裂壶藻对津新鲤(Cyprinus carpio var. Jian)生长、血液非特异性免疫指标及抗病力的影响

选用初始体重为(26.77±1.56)g的津新鲤(Cyprinus carpio var.Jian) 540尾,随机分为6组,每组3个重复,分别投喂含0、0.40％、0.80％、1.20％、1.60％和2.00％裂壶藻的等氮等能饲料,饲养56 d,探讨饲料中不同水平的裂壶藻对津新鲤生长、血液非特异性免疫指标及抗病力的影响.结果显示,在0.80％裂壶藻水平组中,增重率和特定生长率均显著提高(P＜0.05),肥满度则在1.20％水平组中达到最大值(P＜0.05),各组间成活率差异不显著(P＞0.05).不同水平的裂壶藻均可以显著提高津新鲤的抗氧化能力,其中过氧化氢酶、总超氧化物歧化酶和谷胱甘肽的含量均呈先上升后下降的趋势,且分别在1.20％、0.80％和1.20％组中达到最高(P＜0.05);而丙二醛含量呈先下降后上升的趋势,在0.80％组中达最低(P＜0.05).不同水平的裂壶藻均可以显著提高津新鲤的非特异性免疫力,溶菌酶呈先上升后下降的趋势,其中1.20％组活性最高(P＜0.05).一氧化氮含量随裂壶藻水平增加而增加,各添加组含量均显著高于对照组(P＜0.05).谷草转氨酶/谷丙转氨酶在0.80％组中达到最小值(P＜0.05).随着裂壶藻水平的增加,津新鲤血细胞呼吸爆发活性和免疫保护率得到显著提高,感染嗜水气单胞菌后的累计死亡率则显著降低(P＜0.05),其中,以0.80％组最佳.综合生长、血液非特异性免疫指标和抗病力来分析,饲料中裂壶藻的适宜添加水平为0.80％-1.20％.     

Replacement of Fish Oil with Linseed Oil or Soybean Oil in Feeds for Japanese Seabass,Lateolabrax japonicus: Effects on Growth Performance,Immune Response,and Tissue Fatty Acid Composition

A 66‐d feeding experiment was conducted to investigate the utilization of vegetable oils in Japanese seabass (initial weight: 10.09 ± 0.70 g). In experimental diets, linseed oil (LO) or soybean oil (SO) was used to replace 1/3, 2/3, and 3/3 of fish oil (FO) (Diets F₂L₁, F₁L₂, and LO, respectively, or Diets F₂S₁, F₁S₂, and SO, respectively). A diet with FO alone was used as the control diet. LO or SO supplementation did not reduce the specific growth rate (3.06–3.29%/d) and feed efficiency ratio (0.75–0.83) of fish, but group F₂L₁ showed significantly better growth (P < 0.05) and feed utilization (P < 0.01) than group SO. Total replacement of FO with LO or SO significantly reduced certain non‐specific innate immune responses. Total replacement of FO by LO significantly increased the lipid content of fish. Concentrations of long‐chain polyunsaturated fatty acids (LC‐PUFAs) in whole fish and tissues were significantly reduced by LO or SO supplementation. In conclusion, LO or SO supplementations did not reduce the growth of Japanese seabass but reduced the immune responses and LC‐PUFA concentrations. LO was a better lipid source than SO for Japanese seabass in terms of fish growth and immune responses.     

Studies on the Growth of Common Carp, Cyprinus carpio L., in a Lake Fishery

Data are presented on the growth of an artificially stocked population of common carp, Cyprinus carpio L. in a South Lancashire rod and line lake fishery. The fish could not be aged from their scales and methods are described for the analysis of directly measured annual growth increments for tagged fish of unknown age in three size classes. Mean growth in weight for carp in the 454–2268 g (1–5 lb) and 2268–4536 g (5–10 lb) size classes was 0.23 and 0.19 kg year^?1; mean annual length increments were 10.8 and 4.4 mm, respectively. Carp >4536 g were observed to lose weight and length at a mean annual rate of 0.17 kg and 3.7 mm. The implication of these results to the stocking policy for the lake are discussed in conjunction with previously reported data on stock density and catchability. Comparisons between June/July length-weight regressions for carp at the time of tagging and after 1 and 2 years indicated no significant differences. Causes of growth inhibition by tagging reported by other authors are examined and considered to have been eliminated from the current study in which no adverse influence on growth could be detected. The effects of population density, competition with other species, chemical factors, weed growths and angling pressure on the growth rates of the carp are discussed and their implications to the management of the fishery considered.     

Turmeric Powder,Curcuma longa L., in Common Carp,Cyprinus carpio L., Diets: Growth Performance,Innate Immunity,and Challenge against Pathogenic Aeromonas hydrophila Infection

Microbial diseases cause economic loss in aquaculture on a global scale, and the use of commercial antibiotics for disease treatment produces undesirable side effects. As many medicinal herbs have evolved a potent defense against pathogenic bacteria, there is a growing interest in these herbs as sources for natural antibacterial agents. In this context, this study was undertaken to evaluate the effect of turmeric powder (TP), Curcuma longa, on the performance and innate immunity of common carp, Cyprinus carpio L., and its challenge against Aeromonas hydrophila infection. Fish (1.4 ± 0.06 g) were fed 0.0 (control), 1.0, 2.0, or 5.0 g TP/kg diet up to satiation twice daily for 10 wk. After the feeding trial, fish of each treatment were intraperitoneally injected by pathogenic A. hydrophila, and they were kept under observation for 10 d during which the daily mortality was recorded. The growth‐promoting effect of TP was monitored and observed where fish growth and innate immunity increased significantly as dietary TP levels increased. According to the regression curve, the most suitable TP level for optimal fish growth and health was found to be 2.0 g/kg. On the other hand, TP inclusion in the fish diet did not significantly affect fish body contents. The obtained results indicate that TP supplementation is a promising immunostimulant, which could improve fish performance and innate immunity and prevent common carp aermoniosis at a level of 2.0 g/kg diet.     

Effects of Different Dietary Lipid Sources on Growth Performance,Fatty Acid Composition,and Antioxidant Enzyme Activity of Juvenile Rockfish,Sebastes schlegeli

This study was carried out to investigate and compare the effects of various dietary lipid sources on growth performance, body composition, fatty acid profiles, and hepatic and plasma antioxidant enzyme activities of juvenile rockfish, Sebastes schlegeli. Three replicate groups of fish (initial mean weight, 1.7 ± 0.04 g) were fed four isonitrogenous and isolipidic diets containing either fish oil (FO), soybean oil (SO), linseed oil (LO), or a mixture of SO and LO (SO + LO) for 8 wk. There were no significant differences in survival, weight gain, feed efficiency, and protein efficiency ratios of fish fed the diets containing different lipid sources (P > 0.05). The fatty acids compositions of the liver and muscle tissues reflected the dietary fatty acid compositions. Liver and muscle of fish fed the SO diet had high concentration of linoleic acid, whereas those of fish fed the LO diet were rich in linolenic acid. Liver and muscle of fish fed the FO diet had significantly (P < 0.05) higher levels of eicosapentaenoic acid and docosahexaenoic acid than those of fish fed the SO and LO diets. Dietary lipid source had no significant effect on the hepatic and plasma enzyme activities of superoxide dismutase and glutathione peroxidase. The results of this study suggest that SO and LO can be used as a replacement for FO in the diets of juvenile rockfish without incurring any negative effects on growth, feed utilization, and antioxidant enzyme activity, when the dietary essential fatty acid requirements are satisfied for rockfish.     

Effects of Dietary Fish Oil Replacement with Palm Oil on the Growth,Feed Utilization,Biochemical Composition,and Antioxidant Status of Juvenile Chu's Croaker,Nibea coibor

A 56‐d feeding trial was conducted to evaluate the growth performance, feed utilization, biochemical composition, and antioxidant status of chu's croaker, Nibea coibor (12.6 ± 0.1 g) in net pens fed diets supplemented with various levels of crude palm oil: 0% fish oil (FO), 20% palm oil (2PO), 40% (4PO), 60% (6PO), 80% (8PO), and 100% (10PO). Weight gain and specific growth rate (SGR) were significantly lower in fish fed 8PO and 10PO diets. The increase of PO levels did not affect fish survival, feed intake, and feed conversion ratio. Feeding diet 10PO led to significantly higher lipid content in the liver, but not the whole body and dorsal muscle, than diets FO and 2PO. PO supplementation led to increased α‐tocopherol, but decreased thiobarbituric acid‐reactive substances, n‐3 highly unsaturated fatty acid (n‐3 HUFA), and n‐3/n‐6 fatty acid ratio, in both the liver and muscle. Hepatic superoxide dismutase and catalase were significantly higher in fish fed 10PO diet than FO diet. Polynomial regression analysis showed that the maximum SGR was obtained at 24.2% crude PO. Results of this study suggested that PO could replace up to 60% of FO without adverse effect on growth performance or nutritional quality of fish.     

Effects of Varying Dietary Fatty Acid Composition on Growth and Survival of Seahorse, Hippocampus Sp., Juveniles

Three commercially available fatty acid enrichment emulsions (DC Selco, DC DHA Selco and DC Super Selco) were used to enrich Artemia nauplii fed to seahorse, Hippocampus sp. fry. The emulsions varied in their n-3 highly unsaturated fatty acid (HUFA) composition. Total n-3 HUFA content ranged from 200 to 450mgg^-1 between the three emulsions while levels of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) ranged between 47–220 and 80–190mgg^-1, respectively. Survival and growth of seahorses at the end of the 30 day growth trial were greater in treatments receiving enriched Artemia. Seahorses receiving Artemia enriched with DC DHA Selco and DC Super Selco showed significantly (p < 0.05) greater mean survival (71.6 ± 6.0% and 78.3 ± 6.0%, respectively) than those receiving unenriched Artemia (48.3 ± 6.0%). Mean standard length was also significantly greater (p < 0.05) in fry fed DC DHA Selco and DC Super Selco enriched Artemia (20.2 ± 0.3 and 19.7 ± 0.3mm, respectively) compared to those fed unenriched Artemia (18.1 ± 0.3mm). The results show that dietary n-3 HUFA are essential for optimal growth and survival of Hippocampus sp. and, based on the fatty acid compositions of the enriched Artemia used in this study, indicate that the level of dietary DHA supporting optimal growth and survival is greater than 9.3mgDHAg^-1 dry weight.     

Effects of Dietary Gamma Aminobutyric Acid on Growth Performance,Antioxidant Status,and Feeding‐related Gene Expression of Juvenile Grass Carp,Ctenopharyngodon idellus

Gamma aminobutyric acid (GABA) is one of the inhibitory neurotransmitters that may have the ability to regulate the appetite. This study aimed to evaluate the effects of dietary GABA, as a feed additive, on growth performance and antioxidant status of juvenile grass carp. Five isonitrogenous and isoenergetic experimental diets with graded levels of GABA (0, 20, 50, 100 and 200 mg/kg) were fed to grass carp juveniles (mean weight: 2.0 g) for 8 wk. The results showed that the specific growth rate (SGR) increased significantly with dietary GABA level up to the 100 mg/kg diet, and then decreased in the 200 mg/kg group (P < 0.05). The difference in SGR value between the 50 and 100 mg/kg groups was not statistically significant (P > 0.05). The survival rate was not significantly affected by dietary GABA level (P > 0.05). No significant difference was observed in the whole body composition among treatments (P > 0.05). The hepatopancreatic glutathione peroxidase (GPx) activity increased significantly (P < 0.05) with the GABA level, peaked in the group with GABA 100 mg/kg, and then decreased. The hepatopancreatic superoxide dismutase and total antioxidant capacity activities showed the same trend as GPx. Inversely, the hepatopancreatic malondialdehyde content decreased first and then increased with the dietary GABA level (P < 0.05). No significant differences were observed in the gene expression of neuropeptide Y (NPY), cholecystokinin, leptin, and ghrelin in the hepatopancreas among groups. However, the NPY and ghrelin mRNA expression levels in the brain increased significantly with the GABA level, peaked in the groups of 50 mg/kg, and then showed a decreasing trend. On the basis of quadratic regression analysis of SGR, the optimum content of dietary GABA in juvenile grass carp is suggested to be a 87.5 mg/kg diet.     

Effect of Dietary Safflower and Canola Oil on Growth Performance,Body, and Fatty Acid Composition of Rainbow Trout (Oncorhynchus mykiss)

The objective of the present study was to evaluate the effects of the diets enriched with safflower and canola oil on growth, feed utilization, body composition, liver, and muscle fatty acid composition of rainbow trout (Oncorhynchus mykiss). Rainbow trout having approximate initial weight of 97.03 ± 0.10 g were fed the experimental diets containing only fish oil (Group 0SFO), safflower oil (50% safflower oil, Group 50SFO and 33% safflower oil, Group 33SFO), and vegetable oil blend (33% safflower and 33% canola oil, Group 66SFCO) for 45 days. Twenty-five fish were randomly assigned for triplicate treatments and offered the test diets two times daily to apparent satiation. At the end of the experiment, survival was 100% in all treatments. No significant differences in the weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio were found between fish fed with the different experimental diets. The highest hepatosomatic index (HIS) and viscerasomatic index (VSI) was obtained in 50SFO and 33SFO groups, respectively. The moisture, protein, lipid, and ash content in the body composition of the fish increased in all experimental groups. The lipid content was not significantly different among the groups (p > 0.05); however, there was a significant difference in ash content between the control and the other groups (p < 0.05). The experimental diets containing vegetable oil (50SFO and 33SFO groups) and vegetable oil blend (66SFCO group) had significantly higher concentrations of n-6 fatty acids, predominantly in the form of linoleic acid (LA). The n-3 fatty acids were present in significantly higher concentration in the control treatment (0SFO). The fatty acid composition of fish fillet and liver were reflective of the dietary lipid source. While the fillet and liver of fish fed the 50SFO diet was high in linoleic acid (18:2 n-6), fish fed the 66SFCO diet had high concentrations of oleic acid (OA; 18:1 n-9). The present study suggests that fish oil can be replaced by up to 50% with safflower oil and by up to 66% with safflower + canola oil blend in rainbow trout diets with no significant effect on growth.     

微粒饲料中以微藻粉替代鱼油对牙鲆(Paralichthys olivaceus)稚鱼生长存活和脂肪酸组成的影响

以18日龄的牙鲆(Paralichthys olivaceus)稚鱼为研究对象,通过11 d 的生长实验,研究了添加不同比例的微藻粉替代鱼油对牙鲆稚鱼生长、存活率和脂肪酸组成的影响。以鱼油组(FO)为对照组,以裂壶藻粉(Schizochytrium sp.)、微绿球藻粉(Nannochloropsis sp.)和橄榄油替代不同比例的鱼油,配制成5组等氮等能的实验饲料,分别命名为鱼油组(FO),50%混合替代组(M50)、100%混合替代组(M100)、100%裂壶藻橄榄油替代组(S100)、100%微绿球藻橄榄油替代组(N100)。结果显示,微藻粉替代鱼油对牙鲆稚鱼的生长无显著影响;含有裂壶藻的各饲料组(M50、M100、S100)成活率显著高于 FO 组和 N100组(P?0.05);微藻粉替代鱼油不影响牙鲆稚鱼主要脂肪酸的组成;Person相关性分析发现,C14：0、C16：1n-7、C18：2n-6、C20：0、C18：3n-3、C22：0、C20：4n-3、EPA、C22：5n-6和 DHA 的百分含量均与其饲料中的百分含量呈显著正相关(P<0.05);总饱和脂肪酸、总单不饱和脂肪酸、n-3多不饱和脂肪酸的百分含量以及 DHA/EPA 比率均与其饲料组成表现出显著正相关(P<0.05)。综上所述,微藻作为脂肪源替代鱼油完全可以满足牙鲆稚鱼的生长和发育,各种脂肪酸均可以被牙鲆稚鱼充分消化和吸收,并且添加两种微藻后提高了稚鱼的 DHA 含量和 DHA/EPA 比率,与鱼油对照组相比显著提高了牙鲆稚鱼的成活率。因此,以微藻替代鱼油在牙鲆稚鱼的培育中是可行的。     

豆油和菜油对鲫鱼生长、体成分及血清生化指标的影响

分别以豆油、菜油、混合油(豆油:菜油=1:1)作为脂肪源,制成3种试验饲料,饲养体重为(27.64±2.29)g的鲫57 d,对试验鱼生长、生物学性状、体成分、血清生化指标进行测定,以综合评价豆油和菜油对鲫(Carassius auratus)的影响并进行比较.结果表明,菜油组和豆油组终末体重差异不显著,但均显著高于混合油组(P<0.05);饲料系数、增重率、绝对生长率各组间均无显著差异;内脏指数菜油组和豆油组差异不显著,但均高于混合油组(P<0.05);菜油组的含肉率显著低于混合油组(P<0.05),两者与豆油组差异不显著;菜油组的肝体比显著高于混合油组(P<0.05),两者与豆油组差异不显著;菜油组的肠体比和豆油组差异不显著,但均高于混合油组(P<0.05);肠长比各组间差异均不显著;菜油组的肥满度最高,混合油组最低,且组间差异显著(P<0.05);豆油组肌肉粗蛋白含量显著高于菜油组(P<0.05),与混合油组间差异不显著;混合油组肌肉粗灰分含量显著高于菜油组(P<0.05),与豆油组含差异显著;鱼体肌肉水分、粗脂肪、肝胰脏脂肪含量及血清生化指标各组间差异不显著.研究结果显示,豆油、菜油单独作为脂肪源对鲫生长、血清牛化性状的影响没有显著差异,但豆油能够改善鲫的体形,提高鲫的肌肉粗蛋白含量,而2种油脂混合使用则抑制鲫的生长,其原因可能与鲫的消化道发育受到抑制有关.建议生产中使用豆油为鲫的脂肪源,并避免同时使用豆油和菜油.     

蚕粉替代鱼粉对加州鲈幼鱼生长、饲料利用及体成分的影响

本研究评价了蚕粉对加州鲈(Micropterus salmonides)幼鱼生长、饲料利用率和体成分的影响。选用初始均体重为(3.13±0.04) g的加州鲈540尾,随机分成6个实验组,每组3个重复,每个重复30尾实验鱼,分别以蚕粉替代0(对照组)、10%、20%、30%、40%和50%的鱼粉设计出6种等氮、等能的饲料配方,按照配方配制实验饲料。由于后期养殖气温下降,不适合继续进行实验,本养殖时间为45 d。结果显示,加州鲈的增重率(WGR)、特定生长率(SGR)及蛋白质效率(PER)均随蚕粉替代水平的升高呈先上升后下降的变化趋势,且其WGR、SGR和PER均在蚕粉替代水平为30%时达到最大(分别为227.87%、1.98%/d和164.55%)(P0.05);饲料系数(FCR)则随蚕粉替代水平的升高呈先降后升的变化趋势,且在蚕粉替代水平为30%时达到最低(为1.43)(P0.05);肥满度(CF)、肝体比(HSI)、脏体比(VSI)则随蚕粉替代水平的升高而呈先上升后下降并趋于稳定的趋势(P0.05);实验期间各组实验鱼的成活率(SR)差异不显著(P0.05)。通过二次回归分析可知,加州鲈幼鱼WGR、SGR、FCR及PER最优时饲料的蚕粉替代比例分别为19.90%、22.00%、18.11%和17.90%;加州鲈全鱼粗脂肪含量随蚕粉替代水平的升高呈先降低后升高的变化趋势(P0.05),粗蛋白含量随蚕粉替代水平的升高无明显变化(P0.05),水分除蚕粉替代水平为10%和40%组差异显著外(P0.05),其余各实验组差异不显著(P0.05),蚕粉替代水平大于20%时,全鱼灰分显著降低(P0.05)。在本实验条件下,综合考虑实验鱼的生长指标、饲料利用和体成分,饲料中蚕粉适宜的替代水平为17.90%～22.00%。     

Effects of Dietary DHA/EPA Ratios on Fatty Acid Composition,Lipid Metabolism‐related Enzyme Activity,and Gene Expression of Juvenile Grass Carp,Ctenopharyngodon idellus

To determine the effects of docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratios on grass carp, Ctenopharyngodon idellus, a 38‐d feeding trial was conducted using six isonitrogenous and isoenergetic semi‐purified diets containing constant n‐3 long‐chain polyunsaturated fatty acid (LC‐PUFA) (0.5% of dry matter), but varying ratios of DHA to EPA and a control diet (no n‐3 LC‐PUFA was included). The results revealed higher final weight and specific growth rate in the DHA/EPA 0.21 group. The n‐3 LC‐PUFA content increased in the CK (control) groups compared with that in the control diet. Lipoprotein lipase (LPL) activity increased in the treatment groups. Malate dehydrogenase showed lower activity in the DHA/EPA 1.08 group, as well as to the change in the level of glucose‐6‐phosphate dehydrogenase (G6PDH). The gene expressions of LPL increased in the treatment groups and that of peroxisome proliferator‐activated receptor α gene showed higher expressions in DHA/EPA 1.08, 0.49, and 0.21 groups. However, no remarkable differences were found among the six groups in the peroxisome proliferator‐activated receptor γ gene expression. Our findings indicated that dietary n‐3 LC‐PUFA affected fatty acid composition and lipid metabolism of grass carp. Further, fish achieved the best effect in decreasing the lipid accumulation when dietary DHA/EPA ratio was not greater than 1.     

拟微绿球藻粉替代鱼粉对大菱鲆幼鱼生长性能、体组成和血清生化指标的影响

为探讨拟微绿球藻(Nannochloropsis sp.)粉替代鱼粉对大菱鲆(Scophthalmus maximusL.)幼鱼生长性能、体组成和血清生化指标的影响,用拟微绿球藻粉替代基础饲料中0%、3.88%、7.76%、11.64%和15.52%的鱼粉,配制成5种等氮等能的饲料(N_0、N_(3.88)、N_(7.76)、N_(11.64)、N_(15.52))。选取初始体重为(24.60±0.02) g的大菱鲆幼鱼600尾,随机分成5组,每组3个重复,每个重复40尾鱼,养殖周期70d。结果显示:1)各实验组大菱鲆幼鱼的增重率(WGR)、特定生长率(SGR)、蛋白质效率(PER)、饲料系数(FCR)、日摄食率(DFI)、肥满度(CF)和成活率(SR)均无显著差异(P0.05);2)随着藻粉添加量的增加,全鱼及肌肉中粗脂肪含量显著降低(P0.05),粗蛋白、粗灰分和水分含量无显著差异(P0.05);3)血清溶菌酶(LZM)、补体蛋白C3、补体蛋白C4及酸性磷酸酶(ACP)活力均呈先上升后下降的趋势,分别在N_(7.76)、N_(7.76)、N_(11.64)、N_(7.76)组达到最大值,且显著高于N_0组(P0.05),N_(15.52)组碱性磷酸酶(ALP)显著低于其他组(P0.05),其他组之间无显著差异(P0.05);4)藻粉组血清总超氧化物歧化酶(T-SOD)、总抗氧化能力(T-AOC)和谷胱甘肽过氧化物酶(GSH-PX)活力,均呈先上升后下降的趋势,在N_(7.76)组达到最大值,且显著高于N_0组(P0.05);5) N_(7.76)组血清甘油三酯(TG)含量显著低于其他组(P0.05),其他组之间无显著差异(P0.05),藻粉组血清总胆固醇(TCHO)显著低于N0组(P0.05),各藻粉组之间差异不显著(P0.05);6)藻粉组血清谷草转氨酶(AST)活力呈先下降后上升的趋势,N_(11.64)组达到最小值,显著低于N_0组(P0.05),藻粉组谷丙转氨酶(ALT)活力显著低于N_0组(P0.05)。研究表明,本实验条件下,拟微绿球藻粉替代大菱鲆幼鱼饲料中15.52%的鱼粉对其生长无显著影响,替代7.76%可显著提高其非特异性免疫力,降低血脂水平。     

Growth Performance,Fatty Acid Composition,Peroxisome Proliferator‐activated Receptors Gene Expressions,and Antioxidant Abilities of Blunt Snout Bream,Megalobrama amblycephala,Fingerlings Fed Different Dietary Oil Sources

A 60‐d feeding trial was conducted to evaluate the effects of different dietary oil sources on growth, fatty acid composition, peroxisome proliferator‐activated receptor (PPAR) gene expression levels, and antioxidant responses of blunt snout bream, Megalobrama amblycephala, fingerlings. Fish (average initial weight, 0.35 ± 0.01 g) were fed five experimental diets respectively containing fish oil (FO), soybean oil, canola oil, peanut oil, and palm oil (PaO). Results showed that body weight gain, specific growth rate, and feed conversion ratio did not significantly differ among treatments. Fish fed PaO diet showed significantly higher hepatosomatic index value and liver lipid content than those fed FO diet. The FO group showed significantly higher liver eicosapentaenoic acid (20:5n‐3) + docosahexaenoic acid (22:6n‐3) concentrations than other groups in both neutral lipid and polar lipid fractions. The mRNA expression levels of PPAR‐α and PPAR‐γ in the liver were significantly increased by feeding vegetable oil diets compared to FO. The activities of catalase, superoxide dismutase, and glutathione peroxidase in livers of fish fed PaO diet were lower than those fed FO diet. Meanwhile, PaO group had significantly lower malondialdehyde value than other groups. In conclusion, we suggested that a combination of FO and vegetable oil diet should be used in feed formulations for blunt snout bream fingerlings.     

Effect of Dietary n‐3 highly unsaturated fatty acids on Growth,Body Composition and Fatty Acid Profiles of Juvenile Black Seabream,Acanthopagrus schlegeli (Bleeker)

An 8‐wk feeding trial was conducted to investigate the effects of dietary n‐3 highly unsaturated fatty acids (n‐3 HUFA) on growth, body composition, and fatty acid profiles of juvenile Acanthopagrus schlegeli. Three replicate groups of fish (initial mean weight: 8.08 ± 0.09 g, mean ± SD) were fed diets with different levels of n‐3 HUFA (0.76%, HUFA_0.76; 0.83%, HUFA_0.83; 0.90%, HUFA_0.90; 0.97%, HUFA_0.97; 1.04%, HUFA_1.04; 1.12%, HUFA_1.12) at 12.9% of total lipid, with a constant eicosapentaenoic acid (EPA, 20:5n‐3) to docosahexaenoic acid (DHA, 22:6n‐3) ratio of about 2.1. Hepatosomatic index (HSI) and intraperitoneal fat (IPF) ratio were all linearly depressed by dietary n‐3 HUFA levels (P < 0.05), and condition factor (CF) was not affected. Adipocyte diameter in IPF decreased with the elevation of dietary n‐3 HUFA and significance occurred between group HUFA_0.90 and HUFA_1.12. Lipid content in dorsal muscle was significantly lowered by dietary n‐3 HUFA compared to fish fed diet HUFA_0.76. No significance was found in whole fish proximate composition. In liver, dorsal muscle and IPF, ∑SFA, 16:0 or ∑n‐3 HUFA were all positively correlated with dietary n‐3 HUFA, while DHA to EPA ratios remained constant in 2.68, 2.86, and 3.60, respectively. Fatty acid synthase (FAS, EC 2.3.1.85) activities of all treatments remained constant at first and then were significantly elevated by dietary n‐3 HUFA higher than 0.97% (P < 0.05). In contrast, hormone sensitive lipase (HSL, EC 3.1.1.3) changed following an opposite tendency. Quadratic analysis based on weight gain rate (WGR) indicated that dietary n‐3 HUFA requirement for juvenile black seabream was 0.94% of the diet in 12.9% lipid diets .     

Growth,Survival, and Whole‐body Proximate and Fatty Acid Composition of Haddock,Melanogrammus aeglefinus L., Postlarvae Fed a Practical Microparticulate Weaning Diet

Further development of high‐quality feeds for hatchery‐reared haddock in the North Atlantic would benefit from a standard formulation that can be used as a reference for hatcheries and laboratory studies. A practical microparticulate diet (PMD) developed and evaluated with newly metamorphosed juvenile haddock, Melanogrammus aeglefinus L., postlarvae is proposed. Survival of fish fed PMD was just as high (88–89%; P > 0.05) as those fed a high‐quality imported feed (Biokyowa). Alternatively, fish fed PMD had higher (P < 0.05) final fork lengths (39.5 vs. 35.1 mm), wet weights (851.3 vs. 580.2 mg) and weight gains (1637.2 vs. 1115.7%). No differences (P > 0.05) in whole‐body moisture (846–857 g/kg), ash (17–18 g/kg), or protein (101 g/kg) contents were found. Lipid content of fish fed PMD (26 g/kg) was higher (P < 0.05) than those fed Biokyowa (21 g/kg) despite PMD containing 15 g/kg lower dietary lipid, suggesting higher intake and/or lipid retention. The PMD formulation proved to be a highly suitable weaning diet for haddock postlarvae based on high feed acceptance, survival, and fish growth. Given the economic and logistical difficulties associated with importing commercial weaning feeds, this easily produced practical weaning diet has good potential for use by laboratory researchers and farm managers for hatchery‐based nutrition research with haddock postlarvae.     

Interactive Effects of Vitamin C and E Supplementation on Growth,Fatty Acid Composition,and Lipid Peroxidation of Sea Cucumber,Apostichopus japonicus,Fed with Dietary Oxidized Fish Oil

A feeding trial was conducted to determine the interactive effects of vitamin C (ascorbic acid, AsA) and E (α‐tocopherol, α‐Toc) supplementation with dietary oxidized fish oil (OFO) on the growth performance, whole‐body AsA, and α‐Toc concentrations and fatty acid composition of juvenile sea cucumber. In a 9‐wk feeding trial, juveniles (average weight: 0.6 ± 0.1 g) were cultured in twenty‐four 50‐L tanks (30 juveniles per tank) in triplicate, and fed with eight test diets containing two levels of OFO (8.9 and 156.9 meq/kg) with varying levels of vitamin C (500 and 1000 mg AsA equivalents/kg diet) and E (100 and 200 mg α‐Toc equivalents/kg diet) supplementation, respectively. Body weight gain of sea cucumber was significantly reduced by dietary OFO, while mortality and whole‐body thiobarbituric acid‐reactive substances value were increased significantly. Increasing dietary vitamin C and E levels significantly increased whole‐body α‐Toc and AsA concentrations, respectively. A high level of vitamin E combined with OFO led to consumption of AsA. Even with supplementation of a large dose of vitamin C and/or E in diets, growth performance could not be improved, probably due to the high levels of vitamins in the control diets.     

Effect of Dietary Gamma‐irradiated and Fermented Soybean Meal on the Growth Performance,Body Composition,and Digestive Enzymes Activity of Caspian Brown Trout,Salmo trutta caspius,Juvenile

This experiment was conducted to evaluate the feasibility of gamma‐irradiated soybean meal (SBM) as a dietary ingredient on the performance, body composition, and digestive enzyme activity of Caspian brown trout, Salmo trutta caspius, juveniles. Five isonitrogenous and isoenergetic diets were formulated, in which fish meal was replaced by untreated (untreated SBM), gamma‐ray irradiated at 15 (15ISBM) and 30 (30ISBM) kGy, fermented (FSBM), fermented 15 KGy irradiated soybean meal (FISBM), respectively. Juvenile fish (2.1 ± 0.3 g) were fed with the test diets for 6 wk. Final body weight was significantly affected by dietary SBM treatment with highest values in fish fed FISBM and FSBM (P < 0.05). There were no significant differences in hepatosomatic and visceral indexes, condition factor, and survival among experimental groups (P > 0.05). The carcass proximate composition of lipid and protein in Caspian brown trout in FSBM and FISBM groups was higher than that of other groups. Levels of most whole‐body amino acids were not significantly different among Caspian brown trout fed the five diets. Results of this experiment showed that replacing SBM with FSBM and FISBM in the diet significantly increased the activities of proteolytic enzymes activities (P < 0.05). However, no significant differences were observed in both amylase and lipase activities among dietary treatments. Results of this study indicated that the level of gamma radiation used did not work but fermentation of SBM did increase some growth parameters of Caspian brown trout.     

Influence of replacing fish meal with enzymatic hydrolysates of defatted silkworm pupa (Bombyx mori L.) on growth performance,body composition and non‐specific immunity of juvenile mirror carp (Cyprinus carpio var. specularis)

This study was conducted to investigate the effects of dietary supplementation of enzymatic hydrolysates of defatted silkworm pupa (EHDSP) on growth performance, body composition and non‐specific immunity of juvenile mirror carp (Cyprinus carpio var. specularis). The control diet (EHDSP0) was produced using fish meal (FM) as the main protein source and the other four diets were formulated by substitution of 25% (EHDSP25), 50% (EHDSP50), 75% (EHDSP75) and 100% (EHDSP100) FM with EHDSP. Five groups containing 270 juvenile mirror carp (14.51 ± 0.03 g) were fed to apparent satiation for 8 weeks. The results indicated that the special growth rate, weight gain, protein efficiency ratio and feed conversion rate of experimental fish in EHDSP25 and EHDSP50 groups were not significantly different from EHDSP0 group (p > .05). The spleen index of experimental fish in EHDSP25 group was significantly higher than that of EHDSP0 group (p < .05). The muscle protein content of experimental fish in EHDSP25 and EHDSP50 groups was significantly higher than that of EHDSP0 group (p < .05). Serum alanine aminotransferase and total cholesterol of experimental fish fed with the EHDSP were significantly lower than that of control (p < .05). The activity of serum superoxide dismutase of experimental fish in EHDSP25, EHDSP50 groups was significantly higher than that of EHDSP0 group (p < .05). Intestinal trypsin activity of EHDSP25 group was significantly higher than that of EHDSP0 (p < .05). In conclusion, EHDSP can be included into diet to replace 50% FM of juvenile mirror carp without negative effect on growth, furthermore, it can improve the non‐specific immunity and function of intestinal tract.