^?1) in experiment 2 at 20 ± 1 °C. Both feeding trials lasted for 2 weeks. Results from experiment 1 indicated that weight gain (WG) and specific growth rate (SGR) of fish fed to satiation were significantly higher than those of fish fed at other feeding rates while feed efficiency (FE) and protein efficiency ratio (PER) of fish fed at 4.25% BW day^?1 were significantly higher than those of fish fed to satiation and fish fed at 3.0% BW day^?1 (P < 0.05). In experiment 2 WG, SGR and PER leveled out after the feeding rate of 3.5% BW day^?1 whereas FE reached a plateau at 3.0% BW day^?1. anova of FE indicated that the optimum feeding rates in 5.0 and 20 g juvenile olive flounder could be 4.25% and 3.0% BW day^?1, respectively. Broken line analysis of WG suggested the optimum feeding rates of 5.17% and 3.47% BW day^?1 in 5.0 and 20 g fish, respectively. Therefore, these results indicated that the optimum feeding rates could be >4.25 but <5.17% BW day^?1 for 5.0 g, and it could be >3.0 but <3.47% BW day^?1 for 20 g size of juvenile olive flounder at the optimum rearing temperature.     

Optimal dietary carbohydrate to lipid ratio for juvenile yellowfin seabream (Sparus latus)

A growth experiment was conducted to determine the optimal carbohydrate‐to‐lipid (CHO: L) ratio for juvenile yellowfin seabream cultured in 340‐L indoor recirculating tanks. Seven isonitrogenous (450 g kg⁻¹ dietary protein) and isoenergetic (14.1 MJ kg⁻¹) diets with increasing CHO: L ratios (0.03–5.09 g: g) were fed to triplicate groups of 30 fish with an initial weight of 4.91 g for 56 days. Fish were fed to satiation twice a day and the water temperature ranged between 28 and 31.7 °C during the experimental period. Survival was high in all the groups and was not affected by dietary treatments. Best weight gain (WG) and specific growth rate (SGR) were observed in fish fed diets with CHO: L ratios of 0.29 and 0.72, which were not significantly different from that of 0.03, 1.26 and 1.92, but apparently higher than that of 3.22 and 5.09. Feed efficiency (FE), protein efficiency ratio (PER) and protein production value (PPV) followed the same general pattern as WG and SGR. Highest level of energy production value (EPV) was found in fish fed diets with CHO: L ratio of 0.72. Proximate compositions of fish whole body and tissues were markedly affected by dietary CHO: L ratios. Whole body, muscle and liver lipid increased as CHO: L ratios decreased, whereas moisture contents were reduced. Dietary CHO: L ratios had no significant effect on protein content in whole body and muscle. Plasma total cholesterol levels of fish fed diets with CHO: L ratios less than 0.72 were significantly higher than those of the other groups. Triacylglyceride levels decreased linearly as dietary CHO: L ratios increased. Viscerosomatic index (VSI) significantly increased as dietary CHO: L ratios decreased. Intraperitoneal fat ratio (IPF) of fish fed diets with CHO: L ratios less than 1.92 were significantly higher than those fed CHO: L ratios of 3.22 and 5.09. Hepatosomatic index (HSI) did not vary between the test diets. Based on second‐order polynomial regression analysis of WG against dietary carbohydrate and lipid levels, 84.1 g kg⁻¹ of carbohydrate and 136.3 g kg⁻¹ of lipid, corresponding to a CHO: L ratio of 0.62, in a diet holding 450 g kg⁻¹ of crude protein and 14 KJ g⁻¹ of metabolizable energy, proved to be optimal for juvenile yellowfin seabream.     

Influence of dietary concentrations of protein,lipid and carbohydrate on growth,protein and energy utilization,body composition,and plasma titres of growth hormone and insulin-like growth factor-1 in non-transgenic and growth hormone transgenic coho salmon,Oncorhynchus kisutch (Walbaum)

This study compared the ability of juvenile non-transgenic (NT) and transgenic growth hormone (T; gene construct OnMTGH1) coho salmon (Oncorhynchus kisutch) to metabolically utilize energy from lipid and carbohydrate for growth at two dietary protein concentrations. Triplicate groups of size-matched (initial weight, 28.2–29.1 g) NT and T salmon held in 10.5–10.8 °C well water on a natural phototocycle (12.25 h → 8.25 h) were each fed one of four isoenergetic (~ 17.5 MJ of digestible energy (DE)/kg) dry diets twice daily to satiation for 83 days. These diets contained 340 g (LP) or 430 g (HP) of estimated digestible protein (DP)/kg and either 123 g (LL) or 164 g (HL) of estimated digestible lipid (DL)/kg at each DP level (dry weight basis). Estimated digestible carbohydrate (DCHO) concentrations ranged from 45 to 269 g/kg to equalize dietary DE. Under the preceding conditions 46–66% of NT and 18.7–27.5% of T coho, depending upon diet treatment, exhibited no growth or lost weight during the study. NT coho are known to grow slowly or lose weight between the fall equinox and winter solstice but this was unexpected for T coho. Considering all fish T coho, regardless of diet treatment, exhibited significantly higher specific growth rates (SGR) than NT fish due to enhanced feed intake, feed and protein (gross and available deposited) utilization and generally improved available energy utilization. Diet treatment did not affect the growth performance of T fish. Within NT fish, the HP diets supported best gross and available protein and energy utilization. SGR values for growing fish (F_G) only followed identical trends to those for all fish in relation to diet treatment. Regardless of fish genotype, terminal hepatosomatic indices for F_G were directly related to dietary DCHO content and maximum values were noted in NT fish fed LP–LL (significantly higher than observed in NT or T fish fed HP–HL). Final whole body protein concentrations adjusted for dissimilar fish size were higher in T fish fed HP–HL than in T fish fed LP diets and NT fish fed LP–LL. This was also true for T fish fed HP–LL versus T fish fed the LP diets. Within HP groups, whole body lipid and energy contents were generally higher in NT versus T fish whereas within the LP groups energy content was significantly higher in T versus NT fish and was highest in T fish fed LP–LL. Terminal plasma titres for GH and IGF–1 (all fish) were significantly higher in T than in NT fish and were generally uninfluenced by diet treatment. Non-growing NT and T fish had elevated GH relative to NT and T fish that grew. Also, GH was higher in growing T fish relative to growing NT fish whereas the opposite was true in non-growing fish. Plasma IGF-1 levels were higher in growing NT and T fish than in their respective non-growing counterparts. Within F_G only, IGF-1 levels were higher in T versus NT fish.It is concluded that T coho have enhanced ability to effectively utilize DE from DCHO relative to NT fish especially when DP is near the bottom of the optimal range and DL is concurrently suboptimal for NT fish. This is likely due to the elevated titres of GH, IGF-1 and 3,5,3′-triiodo-l-thyronine (measured in another study) in T fish. Also, the enhanced ability of T fish to store energy under these dietary conditions suggests enzymatic improvements in their anaerobic and aerobic metabolism of glucose.     

大规格鲈鱼(Lateolabrax japonicas)对饲料中花生四烯酸的需求量

选用初始体重(207.16±0.72) g 的鲈鱼(Lateolabrax japonicas)为研究对象,研究大规格鲈鱼对花生四烯酸(Arachidonic acid,ARA)的最适需求量。通过在基础饲料中添加 ARA-纯化油,制成ARA 含量分别为0.05%、0.22%、0.37%、0.60%、1.38%及2.32%(占饲料干重)的6组等氮等能的实验饲料,进行为期84 d 的生长实验。实验结束后,通过测定鲈鱼生长、体成分、抗氧化及肝脏健康等指标综合评价鲈鱼对饲料中花生四烯酸的需求量。结果显示,鲈鱼成活率在不同处理组之间无显著差异(P>0.05);鲈鱼的特定生长率(SGR)随着饲料中 ARA 含量的升高,呈先升高后相对平稳的趋势(P<0.05),且在 ARA 含量为0.37%饲料组出现最大值,饲料效率(FE)呈现出与特定生长率相同的趋势;饲料中不同 ARA 含量对鲈鱼的肝体比(HSI)、脏体比(VSI)、肥满度(CF)均无显著性影响(P>0.05);鱼体粗脂肪含量随着饲料 ARA 含量升高呈先减少后增加的趋势,粗蛋白含量则呈现出相反趋势;随着饲料 ARA 含量的升高,血清和肝脏中超氧化物歧化酶(SOD)活力呈现先升高后降低的趋势(P<0.05),肝脏和血清中丙二醛(MDA)含量则呈现先降低后升高的变化趋势(P<0.05);血清中谷草转氨酶和谷丙转氨酶活性均在0.37%ARA 水平时显著低于对照组(P<0.05)。以特定生长率与饲料效率作为评定指标,经折线模型分析得出,(207.16±0.72) g 规格的鲈鱼对饲料中 ARA 的最适需求量均为饲料干重的0.37%。     

Optimum Dietary Protein Level and Protein‐to‐energy Ratio for Growth of Juvenile Parrot Fish,Oplegnathus fasciatus

An 8‐wk feeding trial was conducted to estimate the optimum dietary protein level and protein‐to‐energy (P/E) ratio in juvenile parrot fish, Oplegnathus fasciatus. Eight experimental diets were formulated with two energy levels and four protein levels for each energy level. Diets containing crude protein (CP) at 35, 40, 45, and 50% had either 12.5 or 14.6 kJ/g of energy. Fish averaging 7.1 ± 0.06 g (mean ± SD) were fed one of the experimental diets for 8 wk. At the end of the feeding trial, weight gain (WG) of fish fed 45 and 50% CP in the 12.5 kJ/g diet was significantly higher than fish fed the 35% CP diet (P < 0.05). WG of the fish fed 45 and 50% CP in the 14.6 kJ/g diet was significantly higher than fish fed the 35 and 40% CP diets (P < 0.05). Fish fed the 14.6 kJ/g diet had a higher WG compared with fish fed the 12.5 kJ/g diet at all CP levels. Feed efficiency (FE) and specific growth rate (SGR) showed a similar trend to the WG. WG, FE, and SGR improved with increasing dietary protein levels up to 45% and remained constant at 50% CP for both energy levels. However, protein efficiency ratio was negatively related to dietary protein levels. The results suggested that the optimum level of protein and the optimum P/E ratio for juvenile parrot fish should be 45% and 31.1 mg protein/kJ, respectively, in a diet containing 14.6 kJ/g energy.     

Effect of Dietary Prebiotic Inulin on Growth Performance,Intestinal Microflora,Body Composition and Hematological Parameters of Juvenile Beluga,Huso huso (Linnaeus, 1758)

Use of prebiotics, nondigestible dietary ingredients that beneficially affect the host by selectively stimulating the growth of and/or activating the metabolism of health‐promoting bacteria in the intestinal tract, is a novel concept in aquaculture. An 8‐week feeding experiment was conducted to investigate the effects of dietary prebiotic inulin on growth performance, intestinal microflora, body composition and hematological parameters of juvenile beluga, Huso huso. Three replicate groups of fish (initially averaging weight as group 16.14 ± 0.38 g) were fed diets containing prebiotic inulin levels ranging from 1 to 3%. The basal diet contained 3% cellulose. Fish were fed to apparent satiation and growth performance was monitored. The results of linear regression showed that there was a negative relationship between some performance indices including weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), energy retention (ER), feed efficiency (FE), protein retention (PR), and supplementation level of inulin, which indicated that inulin is not appropriate for supplementation in the diet of beluga. At the end of trial, in both basal and inulin groups, the total count of intestinal bacteria decreased within the second 4 weeks, but the intestinal lactic acid bacteria (LAB) increased in the 1% inulin group. These changes were not, however, reflected in the survival rate of the fish, although survival was higher compared to other groups.     

Effects of dietary protein to energy ratios on growth and body composition of juvenile Japanese seabass, Lateolabrax japonicus

A growth experiment was conducted to determine the optimal dietary protein to energy (P/E) ratio for juvenile Japanese seabass (initial average weight 6.26±0.10 g). Nine practical diets were formulated to contain three protein levels (36%, 41% and 46%), each with three lipid levels (8%, 12% and 16%), in order to produce a range of P/E ratios (from 19.8 to 28.6 mg protein kJ⁻¹). Each diet was randomly assigned to triplicate groups of 60 fish in sea floating cages (1.5×1.5×2.0 m). Fish were fed twice daily (06:30 and 16:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 26.5 to 32.5 °C, the salinity from 32‰ to 36‰ and dissolved oxygen content was approximately 7 mg l⁻¹ during the experimental period. The results showed that the growth was significantly affected by dietary P/E ratio (P<0.05). Fish fed the diets with 46% protein (12% and 16% lipid, P/E ratio of 26.7 and 25.7 mg protein kJ⁻¹) had the highest specific growth rates (SGR) (4.26 and 4.24% day⁻¹). However, fish fed the diet with 41% protein and 12% lipid showed comparable growth (4.20% day⁻¹), and had higher protein efficiency ratio (PER), protein productive value (PPV) and energy retention than other groups (P<0.05). No significant differences in survival were found among dietary treatments. Carcass lipid content positively correlated with dietary lipid level irrespective of protein level and inversely correlated with carcass moisture content. Carcass protein and ash contents increased with increasing dietary lipid at each protein level. These results suggest that the diet containing 41% protein and 12% lipid with P/E of 25.9 mg protein kJ⁻¹ is optimal for Japanese seabass.     

黄鳍鲷幼鱼对几种不同糖源的利用

本研究用来评价黄鳍鲷幼鱼对饲料中葡萄糖、麦芽糖、糊精、玉米淀粉和预糊化玉米淀粉的利用。本试验饲料为6种等氮(粗蛋白:45%,干重)等脂(粗脂肪:9%,干重)的半纯化饲料,其中对照组糖源为纤维素。每种饲料设3个平行。试验鱼初始体重为(3.57±0.13)g(平均值±均差)。试验鱼饲养在含18个水族箱的循环系统中。水温保持在(27±1)℃。试验周期为8周。本试验用来评价黄鳍鲷幼鱼对饲料中不同糖源利用的指标为生长指标、饲料效率、蛋白质效率和肝脏的6-磷酸葡萄糖脱氢酶、苹果酸脱氢酶、异柠檬酸脱氢酶和葡萄糖-6-磷酸脱氢酶。试验结果表明,黄鳍鲷幼鱼体增重、特定生长率、肝体比、肠系膜脂肪体比、饲料效率、蛋白质效率、肝脂肪合成有关酶活性和全鱼、肌肉、肝脏组成均受到饲料中不同糖源的显著影响。预糊化玉米淀粉和麦芽糖组比其它糖源组显著具有更好的体增重和特定生长率,但与对照组没有显著性差异。黄鳍鲷幼鱼生长和体增重与饲料中糖源的复杂性没有相关性。饲喂预糊化淀粉和对照饲料鱼的饲料效率和蛋白质效率显著比其它组高。饲料中糖的添加增加了黄鳍鲷幼鱼的肝体比,但对照组肝体比与糊精组,玉米淀粉组没有显著性差异。预糊化玉米淀粉组肠系膜脂肪体比比其它饲料组要高。结论:基于体增重和特定生长率为指标,饲料中添加25%预糊化玉米淀粉和麦芽糖可以提高黄鳍鲷幼鱼的生长。另外,玉米淀粉预糊化显著提高了黄鳍鲷对玉米淀粉的利用。