Dietary protein/lipid level and protein source effects on growth,tissue composition and lipid metabolism of blackspot seabream (Pagellus bogaraveo)

A study was carried out to determine the effects of fish meal (FM) replacement by plant protein (PP) on growth, body composition and lipid metabolism of blackspot seabream fed different protein/lipid levels. Four experimental diets were formulated to contain two protein (P) and lipid (L) levels (60P/6L or 50P/10L), varying in their protein source (100% FM or 50% FM: 50% PP). Dietary inclusion of PP did not affect growth of fish fed 60P/6L, although fish fed 50P/10L exhibited lower final body weight and daily growth index. Fish fed 60P/6L presented the highest protein and the lowest lipid content. FM replacement by PP has decreased muscle n‐3 whereas the n‐6 fatty acids increased. Glucose‐6‐phosphate dehydrogenase and fatty acid synthetase (FAS) were depressed in fish fed 50P/10L. FAS was significantly increased with 60P/6L PP which was positively correlated with lipid retention data. Those results suggest the conversion of other nutrient than lipid (protein and/or carbohydrates) into corporal fat. Hepatic lipoprotein lipase activity was lowest in fish fed PP diets. Plasma glucose peaked 1–2 h postfeeding, in all groups and was generally higher with 60P/6L FM. This work shown that besides dietary P/L level, protein source has a strong effect on species lipogenesis and lipid retention. Hence, the 50P/10L FM diet was the most cost‐effective for blackspot seabream juveniles.     

Measuring technical,allocative and cost efficiencies of seabass and seabream farms in Greece

Abstract

A stochastic Cobb‐Douglas production frontier is used to provide estimates of output‐oriented technical efficiency, input‐oriented technical efficiency, input allocative efficiency and cost efficiency for a sample of seabass and seabream farms in Greece. Mean output‐oriented technical efficiency is estimated at 78.5%, input‐oriented technical efficiency at 73.6%, input allocative efficiency at 79.2%, and cost efficiency at 58.2%. Considering the sources of efficiency differentials among fish farms, it is evidence from the empirical results that large farms tend to achieve higher (technical and allocative) efficiency scores; specialization in either seabass or seabream affects positively technical and cost, but not allocative, efficiency; and utilization of skilled labor seems to have a positive impact only on technical efficiency.     

Visualization analysis of seabream and seabass aquaculture research using CiteSpace

In terms of production, seabream and seabass are the two most important species of marine Mediterranean aquaculture, which is why they have been extensively studied in the literature. This study uses visualization analysis with the CiteSpace software to determine the research status quo and the most important trends of seabream and seabass aquaculture research. The Web of Science (WoS) database was used to select the papers associated with seabream and seabass literature from the period between 1986 and 2020. The results were separated using two indices (Science Citation Index Expand and Social Science Citation Index). The visualization analysis identified the networks for (1) author, institution, country and category co-authorship, in order to find the most prolific authors, institutions, countries and categories respectively; and (2) journal, document and author co-citation, which identifies the most relevant journals, the most important studies and the most cited and influential authors. Finally, a keywords co-occurrence network was built to identify the most important topics and the research frontiers—body of knowledge—of the seabream and seabass aquaculture research—SSAR.     

Dietary krill meal inclusion contributes to better growth performance of gilthead seabream juveniles

There is a need to find sustainable alternatives to fishmeal (FM) and fish oil (FO) in feed formulations to support the continued growth of aquaculture. FM is mostly produced from mass‐caught pelagic species, but the production has been relatively constant for several decades. The aim of this study was to investigate the potential of dietary krill meal (KM) inclusion as a sustainable alternative to FM. In view of that, a feeding trial with gilthead seabream juveniles was conducted to evaluate whether dietary KM at 3%, 6% and 9% inclusion improves growth performance in comparison with a control diet. At the end of the study, fish in the 9% KM group showed significantly higher body weight (32.76 g) compared with fish fed the control diet (30.30 g). Moreover, FM replacement by 9% KM indicated a reduction in the accumulation of lipid droplets in the hepatocytes and around the pancreatic islets. In summary, this study suggests that FM can be reduced in diets for seabream without negatively affecting growth performance, when KM is added. On the contrary, KM enhances gilthead seabream growth and reduces lipid accumulation and damage of hepatocytes, which will open an interesting innovation line to completely replace FM by alternative terrestrial protein sources and the partial inclusion of KM.     

Effects of different dietary lipid sources on growth performance,body composition and lipid metabolism‐related enzymes and genes of juvenile golden pompano,Trachinotus ovatus

Three groups of juvenile golden pompano, Trachinotus ovatus (54.75 ± 0.25 g), were each fed one of three diets containing different lipid sources: fish oil (FO), soybean oil (SO) and lard oil (LO). Fish were reared in sea cages for 8 weeks, and the fish fed the FO diet had significantly higher specific growth rate (SGR) but lower condition factor (CF) than the other treatments. The fatty acid (FA) composition of whole‐body lipids was closely correlated with those in the diets. Although no differences can be found in hepatic fatty acid synthase (fasn) activity, the carnitine palmitoyl transferase 1 (cpt1) activity in fish fed the FO diet was significantly higher compared with other treatments. In addition, the relative gene expression of lipid metabolism‐related enzymes, such as cpt1, fas, apolipoprotein B100 (apoB100), delta‐6 fatty acyl desaturase (fadsd6) and fatty acid‐binding protein 1 (fabp1), was also influenced by the different dietary lipid sources. Serum triglyceride (TG) and glucose content in fish fed the LO and FO diets were significantly higher than those in the SO group. Accordingly, it can be concluded that FO could not be completely replaced by SO or LO in golden pompano diets. The lipid sources of a diet could impose significant influence on body condition factor and hepatic lipid metabolism of golden pompano.     

不同脂肪源日粮补充维生素E对罗氏沼虾生长、免疫及肉品质的影响

本研究旨在完善罗氏沼虾（）饲料配方,降低罗氏沼虾饲料成本。研究采用3×2双因素设计,配制6组饲料,分别包含鱼油（fish oil,FO）、豆油（soybean oil,SO）、菜籽油（rapeseed oil,RO）三种脂肪源;200 mg/kg（200VE）和600 mg/kg（600VE）两个维生素E（VE）水平。养殖实验在温室水泥池中进行,每个处理3个重复,养殖期8周,每天定点定量投喂3次。结果显示,相对于FO组,SO和RO组增重率、特定生长率显著升高,饵料系数显著下降（>0.05）。对于血淋巴抗氧化指标,在相同VE水平下,FO组血淋巴总抗氧化能力（T-AOC）和超氧化物歧化酶（SOD）活性均显著低于SO和RO组,谷胱甘肽过氧化物酶（GPX）活性均显著高于SO和RO组（<0.05）。在相同脂肪源下,600VE可显著提高FO组T-AOC活性,RO组GPX活性以及SO和RO组SOD活性（>0.05）。对于血淋巴生理生化指标,谷草转氨酶（AST）、总蛋白（TP）、白蛋白（ALB）和甘油三酯（TC）受日粮影响显著（<0.05）。此外,日粮脂肪源和VE水平对肉质也有显著影响。其中,SO组肌肉鲜度和滋味强度较高;RO组鱼腥味较低;FO组肌肉亮度较高,气味强度较低。在200 mg/kg VE水平下,FO组肌肉硬度、胶黏性、耐咀性、黏性和回复性显著高于植物油组（<0.05）,而对肌肉蒸煮损失和滴水损失无显著影响（>0.05）。上述结果表明,相对于鱼油,豆油和菜籽油等植物油是罗氏沼虾更优质的脂肪源,VE在以鱼油为单一脂肪源的饲料中有一定的促生长和缓解应激的作用,且脂肪源和VE均显著影响肌肉品质。本研究结果将为降低鱼油在罗氏沼虾饲料中的使用提供数据支持。     

Alternative vegetable lipid sources in diets for grouper, Epinephelus coioides (Hamilton): effects on growth, and muscle and liver fatty acid composition

The aim of this study was to investigate the effects of different oils on growth performance and lipid metabolism of the grouper, Epinephelus coioides. Five experimental fish meal‐based isonitrogenous and isolipidic diets were formulated containing either 5.5%‐added fish oil (FO), soybean oil (SBO), corn oil (CO), sunflower oil (SFO) or peanut oil (PO). Each diet was fed to triplicate groups of 20 fish (initial body weight 13.2±0.02 g) grown in seawater at 28.0–30.5 °C for 8 weeks. Fish were fed twice a day to visual satiety. No significant differences in the survival, weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio or hepatosomatic index were found between fish fed the FO or vegetable oils (VO) diets. Dietary lipid sources did not affect whole‐body composition among grouper fed the various diets. Muscle of fish fed the FO diet had significantly higher levels of 14:0, 16:0, 16:1n‐7, 20:5n‐3[eicosapentaenoic acid (EPA)] and docosahexaenoic acid (DHA)+EPA (except for PO fed fish) compared with those of fish fed VO diets. However, the levels of 18:1n‐9, 18:2n‐6 and DHA/EPA ratios in the muscle of fish fed FO diet were significantly lower than those of fish fed the VO diets. The liver of fish fed the FO diet had significantly higher levels of 18:0, 20:5n‐3, 22:6n‐3, n‐3 highly unsaturated fatty acids and DHA+EPA than those of fish fed the VO diets, whereas increases in 18:1n‐9, 18:2n‐6 and mono‐unsaturated fatty acid levels were observed in the liver of fish fed the VO diets.     

Effects of dietary lipid sources on growth performance,lipid metabolism and antioxidant status of juvenile Russian sturgeon Acipenser gueldenstaedtii

Six isonitrogenous and isoenergetic diets were used to test the influence of lipid source on growth performance, antioxidant status and lipid metabolism of juvenile Russian sturgeon, Acipenser gueldenstaedtii. Each diet was supplemented with 90 g kg^?1 of lipid from each of six sources including fish oil (FO), beef tallow (BT), sunflower oil (SO), linseed oil (LO) and equal combinations of FO + SO + BT (FSB) or LO + SO + BT (LSB). After 56 days, fish fed LSB demonstrated highest weight gain, specific growth rate and lowest hepatosomatic index among all groups. The n‐6 polyunsaturated fatty acids (PUFAs) in the whole fish were highest in the SO group, and n‐3 PUFAs were highest in fish fed LO. The fish fed FO contained highest n‐3 highly unsaturated fatty acids. Triglyceride in the serum of fish fed LSB was lowest, but was not significantly different from that in the SO group. Triglyceride in the serum of fish fed FO and BT was highest among all groups. Lipase, malate dehydrogenase and lipoprotein lipase activities were highest in fish fed LSB. Serum malondialdehyde in fish fed LSB was significantly lower than in fish fed FO or SO, but no significant differences were found among fish fed LSB, BT, LO or FSB. Fish fed LSB showed higher catalase activity and total antioxidant capacity than fish fed FO or FSB. This study indicates that linseed, sunflower oil and BT mixed oil are a suitable lipid source and can benefit growth performance and antioxidation in juvenile sturgeon.     

饲料中碳水化合物水平对鲈鱼生长、生理状态参数及体组成的影响

以初始体重(34.26±0.37)g的鲈鱼Lateolabrax japonicus为研究对象,进行为期70d的生长实验,探讨饲料中不同的碳水化合物(CHO)水平对其生长、饲料利用、血糖水平和糖酵解酶活力的影响。实验配制6种不同CHO水平(0、6%、12%、18%、24%和30%)的等氮等脂饲料。结果表明,随着饲料中CHO水平的升高,特定生长率(SGR)和饲料效率(FE)均呈现先上升后下降的趋势,都在12%组达到最大值,并显著高于24%和30%组(P0.05),而肝体比(HSI)和脏体比(VSI)呈显著升高的趋势(P0.05),且在30%组达到最大值。饲料中不同CHO水平对鲈鱼成活率、肥满度、肌糖原和己糖激酶(HK)活力均无显著影响(P0.05)。饲料中不同CHO水平显著提高了鲈鱼粗蛋白和粗脂肪含量(P0.05),降低了灰分含量(P0.05)。饲料干物质的表观消化率(ADC)在各组之间差异显著(P0.05),18%组显著高于其余5组(P0.05),12%组饲料蛋白质的ADC显著高于对照组(P0.05)。血清中葡萄糖、甘油三酯、胆固醇含量随着饲料中CHO水平的增加而逐渐上升(P0.05),肝糖原含量先显著升高后趋于平稳(P0.05)。以SGR为评价指标,用二次曲线模型分析得出鲈鱼饲料中CHO的适宜添加量为17.75%。     

Evaluation of carbohydrate‐to‐lipid ratio in diets supplemented with Bacillus subtilis probiotic strain on growth performance,body composition and digestibility in juvenile white seabass (Atractoscion nobilis,Ayres 1860)

This study aimed to evaluate the effect of increasing the carbohydrate to lipid ratio in diets supplemented with Bacillus subtilis in white seabass (Atractoscion nobilis) juveniles on digestibility, growth performance, feed utilization efficiency and tissue composition. Four experimental isoenergetic and isoproteic diets supplemented with B. subtilis were formulated with increasing starch to lipid ratios (g/g) of 10:19; 14:17; 18:15 and 22:13 (diets PD10, PD14, PD18 and PD22 respectively). A negative control diet for B. subtilis supplementation was also formulated to be similar to diet PD10 (diet CD10). Each experimental diet was fed to triplicate groups of 20 fish per tank (IBW: 9.5 g), three times a day, to apparent satiation, for 60 days. Supplementation with B. subtilis, of the low starch‐high lipid diet (10:19), significantly enhanced the overall growth performance, digestibility and feed efficiency. Moreover, the increase in starch to lipid ratio, in supplemented probiotic diets, significantly increased growth performance, feed intake, feed utilization efficiency and protein and energy digestibility, being maximum for the highest dietary starch to lipid level. Lipid content of whole body, muscle and liver and hepatosomatic index significantly increased with the increase in starch to lipid ratio. The results of this study indicate that B. subtilis supplementation significantly enhanced growth performance, digestibility and feed utilization of low starch‐high lipid diet. However, further improvement of growth performance and feed utilization efficiency may be achieved combining B. subtilis supplementation with increased dietary starch to lipid ratio to 22:13.     

饲料中添加氧化鱼油对黑鲷幼鱼生长的影响

研究了饲料中添加氧化鱼油对黑鲷（Acanthopagrus schlegeli）生长性能、脂质过氧化及肝组织结构的影响。分别以新鲜鱼油（过氧化物值POV，1．27meq O2·kg^-1油）与氧化酸败鱼油（POV，45meq O2·kg^-油）为脂肪源配制等蛋等能的两种配合饲料，投喂平均体重18．9g的黑鲷幼鱼9周。结果显示，氧化鱼油显著降低了黑鲷幼鱼的增重率（WG）、饲料效率（FE）及蛋白质效率（PER）（P〈0．05）。饲料中添加氧化鱼油导致鱼体蛋白质含量极显著降低（P〈0．01）、肝脏与肌肉中脂肪含量显著升高（P〈0．05），而对鱼体、肝脏及肌肉中的水分及灰分含量无显著影响（P〉0．05）。氧化鱼油组肝脏中脂质过氧化产物丙二醛（MDA）含量显著高于对照组，而维生素E含量则显著低于对照组（P〈0．05）。饲料中添加氧化鱼油显著影响黑鲷肝脏内主要抗氧化酶活性，氧化鱼油组肝脏中超氧化物歧化酶（SOD）与过氧化氢酶（CAT）活性显著高于对照组（P〈0．05）；组织学结果显示氧化鱼油组肝脏出现明显病变，细胞核多集中在肝细胞边缘，肝细胞变大。统计分析表明，氧化酸败油脂显著降低了黑鲷的生长性能，加重了组织中脂质过氧化的程度，并导致肝脏组织发生病变。     

Influence of n-3 highly unsaturated fatty acid deficiency on the lipid composition of broodstock gilthead seabream (Sparus aurata L.) and on egg quality

A feeding experiment was conducted on gilthead seabream (Sparus aurata) broodstock to investigate the incidence of n-3 highly unsaturated fatty acids (n-3 HUFA) dietary deficiencies on the lipid composition of female liver, gonads and eggs, in relation to spawning quality. Broodstock were fed a control (C) diet or a n-3 HUFA deficient (D) but linolenic acid rich diet. After 20 weeks of feeding, the results showed that levels of total neutral (TNL) and total polar (TPL) lipids of female gonads and eggs were independent of diet. However the fatty acid composition of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) of female liver, gonads and eggs in the two groups of fish showed marked differences, reflecting the influence of fatty acid levels in the broodstock diets. This influence was even higher in TNL than in the phospholipid classes examined. In fish fed n-3 HUFA deficient diet, fatty acid composition of TNL of female gonads and eggs reflected the diet more than liver. A higher egg production in broodstock fed C diet (1.8% n-3 HUFA in diet) was extended to spawning quality such as percentages of fertilised and hatched eggs.     

Utilization of different raw and pre-gelatinized starch sources by juvenile yellowfin seabream Sparus latus

Raw corn starch (RCS), raw tapioca starch (RTS), raw potato starch (RPS), pre‐gelatinized corn starch (PCS), pre‐gelatinized tapioca starch (PTS) and pre‐gelatinized potato starch (PPS) were evaluated as starch sources in diets for yellowfin seabream Sparus latus in a 56‐day growth trial. Seven isonitrogenous semi‐purified diets comprising a non‐starch cellulose control diet and the six different starch sources holding 200 g kg⁻¹ starch each were prepared and fed to triplicate groups of juvenile yellowfin seabream S. latus. Fish were fed for 8 weeks. Weight gain (WG) and specific growth rate (SGR) for fish fed RCS, RTS and RPS diets were equal, as well as for fish fed PCS, PTS and PPS diets, but values in groups fed the raw starch sources were significantly higher compared with fish fed the pre‐gelatinized starches. Feed efficiency and protein efficiency ratio in fish fed different starch source diets showed no significant differences but were significantly higher than those fed a non‐starch control diet. Protein productive value was improved by starch incorporation to diets. PCS, PTS or PPS groups showed lower feed intake compared with RCS, RTS or RPS groups, and the differences were significant between PCS, PPS and RCS, RPS groups. Whole‐body protein and ash contents and muscle compositions were not affected by different starch sources. Whole‐body and liver lipid contents, liver moisture and glycogen contents were significantly affected by starch source. Values of hepatosomatic index, intraperitoneal fat ratio, viscerosomatic index and condition factor did not vary between experimental treatments. Plasma total protein concentration for RCS, RTS or RPS fed fish was significantly higher than that for PCS, PTS or PPS fed fish, but significantly lower than that for non‐starch fed fish. Plasma cholesterol and triacylglycerol concentrations were unaffected by starch source, but were significantly higher in fish fed the non‐starch control diets. Plasma glucose concentrations in all dietary groups were relatively stable. In conclusion, raw corn, tapioca and potato starches at a 200 g kg⁻¹ inclusion level were well utilized as energy sources by yellowfin seabream, which was evidenced by better WG and SGR. Pre‐gelatinization of the starches had no positive effect on starch utilization.     

Effects of different dietary lipid sources on growth performance,antioxidant enzyme activities and biochemical composition of juvenile swimming crab,Portunus trituberculatus

An 8‐week feeding trial was conducted to evaluate the effects of dietary lipid sources on growth performance, antioxidant enzyme activities and biochemical composition of juvenile swimming crab Portunus trituberculatus of initial weight 2.34 ± 0.08 g. Four different diets were formulated to contain fish oil (FO), soybean oil (SO), linseed oil (LO) or palm oil (PO). The highest final body weight, weight gain, specific growth rate and molting frequency were observed in crabs fed the FO diet. Crabs fed the SO diet showed higher glutathione peroxidase, superoxide dismutase (SOD) and catalase (CAT) activities in both serum and hepatopancreas than those fed the FO diet. The lowest malondialdehyde concentration in hepatopancreas and serum were occurred at crabs fed the SO diet. Crabs fed the LO diet had significantly higher SOD and CAT activities in hepatopancreas compared with those fed the FO diet. Crabs fed the PO diet had the highest activities of fatty acid synthase and carnitine palmitoyltransferase 1 activities in hepatopancreas among all treatments. Fatty acid compositions both in hepatopancreas and muscle reflected those of diets. Overall, these findings demonstrated that physiological–biochemical characteristics and lipid metabolism were significantly regulated by different dietary lipid sources. Moreover, dietary SO and LO supplementation could improve antioxidant ability.     

Dietary administration of astaxanthin improves feed utilization,growth performance and survival of Asian seabass,Lates calcarifer (Bloch, 1790)

This study was undertaken to assess the impacts of dietary astaxanthin supplementation on growth performance, feed utilization, survival, and serum growth hormone (GH) availability of Asian seabass, Lates calcarifer, with special reference to dose–response relationships and variations during different feeding phases (short‐term, medium‐term and long‐term). Fish were fed the following diets in triplicate for 90 days: the control (CD), AX50 (50 mg astaxanthin/kg diet), AX100 (100 mg astaxanthin/kg diet) and AX150 (150 mg astaxanthin/kg diet). The findings revealed that fish exhibited significant linear increments (p < .05) in specific growth rate (SGR), weight gain, feed utilization efficiency and survival when fed various diets with escalating levels of astaxanthin. Supplementation with dietary astaxanthin significantly augmented (p < .05) GH levels in fish. Significant positive associations (p < .05) were observed between circulating serum GH levels and SGR of fish from all groups following three consecutive feeding phases, denoting a robust cause‐and‐effect relationship. Circulating GH concentrations were considered as a sensitive biomarker of growth performance in Asian seabass. This study illustrated that supplemental astaxanthin could be administered in culture protocols to improve the growth rate and commercial hatchery production of Asian seabass, and possibly other teleost species.     

Growth performance and body composition of white seabream (Diplodus sargus) juveniles fed diets with different protein and lipid levels

An 83‐day feeding trial was carried out to determine the effect of different dietary protein and lipid levels on the growth performances and carcass composition of white seabream. Juveniles (10.7±0.2 g) were fed to satiation on four diets, varying in protein (15% and 28%) and lipid (12% and 16%) levels. The best growth performance was observed in fish fed on diets with higher protein level. Dietary lipids did not affect growth performance. Voluntary feed intake decreased with a increasing dietary protein level at both dietary lipid levels. Feed conversion ratio improved with the increase in dietary protein and lipid levels. Carcass composition remained unaltered by dietary protein levels (P>0.05). Carcass protein content tended to decrease, while lipid content tended to increase in groups fed on 16% lipid, compared with the 12% lipid groups. Additionally, protein retention was higher in fish fed on low‐protein and low‐lipid levels, compared with the high‐protein and high‐lipid group (29% vs. 19%). Lipid retention increased significantly with dietary protein level (P<0.001). Energy retention improved with dietary protein, but was not affected by dietary lipid levels. On the basis of our results, feeding white seabream on 15% dietary protein had a negative effect on growth and feed utilization. Dietary lipid did not induce a protein‐sparing action in Diplodus sargus juveniles.     

不同脂肪源对黄颡鱼幼鱼生长性能、体成分、血清生化指标、体组织脂肪酸组成及抗氧化能力的影响

为研究不同脂肪源对黄颡鱼幼鱼生长性能、体成分、血清生化指标、体组织脂肪酸组成及抗氧化能力的影响,进行为期8周的养殖实验。实验配制了4种分别添加有椰子油(CO)、苏子油(PO)、葵花籽油(SO)、鱼油与葵花籽油1∶1混合油(FO/SO)的等氮等脂的饲料,喂养平均初始体质量为(1.52±0.00)g的黄颡鱼幼鱼。实验结果显示:不同脂肪源对黄颡鱼终末体质量(FBW)、增重率(WGR)、特定生长率(SGR)和成活率(SR)均无显著影响,对饲料系数(FCR)影响显著,各组SR均在95%以上。各组间的肝体比(HSI)、肥满度(CF)均有显著性差异,而脏体比(VSI)和肠脂比(IPR)无显著性差异。HSI和CF均以鱼油与葵花籽油1∶1混合油(FO/SO)组最高,葵花籽油(SO)组最低。黄颡鱼的鱼体水分、粗蛋白和灰分不受饲料脂肪源的影响,而椰子油(CO)组的粗脂肪含量显著高于其他3组,为10.51%,剩余3组间无显著性差异。饲料中脂肪源对黄颡鱼肌肉、肝脏组织脂肪酸组成和含量影响显著,并且肌肉和肝脏中脂肪酸含量变化与饲料中相应脂肪酸含量变化基本一致,椰子油(CO)组组织中饱和脂肪酸(SFA)含量最高,苏子油(PO)组组织中亚麻酸(ALA)和n-3 PUFA含量最高,葵花籽油(SO)组组织中亚油酸(LA)和n-6 PUFA含量最高,而鱼油与葵花籽油1∶1混合油(FO/SO)组组织中脂肪酸较为均衡。黄颡鱼血清中的总蛋白(TP)、白蛋白(ALB)、球蛋白(GLOB)、白蛋白/球蛋白(A/G)、谷草转氨酶(AST)、总胆固醇(CHOL)、甘油三酯(TG)、血糖(GLU)、肌酸激酶(CK)含量不受饲料脂肪源的影响。各组黄颡鱼肝脏中超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽S转移酶(GST)活性有显著差异。椰子油(CO)组的SOD和GST活性最高,而MDA含量最低。研究表明,在添加豆油的基础上,椰子油、苏子油、葵花籽油和鱼油与葵花籽油1∶1混合油都可以用作黄颡鱼饲料的脂肪源;证实了鱼体组织中脂肪酸组成基本可以反映饲料脂肪酸组成,并且说明了黄颡鱼具有延长和去饱和ALA和LA的能力。     

Effects of the dietary protein : lipid ratio on growth and nutrient utilization in gilthead seabream (Sparus aurata L.)

Gilthead seabream Sparus aurata L. (initial mean body weight: 42.5 g) were fed four experimental diets containing either 47 or 51% of dry matter (DM) as protein and either 15 or 21% as lipid for 12 weeks. Each diet was hand-distributed to triplicate groups of 60 fish, three times a day until satiation. The digestibility coefficients of the dietary components were determined using chromic oxide as a marker. The levels of protein or lipid in the diets did not affect the digestibility. Fish regulated their feed intake and attained the same weight at the end of the experiment. However, feed efficiency varied between diets, with best values obtained with both diets containing 21% lipid. When diets contained only 15% lipid, feed efficiency increased with dietary protein level. Nitrogen retention was significantly higher with high fat diets regardless of dietary protein level. Neutral lipid deposition was significantly higher in liver for diets rich in lipids. It was elevated in muscle only in fish fed the diet containing 47% protein and 21% lipid and this deposition in muscle contributed to a significant increase in body fat content. Phosphorus load to the environment, measured as percentage retention of ingested or digestible phosphorus, was significantly lower with both diets higher in lipids.